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itteilungen des
ärntner otanikzentrums
lagenfurt
ulfenia 25 –
Floral morphology and micromorphology of selected Maxillaria species
(Maxillariinae, Orchidaceae)
onika ipińska gnieszka owalkowska
Summary: he genus Maxillaria s l constitutes the core of the subtribe axillariinae enth t is
estimated that ca of the Maxillaria species attract pollinators by empty promises mong the
rest there are three types of reward nectar pseudopollen and waxlike substances n this paper we
present the results of the investigation of lip epidermis of species from sections and one complex
or the study we used scanning electron microscope n all studied species the presence of the
papillae in various shapes has been demonstrated bpyriform papillae seem to be the most common
and their presence has been noticed on the labellar surface of species from all investigated sections
onical papillae have been found on the lip surface of species from sections villiform – in
species from sections clavate papillae – only in species each from dierent sections and elliptic
papillae have been noticed only in a single species richomes are limited to species seudopollen
has been recorded only in species from the Grandioracomplex esidues of some kind of secretion
were observed on the lip surface of species from dierent sections n species papillae occurred
also on the outer surface of the lip
Keywords: morphology micromorphology Maxillaria axillariinae rchidaceae
he genus Maxillaria uiz av constitutes the core of the subtribe axillariinae enth
and the tribe axillarieae tzer rchidaceae uss ts representatives, in the broad sense
are distributed from outh lorida through entral merica and the aribbean slands to
outh merica southern to northern rgentina he genus was rst described by ipólito uiz
ópez and osé ntonio avón iménez in in Flora Peruviana et Chilensis Prodromus he
publication included a brief description of the genus and an illustration with various views of
the ower and its parts nfortunately the authors did not indicate which of the sixteen species
mentioned in the text is illustrated his oversight resulted in the later taxonomic problems of
the entire subtribe axillariinae
nvestigations conducted since the middle of the th century revealed a great diversity of labellar
epidermises in many groups of orchids uch characters as papillae and trichomes could potentially
be used to serve as taxonomic characters he importance of foliar micromorphology is well known
and has already been utilized in the taxonomy of rchidaceae uss cited in
n contrast studies on labellar epidermis are still quite neglected there is only one
study presented by he main aim of this paper was the investigation
of the micromorphology of labellar epidermis in selected species of the genus Maxillaria s l
Classification
eneric classication of the subtribe axillariinae has been a challenge for the taxonomists
since its formal description by uiz and avón et al or a long time it has
been suspected that it is an assemblage of taxa consisting of morphologically disparate groups of
species et al stablishing the exact number of species belonging to the various
orphology and micromorphology of Maxillaria
genera or even the subtribe itself is extremely dicult since it depends mainly on the adopted
classication system and the concept of a genus t is said that Maxillaria s l covers about ⁄ of the
species belonging to the subtribe ccording to various researchers it contains
to species ver the last years Maxillaria has
been expanded and contracted based on morphological features to embrace or reject a number
of taxa eg
et al et al et al et al ore recently
phylogenetic analyses based on molecular techniques have redened this subtribe and realigned
the species genera and sections which it contains avies pers comm
n the latest classication suggested another way of classifying
Maxillaria s l hey concluded that narrowly dened genera are often dicult to diagnose
especially when the material is designated only to the genus level hey have decided to merge
all the presently recognized taxa under a megagenus Maxillaria
Morphology
epresentatives of Maxillaria s l vary widely both vegetatively and orally and are characterized
by the wide range of combinations of both set of features lants are usually epiphytic sometimes
lithophytic or terrestrial hey are always herbaceous with monopodial sympodial or dimorphic
growth forms abit may be caespitose or rhizomatous erect or less frequently pendent ome
species are caespitose at the juvenile stage becoming rhizomatous with age oots are glabrous
velamentous and usually branching he stem is rhizomatous mainly branching or erect cane
like and lacking pseudobulbs hen present pseudobulbs are usually ovoid to cylindrical laterally
compressed unifoliate often clustered along the rhizome and subtended by several imbricating
sheaths either foliaceous or not eaves are variable in form conduplicate to semiterete articulate
with the sheaths or with the apex of the pseudobulb hey can be sessile to petiolate oblong
oblongelliptic or often linear subterete elliptic or obovoid acute to obtuse symmetrical to
unequally bilobed at the apex he abscission layer of the apical leaf often projects above the
pseudobulb in a persistent stalk phyllopodium norescences are always singleowered
arising from the base of the pseudobulb or laterally from the nonpseudobulbous stem singly
or fasciculate he peduncle is usually enclosed in equidistant bractlike scales loral bracts
are either similar in size and shape to the peduncle scales larger or much smaller he owers
are minute to large with sepals and petals being free to the base glabrous often ringent he
vascular bundles of the tepals are often elastic brous and very strong he lip is usually much
shorter than the tepals often hinged with the columnfoot or sometimes rigidly attached to it
entire or lobed glabrous or pubescent he gynostemium is stout usually with or occasionally
without a prominent foot our pollinia are superposed in two pairs those of a pair are equal
or unequal attached via sticky caudicles to a distinct often more or less lunate viscidium he
fruit is subglobose to ellipsoid dehiscing laterally or apically
Reproductive biology of Maxillaria s. l.
he main pollinators of Maxillaria are stingless bees eliponini
part from them visits of bees from the subtribe uglossini ants from the
subfamily onerinae and hummingbirds have also been observed ccording to
Maxillaria etcheriana olfe is pollinated by the bumblebee
Bombus volucelloides Maxillaria rufescens indl M. grandiora unth indl and M. sanderiana
chb f ex ander by Eulaema cingulata and Maxillaria reichenheimiana ndres chb f by
Trigona testacea and T. amalthea.
t is estimated that as much as of the Maxillaria species attract pollinators with empty
promises which are the combination of visual tactile and olfactory stimuli et al
mong the species which oer some kind of reward there are three types nectar pseudopollen
farina and waxlike substances et al a t is believed that orchids which secrete
nectar can even double their chances of pollination and thus the formation of the fruits and
seeds ts production however is costly in terms of expended energy and used materials ntil
recently it has been believed that none of the species included in Maxillaria s l produces nectar
otwithstanding it has been found in several taxa eg Ornithidium coccineum acq alisb ex
r and Maxillaria anceps mes chweinf et al estimate that within the
genus only of the species produce nectar
n the lip surface of some Maxillaria species there is a whitish mealy coating called pseudopollen
as it resembles real pollen t is produced by fragmentation of the trichomes ccording to many
researchers it is produced in species which do not produce nectar or any other reward arina is
common in the representatives of the M. grandiora M. splendens and M. discolor alliances t is
believed that bees collect it from owers because of the nutrients it contains et al
hese include starch oils and proteins ccording to
et al of the taxa studied by them produce pseudopollen and have trichomes
with a slightly dierent construction but similar function
ewards in form of wax and resinous substances rich in lipids and aromatic amino acids occur
in about of species et al he secretions are produced by oral papillae
and trichomes on the surface of the lip suggested that these
substances are collected by bees as material for nest building t is probably the correct assumption
but it seems that this may be not the only reason for the insects acquiring waxy substances s
noticed by et al a due to the nutritional value waxes and resins can also be a
source of food substances hey were found on lip surface of Maxillaria cerifera arb odr
Maxillaria divaricata arb odr ogn and Maxillaria avoviridis arb odr ccording to
various authors the latter two taxa are synonymous with M. cerifera dditional function of
waxy substances is predicted in Maxillaria acuminata alliance hese secretions result in a glossy
surface of the lip which probably is involved in the process of attracting pollinators just like the
speculum in species of the genus Ophrys et al a
o far there are no records of pseudocopulation for the genus Maxillaria in its narrow sense
described it for Trigonidium obtusum indl which is classied on molecular
basis by some researchers as representative of Maxillaria s l echanism of pseudocopulation in
this particular case is quite unique as the deposit of pollinia does not occur as a result of insect
mating attempts with one of the elements of the ower but when it tries to get out of the trap
ower he only observed pollinators visiting the owers of T. obtusum were male bees of Plebeia
droryana eliponini t seems that a key stimulus in this case is the smell uring very warm
days the owers of this species emit a sweet scent to some extent reminiscent of the aroma of
lemons ince the surface of the sepals and petals is covered by a substance similar
to wax landing insects glide and become trapped inside the ower hey spend from to
orphology and micromorphology of Maxillaria
seconds in the perianth o be released they must enter the space between the
gynostemium and lip and receive pollinia resultantly ollination occurs when insect falls into
the trap ower bearing pollinia brought from another ower he fact that ying drones try to
copulate with males that had landed earlier on the tepals led to prejudge that this
case is actual pseudocopulation
lowers of species that are pollinated by birds tend to be coloured from red to pink from orange
up to yellow or white rarely reddishpurple or blue hey produce abundant nectar but do not
emit odour or create nectar pathways o far there is no conclusive evidence for ornithophily in
Maxillaria ll reports on this topic are based on a single observation made by
who observed the hummingbird Panterpe insignis visiting an unidentied species
of Maxillaria with pink tubular owers ccording to et al owers
of Maxillaria coccinea and M. sophronitis in terms of morphology meet a range of criteria
characteristic of the hummingbirdpollinated owers pollinated by birds but dier from those
in the presence of sweet honey scent
Materials and methods
ips from owers of species classied in Maxillaria s l were studied he owers were preserved
in ew ethanol formaldehyde glycerol water or openhagen mixtures
ethanol glycerine water and were obtained from otanical ardens eidelberg
annover arburg and ienna and were deposited at the epartment of lant axonomy and
ature onservation of the niversity of dańsk he list of vouchers is presented in able
loral material preserved in ew or openhagen mixtures was dehydrated using an ethanol series
ollowing criticalpoint drying in a ritical oint ryer mitech apparatus specimens
were mounted onto stubs he stubs were coated with gold using a putter oater pi
odule he samples were examined and photographed using a hilips canning lectron
icroscope
n the study the terminology of surface characters was used in accordance with previously
published literature eg et al
he scientic names follow the classication of
Results
Maxillaria section Aggregatae Pfitzer
Maxillaria callichroma chb f onplandia
Maxillaria callichroma ig has a lobed lip elliptic in general outline up to cm long and
cm wide he lateral lobes are erectincurved obliquely ovate obtuserounded he middle
lobe is elliptic obtuse and distinctly keeled below t is up to cm long he callus extends from
the lip base to the middle lobe and is broadly obtuserounded in front pubescent throughout
he base of the adaxial lip surface as well as the callus is composed of multicellular trichomes
being in dierent developmental stages ig – from clavate papillae to single or clustered
liform and clavate trichomes apillae are observed also between the trichomes ig he
dierence concerns the coverage density and the length of the trichomes he highest density and
length are at the middle lobe base whereas at the top of the callus only few unicellular trichomes
have been noticed ig he surface of the callus is built by polygonal convex cells covered
by the lm of secretory material ig he median part of the lip consists of clavate and
obpyriform papillae ig – he proximal part is rugose ig covered by obpyriform
papillae heir accumulation is found near the base of the lip as well as near the apex of the middle
lobe where the shape of these is usually rounded he surface in some places seems to be folded
what can be due to aggregations of idioblasts with raphides in the subepidermis and in the whole
tissue ig he abaxial outer surface of the lip is also covered by few trichomes ig
Maxillaria luteoalba indl rchid inden
Maxillaria luteoalba ig has a lobed lip elliptic in general outline t is about – cm
long and – cm wide he sidelobes are erectincurved rectangular and obtuse he middle
lobe is transverse broadly ovate and obtuse he callus is oblong obtuse extending from the base
of the lip to about ⅓ of its length and abruptly elevates at the apex he median part of the lip
base is densely covered adaxially with trichomes ig t the base dierent developmental
stages of the trichomes occur from obpyriform papillae elongated twocelled trichomes to long
multicellular uniseriate and sometimes dichotomously divided ig he sidelobes are
glabrous in general view but their margins on the inner adaxial surface ig are densely
covered with obpyriform papillae and single twocelled trichomes ig
Table 1.he vouchers list of the materials used for the research
ection pecies ccession umber in spirit collection
Aggregatae tzer Maxillaria callichroma p
Maxillaria luteoalba p
Arachnites hristenson Maxillaria reichenheimiana p
Cucullatae hristenson Maxillaria cucullata p
Maxillaria praestans p
Ebulbes tzer Maxillaria graminifolia p
Maxillaria ramosa p
Erectae tzer Maxillaria ponerantha p
Maxillaria tenuifolia* p
Multiorae hristenson Maxillaria ochroleuca p
Ornithidium alisb hristenson Maxillaria aurea p p
Maxillaria purpureolabia p
Repentes tzer
Maxillaria marginata p
Maxillaria picta p
Maxillaria cf mosenii* p
Rufescens hristenson Maxillaria rufescens p
Urceolatae hristenson Maxillaria vitelliniora p
Trigonae hristenson Maxillaria pterocarpa* p
randiora omplex Maxillaria molitor* p
Maxillaria striata* p
orphology and micromorphology of Maxillaria
Maxillaria section Arachnites Christenson
Maxillaria reichenheimiana ndrés chb f ard hron gric azette
he lip of Maxillaria reichenheimiana ig is lobed elliptic sparsely pubescent and about
– cm long and – cm wide he lateral lobes are erect and obliquely oblong he middle
lobe is broadly ovate with a thinner margin obtuse he callus ig is linearoblong and
extends from the base of the lip to above the middle he lip apex is rugose built by obpyriform
papillae ig – ome trichomes are scattered on the lip and callus ig – hey consist
Figure 1. Maxillaria callichroma chb f verview of the owers hoto credit arkus ngler – multicellular
trichomes – top of the callus with few unicellular trichomes – closeup on the callus edge with unicellular
trichomes – surface of the callus built by polygonal convex cells covered by a lm of secretory material –median
part of the lip consists of clavate and obpyriform papillae – surface in some places seems to be folded what can
be due to aggregations of idioblasts with raphides in the subepidermis and in the whole tissue – proximal part
rugose covered by obpyriform papillae – abaxial outer surface of lip covered by few trichomes cale bars = m
– m
Figure 2. Maxillaria luteoalba indl – and Maxillaria reichenheimiana ndrés chb f – – overview
of the ower hoto credit ohn arigos – general view of the lip base densely covered adaxially with trichomes
– dierent stages of trichome development from obpyriform papillae elongated twocelled trichomes to long
multicellular uniseriate trichomes – elongated twocelled and long multicellular uniseriate trichomes sometimes
dichotomously divided – overview of the lateral lobe surface – closeup of the lateral lobe surface obpyriform
papillae and single twocelled trichomes – overview of the ower hoto credit aniel claren – closeup of
the midlobe surface with callus scattered trichomes – rugose lip apex built by obpyriform papillae – lip surface
rugose built by obpyriform papillae – closeup of the or morecelled trichomes scattered on the lip and callus
cale bars = mm mm m m
orphology and micromorphology of Maxillaria
of or more cells ig previously observed bicellular trichomes
on the lip and stated that they morphologically resemble the food hairs of Polystachya ook
described by et al
robable pollinators of this species are Trigona testacea and T. amalthea
Maxillaria section Cucullatae Christenson
Maxillaria cucullata indl dwardss ot eg t
he lip of Maxillaria cucullata ig is lobed and from up to cm long he side
lobes are erectincurved obliquely elliptic obtuserounded and about ⅓ of the lip length he
middle lobe is elliptic obtuserounded he callus is conspicuous broadly oblong and slightly
shaped in transverse section he lip surface is glabrous papillose only at the callus surface he
conical papillae are in dierent stages of development ig ccording to
M. cucullata indl M. hematoglossa ich aleottii and M. lexarzana oto renas
hiang all representatives of the Maxillaria cucullata alliance have glabrous labella completely
devoid of papillae hey pointed out that in M. meleagris indl which is thought to be closely
related to the members of discussed alliance the labellum is papillose covered with conical
papillae with pointed tips ince M. cucullata is thought to be a quite variable species this may
cause problems with a correct taxonomic identication ndeed there was a time when nearly all
of the species in the section had been included in the highly variable M. cucullata
t can be however easily distinguished from similar species by almost wholly unmarked
sepals and petals ig and this ts the description of the ower used in this research
Maxillaria praestans chb f ard hron ns
he lip of Maxillaria praestans ig is lobed and somewhat curved t is about cm long
he middle lobe is big rounded in general outline he lateral lobes are upcurved he callus is
thick and eshy with raised sides from the base and a smooth surface ig he lip surface
of M. praestans is papillose foldedrugose near the apex ig sometimes with celled
trichomes he folds consist of cuboidal cells ig he lip base is densely covered with
obpyriform to villiform papillae ig
Maxillaria section Ebulbes Pfitzer
Maxillaria graminifolia unth chb f nn ot yst
he lip of Maxillaria graminifolia ig is unlobed and lightly constricted at the middle to
obscurely lobed with the blade narrower above the central constriction n general outline it
is broadly obtuse roundedsubtruncate sometimes slightly notched at the apex and retuse t is
about – cm long and – cm wide he callus is eshy glossy with knoblike apex
he lip surface is papillose densely covered with papillae on both adaxial inner and abaxial
outer surfaces ig he shape of the papillae varies from obpyriform conical to villiform
ig ear the median part trichomelike papillae are observed he surface of the callus
is rather glabrous but some multicellular moniliform trichomes are present ig hey
consist of at least cells whereas the apical cell seems to be the secretory one ased only on
their morphology they could potentially play a similar role as food hairs esidues of some kind
of secretion are observed on both papillae and trichomes ig
Figure 3. Maxillaria cucullata indl – and Maxillaria praestans chb f – – overview of the owers
hoto credit ohn arigos – conical papillae in dierent stages of development – overview of the ower of
Maxillaria a praestans hoto credit oss ayton – view of the lip apex and callus – lip surface papillose
foldedrugose near the apex – folds consisting of cuboidal cells – lip base densely covered with obpyriform to
villiform papillae – closeup of the lip base densely covered with obpyriform to villiform papillae cale bars = mm
m , G m m
orphology and micromorphology of Maxillaria
Figure 4. Maxillaria graminifolia unth chb f – and Maxillaria ramosa uiz av – – overview of the
owers hoto credit ric unt – papillose lip surface covered with papillae on both adaxial inner and abaxial
outer surfaces – various shapes of the papillae obpyriform conical and villiform – surface of the callus rather
glabrous with some multicellular moniliform trichomes – papillae covered with residues of secretion of some
kind – overview of the ower of Maxillaria a ramosa hoto credit ric unt – view of the lip – view of
the lip apex and gynostemium – closeup of the lip surface somewhat folded built by obpyriform papillae cale
bars = mm m m m
Maxillaria ramosa uiz av yst eget l eruv hil
he lip of Maxillaria ramosa ig is lobed elliptic in general outline t is up to cm long
and cm wide he lateral lobes are erect obliquely obovate and obtuserounded he middle
lobe is oblongrectangular obtusesubtruncate he callus ig – is oblong and extends
from the base of the lip to the base of the middle lobe he lip surface is slightly papillose t is
glabrous rugose and built by obpyriform papillae in its proximal and median parts ig –
o presence of any secretory material has been noticed
Maxillaria section Erectae Pfitzer
Maxillaria ponerantha chb f onplandia
he lip of Maxillaria ponerantha ig is unlobed to obscurely lobulate by the suberect
incurved lateral margins and light constriction above the middle of the blade t is obovate in
general outline obtuse and very shallowly notched at the apex he callus is low oblanceolate
Figure 5. Maxillaria ponerantha chb f – overview of the ower of Maxillaria a ponerantha hoto credit ohn
arigos – view of the lip and callus – front view of the glabrous callus and median lip part – minutely
papillose margins – closeup of the lip apex with villiform conical and sometimes obpyriform papillae at the margins
oldedrugose surface some of the papillae occur in aggregations of more than cells forming threedimensional
starlike clusters – outer surface of the lip is covered by conical papillae cale bars = mm mm m
m
orphology and micromorphology of Maxillaria
and extends from the base of the lip ig to its middle part he callus and median lip part
are glabrous ig t is cm long and cm wide he margins are minutely papillose
ig – he shapes of the papillae at the margins are villiform and conical sometimes
obpyriform ig he surface in this region is foldedrugose and some of the papillae occur
in aggregations of more than cells forming threedimensional starlike clusters ig he
outer surface of the lip is covered by conical papillae ig iterature data support at least
partly the results presented above and according to the lip is clothed
by conical and villiform papillae
Maxillaria tenuifolia indl dwardss ot eg sub t
pecies unplaced in any section proposed by hristenson but it seems that it belongs to Maxillaria
section Erectae tzer
he lip of Maxillaria tenuifolia ig is unlobed to obscurely pandurate by way of a slight
constriction above the middle t is elliptic obtuse – cm long and – cm wide he
callus is broadly oblong and extends from the base of the lip ig to about ⅓ of its length
he lip surface including callus ig is densely papillose ig – covered by villiform
papillae he one occurring near the lip center seem to be longer than the one near the sides he
presence of some remnants of secretion has been noticed ig – ccording to
the lip of Maxillaria tenuifolia is heterogeneous his means that the epidermis
is composed by more than one type of cells reported that conical
papillae occur on the column and anther cap and the lip surface is covered with villiform papillae
what supports the results presented above s pointed out the
structure of the labellar epidermis is constant regardless of whether the typical red form or yellow
one is examined
Maxillaria section Multiflorae Christenson
Maxillaria ochroleuca odd ex indl en p rchid l
he lip of Maxillaria ochroleuca ig is thick and eshy narrowly rhomboidovate slightly
pubescent above with subcordate base ear the middle it is deeply lobed ateral lobes are
large oblong with rounded apices heir margins are at nonundulate he terminal lobe is
thick broadly ligulate with rounded apices ts margins are undulate and thinly crenulate he
callus is thick ligulate ig with shortened apex t extends from the base to the middle
part of the lip hort multicellular and uniseriate trichomes are scattered on the lip ig –
hey consist of to cells he lip surface of M. ochroleuca is papillose densely covered with
obpyriform and clavate papillae ig – n some places the surface is somewhat folded
rugose ig and observed on the
lip the presence of obpyriform papillae and simple uniseriate trichomes consisting of – cells
ccording to et al b it is speculated solely on morphological grounds
that these hairs may become detached or fragmented to form pseudopollen ndeed inger has
observed workers of Trigona bees collecting these hairs from the tip of the labellum inger
pers comm in e had also reported that they were chewed and stored
in a pastelike form on the corbiculae urthermore inger stated that the bees actually collected
papillae rather than hairs as the labellar papillae of the closely related M. buchtienii chltr are
known to contain starch
Figure 6. Maxillaria tenuifolia indl – and Maxillaria ochroleuca odd ex indl – – overview of the
owers – overview of the lip apex – closeup of the lip and callus surface covered by villiform papillae –
some remnants of secretion visible on papillae – overview of the ower hoto credit uiz ilipe arella – view
of the lip base and callus with scattered short multicellular and uniseriate trichomes – closeup of papillose lip
densely covered with obpyriform and clavate papillae in some places somewhat foldedrugose – closeup of the
trichomes cale bars = mm mm m m
orphology and micromorphology of Maxillaria
Maxillaria section Ornithidium (Salisb.) Christenson
Maxillaria aurea oepp ndl illiams aldasia
he lip of Maxillaria aurea ig is rigid eshy with the margins of the upper part incurved
and wavy giving the appearance of being lobed t is – cm long and – cm wide when
Figure 7. Maxillaria aurea oepp ndl illiams – and Maxillaria purpureolabia ennett
hristenson – – overview of the owers hoto credit urt uzard – general view of the lip apex –
papillose lip surface obpyriform mainly in proximal part to conical and villiform papillae – obpyriform papillae
on the lip surface – overview of the ower – overview of the lip – slightly papillose lip surface – lip apex
covered with obpyriform and conical papillae cale bars = mm mm m m
extended he median smooth callus expands on the basal half of the lip length and is oblong
ligulate in general outline ig he labellum surface is papillose ig – bpyriform
mainly in proximal part to conical and villiform on margins in lateral parts papillae have been
observed hey are found at both lateral and middle lobes of the lip apillae are obpyriform in
general outline ig – o presence of wax or other secretion could be found
Maxillaria purpureolabia enn hristenson c rchid eruv pl
he lip of Maxillaria purpureolabia ig is obscurely lobed elliptic in general outline and
it is about cm long and cm wide he lateral lobes are erect obliquely oblanceolate and
obtuse he middle lobe is broadly ovate and obtuse he callus ig is oblongellipsoid
obtusetruncate and extends from the base of the lip to about its middle he lip surface is slightly
papillose ig – he lip apex is covered with obpyriform and conical papillae ig
he papillae seem to occur on both top and bottom side of the lip
Maxillaria section Repentes Pfitzer
Maxillaria marginata enzl l erres ard urope –
Maxillaria marginata ig has a lobed lip elliptic in general outline and it is up to cm
long and cm wide he lateral lobes are obliquely obovate and obtuserounded he middle
lobe is oblongelliptic obtuserounded he callus ig is oblong obtuserounded and
extends from the base of the lip to its middle part below the base of the middle lobe he
lip surface is papillose covered with obpyriform papillae and celled trichomes with clavate
terminal cells ig – esidues of some kind of secretion have been observed on the apex
of the lip ig orkers of Trigona sp pidae eliponini have been observed during
the pollination of the owers of this species
reported that there is no evidence for the presence of trichomes or any food rewards in
the owers of M. marginata what has been clearly undermined by our results
Maxillaria picta ook ot ag t
Maxillaria picta ig has a lobed lip broadly elliptic in general outline t is cm long
and cm wide he lateral lobes are erectincurved transversely elliptic and obtuserounded he
middle lobe is ellipticovate obtuserounded and slightly crenulated he lip surface including
the callus is papillose t is densely covered by clavate conical and villiform papillae ig –
he lower part of the callus is almost glabrous with villiform papillae occurring occasionally
ig ts middle part is densely covered by conical and clavate papillae with strongly rounded
tips scattered between them ome trichomes probably consisting of or more cells with globose
or elliptic top cells have been observed ig he owers of M. picta are strongly scented
emitting honeylike fragrance ccording to they do not produce
nectar or any other reward reported that its lip is lacking trichomes
but is heavily clothed with villiform papillae M. picta is pollinated by the stingless bee Trigona
spinipes t is suspected that the papillae produce an intoxicating
fragrance which facilitates pollination by partially anaesthetizing the insect
ccording to et al and et al it is composed mostly of
linalool phenylacetaldehyde and bocimene investigated the
anatomy of the resinsecreting and putative resinmimic species including M. picta heir research
revealed that the conical villiform or subclavate epidermal papillae located on the adaxial labellar
orphology and micromorphology of Maxillaria
Figure 8. Maxillaria marginata enzl – and Maxillaria picta ook – – overview of the ower –
overview of the medial part of the lip – obpyriform papillae and celled trichomes with clavate terminal cells
– closeup of the celled trichome with clavate terminal cell and residues of some kind of secretion – overview of
the ower of Maxillaria a picta – lip surface densely covered by clavate conical and villiform papillae – lower
part of the callus almost glabrous with villiform papillae occurring occasionally – trichomes consisting of at least
two cells with globose or elliptic top cell cale bars = mm – m m m
surface function as secretory tissue hat is more the presence of the labellar secretion has been
demonstrated based on combined light scanning and transmission electron microscopy and
histochemistry results t is thought to be the fragrance residues
Maxillaria cf mosenii raenzl onigl venska et cad ns t f
pecies unplaced in any of the sections proposed by hristenson but it seems that it belongs to
the section Repentes hristenson
he lip of Maxillaria mosenii ig is obovate to oblanceolate obscurely lobed and about
cm long and cm wide he middle lobe is orbicular with rounded apex which can be retuse
he callus is oblong – mm long and extends slightly above the ⅓ of the lip length he
adaxial inner surface of the lip base ig and callus ig of Maxillaria cf mosenii is
glabrous he surface towards the margins is rugose and at the margins densely covered with
conical papillae which are gathered in threedimensional clusters ig – resembling
somewhat a sea anemone s et al reported M. mosenii raenzl has conical
labellar papillae and no presence of trichomes has been demonstrated ccording to the authors
M. mosenii raenzl var hatschbachii chltr oehne possesses conical papillae on the column
anther cap as well as on the lip he papillae contain proteins but neither lipids nor starch
Maxillaria section Rufescens Christenson
Maxillaria rufescens indl dwardss ot eg sub t
he lip of Maxillaria rufescens ig is lobed ellipticovate in general outline t is cm
long and cm wide he lateral lobes are erectincurved obliquely ovate acute and about
half of the lip length he middle lobe is rectangular roundedtruncate he callus ig is
oblong and extends from the base of the lip to below the base of the middle lobe he lip surface
is papillose covered with clavate papillae on the callus and near the central part of the middle
lobe ig and on the whole surface with obpyriform papillae ig – he remnants
of secreted material have been observed ig his observations are strongly supported by
already published data ccording to the shape of labellar papillae can
be clavate or obpyriform they contain protein lipids and starch he presence of the latter one
is common among other members of this alliance he labellar surface is generally clothed with
obpyriform papillae hose located towards the center of the lip are clavate and much larger by
distended apices hey stated that these papillae at the center of the lip
often contain more starch than the others t is thought that the papillae produce an intoxicating
fragrance which can partially anaesthetize the insect and thus facilitates pollination
reported the vanillin production in M. rufescens hey pointed also to
another theory even in species which at rst sight seem to be rewardless food substances may
be present but located within papillae and are only accessible to gnawing insects owever there
is no direct evidence for this his could be the case in M. rufescens where according to
the unicellular hairs have delicate walls and contain aleurone grains and oil droplets
ccording to no presence of trichomes has been observed n opposite
observation was made by esearchers observed clusters of tightly
packed short to long unicellular claviform yellowish trichomes on the lip surface mainly in
the middle lobe region esearch conducted by et al supported this observation
and revealed that M. rufescens produce some reward trichomes for its pollinators
orphology and micromorphology of Maxillaria
Figure 9. Maxillaria rufescens indl – and Maxillaria mosenii raenzl – – overview of the ower hoto
credit ddie halen – view of the lip base – papillose lip surface covered with clavate papillae on the callus and
near the central part of the middle lobe with visible remnants of secreted material – closeup of the callus visible
remnants of secreted material and clavate papillae – lip surface covered with obpyriform papillae – overview of
the ower hoto credit uis enato – glabrous adaxial inner surface of the lip base and callus – adaxial
inner surface of the lip apex and callus rugose towards the margins and at the margins densely covered with conical
papillae gathered in threedimensional clusters – closeup of conical papillae gathered in threedimensional clusters
cale bars = mm mm m m m
Maxillara section Urceolatae Christenson
Maxillaria vitelliniora arb odr en p rchid ov
he lip of Maxillaria vitelliniora ig is unlobed broadly oblong in general outline
arching with shallowly suberect lateral margins obtuse with minute apical notch t is cm
long and cm wide he callus is an indistinct central thickened pad ig he apex
of the lip is covered with obpyriform papillae ig he lip surface is partly papillose ts
margins are clothed with conical and villiform papillae ig he basal and median part
is completely devoid of them o presence of secretion or any other kind of reward has been
observed vailable literature data seem to support presented results ccording to
conical and obpyriform papillae occur on the column and anther cap and the
lip is covered with conical papillae s reported the owers of this
species are rewardless what is upheld by the results presented above
Maxillaria section Trigonae Christenson
Maxillaria pterocarpa arb odr en p rchid ov
pecies unplaced in any of the sections proposed by hristenson but it seems to belong to
Maxillaria section Trigonae hristenson
he lip of Maxillaria pterocarpa ig is obscurely lobed elliptic in general outline
up to cm long and cm wide with incurved sides he middle lobe is broadly ovate to
suborbicular acute minutely warty with the warts arranged in rows he callus is oblong
somewhat dilated towards the apex obtuserounded t extends from the base of the lip to beyond
its middle reaches about ⅔ of the lip length he lip surface is papillose near the apex and margins
ig – but the median part is glabrous he shape of papillae is villiform he ones near
the edge of the lip are sometimes fused together in pairs ig he remnants of secretion
are visible on the papillae ig
‘Grandiflora Complex’
Maxillaria molitor chb f ard hron ser
pecies unplaced in any of the sections proposed by but it seems that it
belongs to the ‘randiora omplex’
he lip of Maxillaria molitor ig is unlobed but appears to be lobed due to the folding
t is elliptic in general outline and up to cm long and cm wide he lateral margins are
suberect he middle lobe is elliptic obtuse concave with undulate margins he callus is
broadly oblong and extends from the base of the lip to its middle part oth lip surfaces are
papillose he abaxial outer surface is densely covered by elliptical and villiform papillae
sometimes dichotomously divided ig he adaxial inner surface at the base is formed
by parallel arranged conical papillae with striated cuticle ig – he callus is covered by
obpyriform to globose papillae ig bundant masses of pseudopollen have been observed
on the adaxial surface of both middle including callus and lateral lobes ig –
seudopollen grains are lemonshaped attached together in moniliform chains with distended
cuticle and remnants of secreted material ig n the transverse section large cells most
probably idioblasts were noticed under the single layer of epidermis ig ccording to
orphology and micromorphology of Maxillaria
on the lip surface of M. molitor obpyriform papillae and moniliform
trichomes are present urthermore they pointed that wherever pseudopollenforming trichomes
occur labellar papillae tend to be obpyriform he component cells of the pseudopollen are
Figure 10. Maxillaria vitelliniora arb odr – and Maxillaria pterocarpa arb odr – – overview of
the ower hoto credit uiz ilipe arella – view of the lip – view of the lip apex covered with obpyriform
papillae – lip margins clothed with conical and villiform papillae – overview of the ower hoto credit ohn
arigos – view of the lip – view of the lip apex with visible remnants of secretion on the papillae – villiform
papillae at the lip apex near the edge of the lip sometimes fused together in pairs cale bars = mm mm
m
lemonshaped and squat in appearance with distinct polar papillae seudopollen contains protein
and starch but no lipid et al
Maxillaria striata olfe rchid ev
pecies unplaced in any section proposed by according to him it belongs
to the ‘randiora omplex
he lip of Maxillaria striata ig is obscurely lobed elliptic acute to obtuse t is about
– cm long he lateral lobes are suberect he middle lobe has undulate margins he
callus is oblong and extends to ⅔ of the lip length he lip surface is papillose he base and
the sides of the lip are covered with conical and villiform papillae arranged in rows ig
he lip surface is covered by obpyriform ig and conical papillae ig owards
the median part grains of pseudopollen ig – occur more abundantly reaching a peak
in the middle part of the middle lobe t appears that pseudopollen is formed from obpyriform
papillae ndeed some researchers connect the presence of the latter one with the occurrence of
pseudopollen lmost all papillae and pseudopollen grains are covered with residues of secretion
of some kind ig – esults presented above are supported by already published literature
data reported that on the lip surface of Maxillaria striata villiform
papillae occur ccording to et al its pseudopollen contain protein but no
starch n their opinion based on light microscopy observations there is slight but unconvincing
evidence for the presence of lipids
Discussion
he results of labellar micromorphology studies of Maxillaria reichenheimiana, M. cucullata,
M. ponerantha, M. tenuifolia, M. ochroleuca, M. marginata M. picta M. rufescens M. mosenii,
M. vitelliniora, M. molitor and M. striata generally conrm those previously obtained by
and coworkers et al et al ab
or and coworkers
et al
Comparison within the sections
Section Aggregatae Pfitzer. p to date more representatives of section Aggregatae have been
examined Maxillaria robusta and M. parkeri according to oer no
reward to their pollinators Maxillaria cf setigera possesses conical papillae and simple –celled
trichomes at the column the same type of papillae occurs at the anther cap and obpyriform
papillae with moniliform –celled trichomes at the lip surface have been observed
ccording to the same authors both labellar papillae and trichomes contain
starch and protein but no lipids stated that Maxillaria triloris has
trichomes and papillae with pointed tips and they concentrate at the lip margins those structures
presented therein on the gures – strongly resemble the ones observed in M. callichroma
in our research ater examined another specimen of Maxillaria,
this time identied as cf triloris hey have observed obpyriform papillae on the lip surface and
simple –celled trichomes his resemblance between all three specimens of M. callichroma
M. triloris and M. cf triloris may lead to the conclusion that either both species are extremely
similar in respect of their micromorphology or some misidentication has been made what is
orphology and micromorphology of Maxillaria
Figure 11. Maxillaria molitor chb f – overview of the ower hoto credit ric unt – villiform papillae
sometimes dichotomous with pseudopollen grain – adaxial inner surface at the base is formed by parallel arranged
conical papillae – closeup of the adaxial inner surface at the base with parallel arranged conical papillae with
striated cuticle – masses of pseudopollen – lemonshaped pseudopollen grains attached together in moniliform
chains – lemonshaped pseudopollen grains with distended cuticle and remnants of secreted material –
pseudopollen grains cale bars = mm m m m
quite common in this group t seems that the presence of obpyriform papillae and trichomes is
conservative but not a unique character of this section
Section Arachnites Christenson. o far eight other species from relatively large section Arachnites
have been examined M. buchtienii possesses conical papillae at the column and anther cap and
obpyriform papillae as well as – celled trichomes on the lip surface
ccording to the same authors labellar papillae contain protein and starch but no lipids these
substances are absent in trichomes ccording to et al spherical or obpyriform
epidermal papillae are confined to the distal part of the labellum and the callus in this species
and the uniseriate trichomes found on the lateral parts of the labellum are composed of three
to four elongate cells only n M. fractiexa conical papillae have been observed at the column
and anther cap additionally villiform and – celled trichomes on the lip M. lepidota indl
possesses obpyriform papillae with glands and –celled trichomes on the lip surface similar
structures occur in M. cf arachnites he authors stated that in the rst
species labellar papillae as previously described by become modied
into unicellular spherical glands hey observed that those are more abundant on the ventral
Figure 12. Maxillaria striata olfe – overview of the ower – conical papillae arranged in rows – obpyriform
papillae arranged in rows – papillae covered with residues of some kind of secretion – masses of pseudopollen
visible residues of some kind of secretion – single grain of pseudopollen cale bars = m m
m m
orphology and micromorphology of Maxillaria
surface of the labellum than the dorsal ccording to them around the anther and stigmatic
surface papillae may become enlarged or swollen and appear to contain a thin layer of peripheral
cytoplasm and a large vacuole with watery cell sap that occupies most of the cell n many species
eg M. lindleyana chltr another member of the section many of these conical papillae are
replaced by villiform papillae some of which are curved like a scythe
n the later paper et al stateed that in M. lepidota pseudopollen is present on the
adaxial and abaxial surfaces of the lip and is formed by the fragmentation of uniseriate moniliform
trichomes the four to six component cells of these trichomes are interspersed amongst typical
labellar obpyriform papillae between which occur enlarged secretory unicellular obpyriform to
spherical glands M. lindleyana has conical papillae at the column and the anther cap additionally
obpyriform ones occur on the lip surface as well s mentioned before many of these conical
papillae are replaced by villiform papillae
report clusters of trichomes for this species but this may be as well misnaming of villiform
papillae found by lc M. longissima has obpyriform papillae and moniliform
trichomes at the lip surface they contain protein and lipids but no starch
he same authors stated that solely on morphological grounds these trichomes might be
pseudopollenforming labellar hairs et al ab with
the fusiform component cells Maxillaria pseudoreichenheimiana has conical and villiform papillae
at the column obpyriform and villiform ones at the anther cap and obpyriform ones on the lip
surface as well as bicellular trichomes orphologically these resemble
the food hairs described by et al for certain species of Polystachya apillae and
trichomes contain protein and the latter one probably also lipids
stated that M. bradei another member of the section possess trichomes t seems that the presence
of the trichomes and obpyriform papillae is quite constant in this section the same as in section
Aggregatae
Section Cucullatae Christenson. ntil now two more species of section Cucullatae have been
examined M. hematoglossa and M. lexarzana he rst one possesses conical papillae at the
column surface conical and obpyriform ones at the anther cap and its lip is completely devoid
of any papilla he same authors observed conical papillae only at
the anther cap of M. lexarzana pointed out that in M. meleagris
indl which is thought to be closely related to the members of discussed section the labellum
is papillose covered with the conical papillae with pointed tips e have obviously observed
conical papillae on the lip surface in our research which may lead to the conclusion that some
identication errors might have occurred ndeed members of this group are often misidentied
and this may cause problems with correct taxonomic identication n fact there was a time
when nearly all of the species in the section were included in the highly variable M. cucullata
owever M. cucullata can be easily distinguished from similar species
by almost wholly unmarked sepals and petals and this ts the description of the ower used in
our research hus to resolve this problem further investigations are needed n general and
according to glabrous labella completely devoid of papillae were
found in M. cucullata, M. hematoglossa and M. lexarzana n M. praestans a species included by
hristenson to discussed section we observed that the lip base is densely covered with obpyriform
to villiform papillae t is therefore possible that a glabrous lip surface is neither a conservative
feature nor characteristic of this section
Section Erectae Pfitzer. nly two other members of section Erectae have been investigated n
Maxillaria procurrens indl conical papillae have been observed on the lip surface
Maxillaria variabilis has villiform and conical papillae at the column and lip
surface and conical ones at the anther cap
et al onical papillae are most common thus they are not of taxonomic
importance t is worth to mention that species of the discussed section investigated by us have a
more diverse labellar epidermis because we observed for instance also villiform and obpyriform
papillae
Section Multiflorae Christenson. o far only two members of section Multiorae have been
examined M. chlorantha and M. splendens ccording to members
of the M. splendens alliance have labella with uniseriate relatively fewcelled hairs – as well
as obpyriform papillae and it has been speculated that these hairs may become detached or
fragment to form pseudopollen et al ab istochemical analysis however
failed to demonstrate the presence of protein starch or lipids within such hairs in M. buchtienii
evertheless identical hairs occur in M. ochroleuca et al he presence of
obpyriform papillae and multicellular trichomes seem to be a constant feature for the members
of this section since they have been observed also in M. ochroleuca
Section Ornithidium (Salisb.) Christenson. nly one other species of section Ornithidium has
been examined to date n M. coccinea conical papillae have been observed at the anther cap and
lip surface although even papillose labella may have some glabrous regions
urthermore nectar production has also been demonstrated for this species
et al
Section Repentes Pfitzer. ight other species of section Repentes have been examined ccording
to M. barbosae oefgr ex orto M. chrysantha arb odr
M. consanguinea lotzsch M. gracilis odd M. kautskyi abst M. phoenicanthera arb odr
M. porphyrostele chb f M. ubatubana oehne possess neither papillae nor trichomes
reported that in M. chrysantha conical papillae occur at the column and anther
cap he same authors stated that the labellar epidermis of M. chrysantha produces wax upon its
surface and this protects the plant from desiccation ccording to et al owers of
both M. picta and M. porphyrostele are highly fragrant and the callus epidermis consists mainly
of cuboidal cells lthough and analyses of both species revealed small quantities
of epidermal secretion this unlike other secretions was barely visible using fluorescence
microscopy and may have represented fragrance residues ie that component of the fragrance
that remains after the more volatile constituents have vaporized especially as parenchyma cells
of M. porphyrostele contained droplets of presumed terpenoids as well as cuticular pores similar
to those found in osmophores of Restrepia unth and Scaphosepalum fitzer
were occasionally observed et al
have also examined a specimen identied as M. cf gracilis hey observed conical papillae at
the column anther cap and lip t the latter one occurred also obpyriform papillae and simple
– celled trichomes n the specimen of M. marginata used in our research the lip surface was
papillose covered with obpyriform papillae and celled trichomes with clavate terminal cells e
have also observed residues of some kind of secretion on the apex of the lip
reported that there is no evidence for the presence of trichomes or any food rewards in
the owers of M. marginata what clearly has been undermined by our results his may indicate
orphology and micromorphology of Maxillaria
that some identication error might have occurred reported that the
lip of M. picta is lacking trichomes but it is heavily clothed with villiform papillae
revealed that the conical villiform or subclavate epidermal papillae located
on the adaxial labellar surface function as secretory tissue s our research support the result
obtained by them in the case of papillae it does not support it in case of the trichomes since we
have observed some his may be caused either by the limited number of these as in the sample
examined by they might be skipped or by the incompatibility of
the naming used
n our research the adaxial inner surface of the lip base and callus of Maxillaria cf mosenii is
glabrous he surface towards the margins is rugose and at the margins densely covered with
conical papillae which are gathered in the threedimensional clusters resembling somewhat a
sea anemone s et al reported M. mosenii raenzl has conical labellar papillae
and no presence of trichomes has been found ccording to the authors M. mosenii raenzl
var hatschbachii chltr oehne possesses conical papillae at the column anther cap as well as
on the lip he papillae contain proteins but neither lipids nor starch
Section Rufescens Christenson. ntil now six other species of section Rufescens have been
examined herever pseudopollenforming trichomes occur labellar papillae tend to be
obpyriform owever this type of papilla may occur in the absence of
pseudopollen hairs as in M. rufescens indl M. acutifolia indl M. tenuibulba hristenson
and M. moralesii arnevali twood all members of discussed section
s reported the apices of these in particular the larger central
papillae are greatly distended and the papillae obtain a clavate prole except M. hedwigae
amer odson where the papillae tend to be somewhat fusiform or villiform oreover the
labella of M. acutifolia and M. tenuibulba produce a lipoidal secretion much like that found in
the M. acuminata alliance and some members of the M. discolor alliance et al ab
n M. acutifolia labellar papillae are conical or obpyriform with
secretory unicellular clavate papillae and hairs located centrally he latter are coated in secreted
material et al ccording to M. hedwigae amer
odson possesses fusiform and villiform papillae on the lip surface M. moralesii arnevali
twood conical obpyriform and clavate ones and M. tenuibulba hristenson obpyriform
ones at the column and anther cap and conical obpyriform and clavate papillae on the lip
et al also mentioned the presence of labellar hairs and a detached cuticle on the papillae
but cuticular pores were absent n M. chacoensis the epidermal papillae were clavate or villiform
and the surface secretion scant et al ccording to the same authors in M. richii
the adaxial secretory epidermis comprised unicellular secretory villiform or clavate papillae
or trichomes copiously coated more so than in M. acutifolia with secretion he presence of
obpyriform papillae seem to be constant but again it is not a unique feature of this section
Section Urceolatae Christenson. o date four other members have been of the section Urceolatae
ccording to M. acicularis erb ex indl and M. juergensii chltr
possess neither papillae nor trichomes n M. seidelii abst conical and obpyriform papillae
occur at the column conical obpyriform and villiform ones at the anther cap and conical ones
on the lip n M. vernicosa arb odr conical papillae occur at the
column anther cap and lip surface n M. vitelliniora the apex of
the lip is covered with obpyriform papillae he lip surface is partly papillose ts margins are
clothed with conical and villiform papillae vailable literature data seem to support the obtained
results ccording to conical and obpyriform papillae occur on the
column and anther cap and the lip is covered with conical papillae s
reported the owers of this species are rewardless what is upheld by the results presented
above onical papillae are most common he glabrous lip is not common but still not unique
to this section
‘Grandiflora Complex’. o far nine members of the informal complex ‘randiora’ have been
studied M. elegantula olfe possesses conical and villiform papillae at the column obpyriform
papillae and moniliform trichomes on the lip M. fucata chb f has
obpyriform papillae and moniliform trichomes on the lip surface which consist of fusiform
component cells n general the lip surface is largely papillose and
trichomes are scanty et al n M. huebschii the uniseriate moniliform trichomes
also occur mainly on the adaxial surface of the lip and are composed of up to seven spherical
component cells hose towards the base of the trichome however are elliptical or lemonshaped
et al n M. grandis pseudopollen is distributed predominantly on the adaxial
surface of the labellum but some pseudopollen is also present on the abaxial surface
et al ccording to et al it is formed by fragmentation of hairs arising
from the papillose epidermis ccording to the same authors both moniliform trichomes and
individual component cells or chains of cells are called pseudopollen when they become detached
from the labellum and form farina ach uniseriate pseudopollenforming moniliform trichome
usually consists of five to seven spherical component cells n M. roseola pseudopollenforming
moniliform trichomes arise as tufts from the adaxial papillose labellar epidermis which consists
of rounded to obpyriform papillae he basal cells of each trichome are elongate whereas those
towards the trichome apex are more or less spherical n M. irrorata chb f conical papillae
have been observed at the column and anther cap at the surface of the latter also villiform on
the lip obpyriform papillae and moniliform trichomes were found
n M. johniana raenzl M cf lehmanii chb f and M. sanderiana chb f obpyriform and
moniliform trichomes were observed on the lip according to the same authors t is clearly
shown that the presence of obpyriform and moniliform trichomes is typical of members of the
‘randiora omplex’ he presence of this particular type of the papillae is not surprising
since wherever pseudopollenforming trichomes occur labellar papillae tend to be obpyriform
n our research we have found other additional features such as
secretion conical and villiform papillae in both M. striata and M. molitor and elliptical papillae
in M. molitor
Conclusion
labrous labella are not common in Maxillaria and tend to occur mainly in species assigned to
the M. cucullata alliance s reported the
upper surface of the lip of M. chartacifolia mes chweinf is glabrous whereas the lower
is papillose and covered with obpyriform papillae n members of the M. rufescens alliance the
obpyriform papillae have been found on the labellar surface whereas those towards the center
of the lip are clavate and much larger with distended apices s
predicted multiseriate trichomes which have been known so far
only in M. camaridii chb f and M. pulchra chltr illiams ex orrell might be more
orphology and micromorphology of Maxillaria
important as taxonomic characters n recent years avies has become less convinced that the
multiseriate hairs of M. camaridii are trichomes but merely projections from the labellar surface
which migth be the reason why they bear papillae avies pers comm
pecies examined in this study have been classied in formal sections and one complex n all
taxa the presence of the papillae of various shapes has been demonstrated able he most
common shape of the papillae is obpyriform and those have been noticed on the labellar surface
of species including M. callichroma and M. luteoalba both from sect Aggregatae tzer
M. reichenheimiana sect Arachnites hristenson M. praestans sect Cucullatae hristenson
M. graminifolia and M. ramosa both placed in sect Ebulbes tzer M. ponerantha sect Erectae
tzer M. molitor probably sect Maxillaria uiz av M. ochroleuca sect Multiorae
hristenson M. aurea and M. purpureolabia both placed in sect Ornithidium alisb
hristenson M. marginata sect Repentes tzer M. rufescens sect Rufescens hristenson
M. vitelliniora sect Urceolatae hristenson and M. striata ‘randiora omplex’ onical
papillae have been found on the lip surface of species Maxillaria cucullata sect Cucullatae
M. graminifolia sect Ebulbes M. ponerantha sect Erectae M. molitor probably sect
Maxillaria M. aurea and M. purpureolabia both placed in sect Ornithidium M. picta and
M. cf mosenii both from sect Repentes M. vitelliniora classied most probably in section
Urceolatae hristenson and M. striata ‘randiora omplex’ illiform papillae were observed
also in species M. praestans sect Cucullatae M. graminifolia sect Ebulbes M. ponerantha
and M. tenuifolia both most probably from sect Erectae M. molitor probably sect Maxillaria
M. aurea sect Ornithidium M. picta sect Repentes M. vitelliniora sect Urceolatae
M. pterocarpa probably sect Trigonae hristenson M. striata ‘randiora omplex’ lavate
papillae have been noted on the lip of only species Maxillaria callichroma sect Aggregatae
M. ochroleuca sect Multiorae M. picta sect Repentes M. rufescens sect Rufescens lliptical
papillae occurred in one single species M. striata ‘randiora omplex’ richomes seem to
be limited to the species from sections M. callichroma and M. luteoalba sect Aggregatae
M. reichenheimiana sect Arachnites M. graminifolia sect Ebulbes M. ochroleuca sect
Multiorae M. marginata and M. picta sect Repentes eward in the form of pseudopollen
has been recorded in M. molitor and M. striata both from ‘randiora omplex’ esidues
of some kind of secretion we observed on the lip surface of M. callichroma sect Aggregatae
M. graminifolia sect Ebulbes M. tenuifolia probably sect Erectae M. molitor probably sect
Maxillaria M. marginata sect Repentes M. pterocarpa probably sect Trigonae and M. striata
‘randiora omplex’ apillae occurred also on the outer surface of the lip of M. graminifolia
sect Ebulbes M. molitor probably sect Maxillaria M. aurea and M. purpureolabia both
placed in sect Ornithidium and M. striata ‘randiora omplex’
he papillae of Maxillaria are highly adaptable and full a variety of functions
hey play a role as attractants and guides for visiting insects using a combination
of visual olfactory and tactile cues ince some of them are rich in aromatic amino acids they can
provide rewards in the form of nectar or a viscid waxlike material or may be a part of protection
from desiccation and herbivorous insects he exact function of the papillae in a particular species
can only be established for certain by observing how pollinators respond to them in the eld
ntil such data will be collected morphological studies can only
provide partial answers
Table 2. ummary of structures occurring on labellar epidermises of examined species pecies unplaced in any known
section by
apillae on the
bottom side
seudopollen
ecretion on the
inner surface
richomes
inner surface
apillae inner surface
onical
lavate
bpyriform
lliptical
illiform
ection Aggregatae
Maxillaria callichroma × × × ×
Maxillaria luteoalba ××
Maxillaria cf setigera* × × ×
Maxillaria cf triloris* × ×
ection Arachnites
Maxillaria reichenheimiana ××
Maxillaria buchtienii × × ×
Maxillaria fractiexa × × ×
Maxillaria lepidota × ×
Maxillaria lindleyana ×××
Maxillaria longissima × ×
Maxillaria pseudoreichenheimiana × ×
ection Cucullatae
Maxillaria cucullata ×
Maxillaria praestans ××
ection Ebulbes
Maxillaria graminifolia × × × × × ×
Maxillaria ramosa ×
ection Erectae
Maxillaria ponerantha ×××
Maxillaria tenuifolia* ××
Maxillaria procurrens ×
ection Multiorae
Maxillaria ochroleuca ×××
ection Ornithidium
Maxillaria aurea ××××
Maxillaria purpureolabia ×××
ection Repentes
Maxillaria marginata ×××
Maxillaria picta ××××
Maxillaria cf mosenii* ×
ection Rufescens
Maxillaria rufescens ××
ection Urceolatae
Maxillaria vitelliniora ×××
ection Trigonae
Maxillaria pterocarpa* ××
randiora omplex
Maxillaria striata* ××× × × ×
Maxillaria molitor* ××× × ×××
orphology and micromorphology of Maxillaria
Acknowledgements
he micromorphological studies carried out by the second author were supported by the ational
cience entre in oland grant number he authors are grateful to r evin
avies and rof ariusz zlachetko for their valuable comments and suggestions concerning
this paper and to arkus ngler oss ayton urt uzard ric unt aniel claren uis
enato ddie halen uiz ilipe arella ohn arigos for providing the illustrative pictures
of examined species
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ddress of the authors
onika ipińska corresponding author
epartment of lant axonomy and ature onservation
gnieszka owalkowska
epartment of lant ytology and mbryology
aculty of iology
niversity of dańsk
ita twosza
dańsk
oland
mail monikalipinska@biolugedupl
