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Bothalia. 12,3: 429-435 (1978)
Studies in the Hypoxidaceae. II. Floral morphology and anatomy
M. F. THOM PSON!
ABSTRACT
The inflorescence and flowers o f representatives of Spiloxene, Pauridia and Empodium were studied. The
inflorescence shows a reduction from a several-flow ered umbel to a single flower. The anthers are non-versatile
in all three genera, unlike those of Hypoxis and Rhodohypoxis. In Spiloxene and Pauridia the ovary is 3-locular
with axile placentation, while in Empodium it is unilocular with three parietal placentas. The floral vascular
anatomy of the three genera is described and the generic differences pointed out. The close relatio nship between
Spiloxene and Pauridia is dem onstrated and the inclusion o f Pauridia in the Hypoxidaceae is supported.
Spiloxene is regarded as generically distinct from Hypoxis.
RÉSUMÉ
ÉTUDES SUR LES H YPOXIDA CÉES: II. MOR PHO LOGIE ET AN ATOMIE FLO RALES
On a étudié Tinflorescence et les fleurs de représentants de Spiloxene, Pauridia et Empodium. L'inflorescence
montre une réduction d'une ombelle multiflorale á une fleur unique. Dans les trois genres, á la difference ^ ’Hypoxis
et Rhodo hypo xis, les anthéres sont non-versatiles. Chez Spiloxene et Pauridia I'ovaire est tri-loculaire avec une
placentation axile, tandis que chez Empodium i/ est uniloculaire avec trois placentas pariétaux. L'anatomie
vasculaire florale des trois genres est décrite et on signale les differences génériques. La forte affinité entre Spiloxen e
et Pauridia est démontrée et Tinclusion de Pauridia dans les Hypoxidacées est confirmée. Spiloxene est regardé
comme un genre distinct i/’Hypoxis.
1. INTRODUCTI ON
It was pointed out in the first part of this work
(Thompson, 1976) that the genera o f the Hypoxidaceae
are in need of taxonomic revision. The aim of these
contributions is to compare anatomical and morpho-
gical features of the genera Spiloxene, Empodium and
Pauridia with special reference to characters that
could be of taxonomic value. While the first paper
dealt with corm and leaf, the present contribution
discusses inflorescence and flower.
No previous work has been done on the floral
anatomy of South African Hypoxidaceae. Scharf
(1892) and Arber (1925) have remarked that the
vascular bundles of the peduncle lie in a ring, not
scattered as in the stems of most monocotyledons.
This observation can be explained by the fact that
the peduncle is not the main stem or axis, but an
axillary structure. Nel (1914) studied the morphology
of the inflorescence, flower and bracts of Spiloxene
(as Janthe) and determined which parts are peduncle
and which are pedicel.
2. MA TERIA L A N D M ETH ODS
The following species were studied: Spiloxene alba
(Thunb.) Fourc., S. aquatica (L.f.) Fourc., S. capensis
(L.) Garside, S. flaccida (Nel) Garside, S. minuta
(L.) Fourc., S. ovata (L.f.) Garside, S. schlechteri
(Bol.) Garside, S. serrata (Thunb.) Garside; Pauridia
minuta (L.f.) Dur. & Schinz, P. longituba M. F.
Thompson; Empodium plicatum (Thunb.) Garside,
E. veratrifolium (Willd.) M. F. Thompson.
Flowers of Pauridia minuta were fixed in FAA and
embedded in paraffin wax. Serial microtome cross
sections were made. They were stained with safranin
and fast green and mounted in Depex. The larger
flowers of Spiloxene and Empodium were fixed in FAA
and stored in 70 % alcohol before hand sectioning or
clearing.
The structure of the perianth segments, anthers and
stigmas was studied using hand sections of fresh
material stained with anilin chloride or safranin and
fast green.
The vascular anatomy was studied using clearing
techniques. The flowers were cleared by heating in pure
lactic acid (Sporne, 1948), or boiling in 60% lactic
* Forms part o f an M.Sc. thesis submitted to the University
of Stellenb osch (1972).
t Botanical Research Unit, P.O. Box 471, Stellenbosch.
acid. The tracheary and parenchymatous tissues were
contrasted by condenser-iris-diaphragm regulation on
a compound microscope. Fresh or preserved material
was used. In addition to cleared material, cross
sections were studied—either hand sections or, in
Pauridia, serial microtome sections.
3. MOR PHOL OGY
(1) The Inflorescence
Spiloxene
In Spiloxene the flowers are pedicellate and are
borne on peduncles, which arise from the corm in the
axils of the leaves. Nel (1914) maintained that in the
species with two bracts and those with many flowers
e.g. S. aquatica the peduncles arise terminally. In
all the species studied, including S. aquatica, I found
the peduncles to be axillary.
The peduncles may be one-flowered (e.g. S. capensis)
to several-flowered (e.g. S. aquatica). In the latter
case, the inflorescence is an umbel-like raceme. At the
junction of the peduncle and the pedicel(s) one or two
bracts occur. These may be small and setaceous (as in
S. serrata) or linear-lanceolate foliaceous bracts as in
S. capensis.
A many-flowered inflorescence is, in general, con
sidered to be more primitive than the single flower
which arises by reduction (Eames, 1961). The umbel
like inflorescence of the many-flowered forms of
Spiloxene may be taken to be the most primitive condi
tion from which there are grades of reduction.
S. aquatica has two to seven flowers in an umbel with
two foliaceous bracts. S. flaccida has two or three
flowers, also with two foliaceous bracts. S. schlechteri,
S. serrata and S. minuta have one or two flowers,
while S. capensis and S. ovata have a single flower.
The single-flowered forms o f S. schlechteri, S. minuta
and S. capensis have one foliaceous bract, while
S. ovata and S. serrata have two setaceous bracts.
Thus there is a reduction in number or in size of the
bracts, as well as in the number of flowers.
Pauridia
The genus has an axillary inflorescence, like the
single-flowered species of Spiloxene, with two
setaceous bracts at the junction between peduncle and
pedicel. In P. longituba the pedicel is very short
(1-2 mm) and exceded by the bracts (2-10 mm), while
in P. minuta it is longer than the bracts.
430 STUDIES IN THE HYPOX IDACEAE. II. FLORAL MORPHOLOGY A ND ANATO MY
TA BLE 1.—Reduction in the inflorescence in Spiloxene
Species
Nu mber of
flowers in
inflores
cence
Number
of
bracts
Na ture of
bracts F.
foliaceous
S. seta
ceous
Filaments
E. equal
U. un
equal
S. aquatica.. . 2-7 2F E
S. flaccida. .. . 2-3 2F U
S. alba
............
1-2 2Fu
S. schlechteri. 1-2 1-2 Fu
S. serrat a. . .. 1-2 2S E
S. minuta. . . . 1-2 1FE
S. ovata
..........
12SE
S. capensis... 11FE
Emp odium
The flowers are axillary and borne singly. As there
is no division into peduncle and pedicel, there are no
bracts. The pedicels may be long as in E. veratrifolium
or short and hidden within the sheathing leaves as in
E. plicatum. In the latter case, the pedicel elongates
during the fruiting stage thus the fruits are exserted
from the sheath.
(2) Perianth
Spiloxene
The flowers are regular with two whorls of three free,
subequal more or less lanceolate perianth segments
spreading from the top of an inferior ovary. The
segments of the inner whorl are generally smaller than
those of the outer whorl. The adaxial surface is white
or yellow with or without a dark spot at the base and
the abaxial surface is often striped or tinged with green
or m aroon. In S. capensis there may be an irridescent
spot at the base of the perianth segments. Some
attempts have been made to define varieties based on
the variation in size and colour of these spots; however,
as Garside (1924) concluded, these variations are of a
‘continuous’ kind and varieties are better based on
vegetative characters. A single population (e.g.
Thompson 2939) may have flowers without spots,
with dark spots of various sizes or iridescent “ pea
cock” spots.
Pauridia
Pauridia has a regular perianth with a distinct tube.
Geerinck (1969) incorrectly describes Pauridia as
having free tepals. In P. minuta the tube is short
(up to 5 mm) and equal to or less than the length of the
lobes. In P. longituba it is up to 20 mm long and
approximately three times the length of the lobes.
The lobes are subequal, narrowly ovate. The outer
lobes have a small hooded tip with papillae on the
inside. The reverse sides (abaxial) of the segments are
green at the tip fading downwards, with the outer
segments being darker.
Empodium
The perianth has six free lanceolate equal segments,
which spread from the top of the ovary beak. In a
flower opening for the third and fourth day the seg
ments may become reflexed.
(3) Androecium
Spiloxene
There are two whorls of three free stamens attached
to the base of the perianth segments. The filaments
may be equal, e.g. S. capensis, or unequal in length,
e.g. S.flaccida. (Table 1).
The anthers are linear 2-thecous, basifixed and non-
versatile, i.e. the filaments are continuous with the
connectives between the thecae without a joint or
articulation. In Hypoxis and Rhodohypoxis the anthers
are distinctly versatile. The terminology applied to the
anther attachment has caused some confusion (Geer
inck, 1969). However, the presence or absence of an
articulation, a character very clearly seen in fresh
material, is the distinguishing feature. The thecae open
by longitudinal slits.
Pauridia
Pauridia has three stamens inserted on the perianth
tube opposite the inner perianth segments. The anthers
are 2-thecous. split longitudinally and are basifixed.
The thecae separate from the connective at the top
and bottom, thus the anther appears lobed.
Empodium
Here there are six free stamens with short equal
filaments attached to the base of the perianth segments.
The anthers are linear, 2-thecous, opening by longi
tudinal slits, basifixed, non-versatile. Some species of
Empodium have caudate appendages on the anthers.
(4) Gynoecium
Spiloxene
There are three free or fused, commissural stigmas
borne on a very short style. The ovary is normally
three-locular with axile placentation and numerous
ovules. Sometimes the septa do not extend to the top of
the ovary, leaving the top part unilocular, as in
S. aquatica. The ovary is usually slightly constricted
below the perianth (most noticeable in the fruiting
stage). In S. alba this constriction forms a neck, from
the top of which the perianth segments and stamens
arise. The fruit is a capsule with circumcissile dehis
cence or irregular fragmentation.
Pauridia
In Pauridia the stigma is 6-lobed with three long,
erect, commissural lobes and three short recurved
lobes or appendages over the ovary chambers. Some
or all of the lobes occasionally abort. A freak flower
(in Thompson 278) tended to form anthers on the short
lobes, one almost complete. The style is short in
P. minuta and long in P. longituba in direct relationship
to the length of the perianth tube.
The ovary is 3-locular with numerous ovules and
axile placentation. The fruit may be a capsule with
circumcissile dehiscence (P. minuta) or be thin walled
with irregular fragmentation (P. longituba). Two
similar forms of fruit have been recorded within the
genus Rhodohypoxis (Hilliard & Burtt, 1973).
Empodium
This genus has three subulate stigmatic lobes on a
short style, except in E. gloriosum (Nel) B. L. Burtt.
The ovary is unilocular with parietal placentation and
develops into a slightly succulent, indehiscent fruit.
In some species, e.g. E. plicatum, the pedicel being
short the ovary is enclosed within the leaf sheath.
The pedicel elongates exposing the fruit. In others, e.g.
E. veratrifolium, the pedicel being long the ovary and
fruit are exposed. Many of the species have a long
ovary beak or neck. This is a solid prolongation of the
ovary or, possibly, the receptacle, which bears
perianth and androecium. The length of the beak is
inversely related to the length of the pedicel.
(5) Comparison
Of the three genera Spiloxene has the simplest basic
flower structure. Empodium differs from Spiloxene in
having no bracts on the peduncle, a one-chambered
ovary, an indehiscent fruit and in the development of
M. F. THOMPSO N 43 1
TA BLE 2.— Comp arison o f morph olog ical characters
Organ Spiloxene Pauridia Empodium Hypoxis Rhodohypoxis
Rootstock
.............................
Corm
....................... Corm ....................... Corm
......................
Tu berous rhizome Tuberous rhizom e
Pubescence
............................ Glabrous or few Glabrous................ Glabrou s or sim ple P ubescent with Pubescent with
sim ple hairs hairs como und hairs compoun d hairs.
Inflorescence
........................
1-7-flowered um l(or2)-flo w ered.. . 1-flowered
.............
1- several-flowered 1-2-flowered.
bellate raceme
Bracts...................................... 1 or 2
.....................
2 ................................ 0
...............................
1 per flow er
.........
1 or 2.
Perianth segm ents
.............
Free
.......................... Tube
........................
Free
.........................
Free
.......................... Tu be and “ blind
lo o k ”.
No. stam ens
........................
6 ................................ 3 ................................ 6
...............................
6 ................................ 6
Anthers
..................................
Non-versatile
........
Non-versatile
........
Non-versatile
........
Versatile
.................
Versatile.
Stigm a.................................... 3-lobed
....................
6-Iobed
....................
3-lobed.................... 3-grooved
...............
3-lobed.
Ovary
.....................................
3-locular
.................
3-locular
.................
1-locular
.................
3-locular.
Placentation.......................... Axile
........................
Axile
........................
Parietal
...................
Axile.
an ovary beak in many species. Pauridia differs from
Spiloxene in having a perianth tube, only 3 stamens
and a six-lobed stigma.
The differences are summarized in Table 2.
4. A NA TO MY
(1) Soft tissues
The three genera show little difference in the
anatomy of the soft tissues of the perianth, stamens
and gynoecium. The following description applies
to all three unless otherwise stated.
Perianth
The upper (adaxial) epidermal cells o f all three
genera have strongly convex or dome-shaped outer
walls. The cells are from 30 m high in P. minuta to
70 /Ltm in Empodium plicatum. The cuticle is rough with
striations radiating from the highest point of the cell.
In surface view the cells are isodiametric over the
greater part of the perianth segment and become
elongated towards the base of the segment. The outer
cell walls also flatten out towards the base and on the
tube in Pauridia.
The abaxial epidermal cells do not have markedly
convex outer walls. The cells are elongated along the
long axis of the segment. The anticlinal walls are
undulate in Empodium, but smooth in Spiloxene and
Pauridia. The cuticle is smooth and scattered stom ata
occur.
In the yellow-flowered species the adaxial epidermal
cells contain chromoplasts which are lacking in the
white flowers. In most species the abaxial subepidermal
cells contain numerous chloroplasts. These may be
restricted to the cells near the veins, e.g. in P. minuta
which as a green stripe down the centre of the abaxial
side of each segment. In species with maroon backs to
the segments e.g. S. schlechteri, the chloroplasts are
present in the subepidermal layer and the cell-sap of
the abaxial epidermal cells is coloured red (presumably
with anthocyanin).
The mesophyll is generally about ten cells deep and
consists of irregularly shaped cells with intercellular
spaces. Scattered raphide-containing cells occur.
Stamens
The single trace of the filament continues into the
connective which, like the filament, consists of paren
chymatous tissue covered with a smooth epidermis.
The anthers dehisce by means of longitudinal slits.
The endothecial cells have secondary wall thickenings
in the form of strips on the anticlinal and inner
periclinal walls. Cells with similar thickenings extend
into the ground tissue of the connective near the junc
tion of the two pollen sacs on each side of the anther.
Stigma
The three lobes of the stigma in Spiloxene and
Empodium have papillose edges which form the recep
tive surfaces. The pollen frequently germinates on the
papillae and the pollen tube grows down the outside of
a papilla and into the stigmatic tissue at the base of the
papilla.
In Pauridia the long lobes of the stigma are similar
to those in Spiloxene. The short lobes do not have
papillae, but pollen is received in the small adaxial
groove and has been observed to germinate there.
(2) Vascular anatomy
Spiloxene (Fig. 1)
The vascular anatomy of the flowers of S. aquatica,
S. capensis, S. schlechteri and S. serrata differs only
slightly in small details such as the actual position of
branching. The following description applies to
S. aquatica.
The hollow pedicel has six vascular bundles. Well
below the ovary the outer three bundles give off two
subopposite side branches (lp: Fig. 1.2), and then
continue free up the ovary to become the median
bundles (op: Fig. 1.3) of the outer Perianth segments.
The side branches (lp) run free to the bases of the
perianth segments where each divides to form the
lateral veins (lpb: Fig. 1.9) of adjacent segments.
In the outer segments they branch again to give a total
of five to nine veins in a segment. According to
Fraenkel (1903) members of the Hypoxidaceae have a
vascular arrangement in the perianth segments
belonging to his group III, i.e. with one median nerve
and two equal independent free ending side nerves.
The inner three pedicel bundles form a bundle
complex just below the ovary (comp: Fig. 1.3). From
this complex run: (i) the ventral carpel bundles (vc:
Fig. 1.4) which run up the median axis and supply
the ovules (vcb: Fig. 1.5); (ii) the lateral carpel bundles
(lc: Fig. 1.4-1.7) which lie in the ovary wall opposite
the septa and which comprise the fused lateral carpel
bundles, inner perianth segment median traces (ip:
Fig. 1.8) and inner stamen traces (ia: Fig. 1.8) (iii)
the dorsal carpel bundles (dc: Fig. 1.4 and 1.5) which
lie close to the outer perianth trace (op) on the same
radius. The dorsal carpel bundle includes the outer
staminal trace (oa: Fig. 1 .6-1.9) which branches off
near the top of the ovary. The dorsal carpel bundle
continues into the style (g: Fig. 1 .6-1.9 ) where it
divides to supply two adjacent stigmatic lobes (gx & g2).
This supply is normal in commissural stigmas (Eames,
1961), since the stigma lobes are formed from two
halves of adjacent carpels and lie opposite the inner
perianth segments and over the ovary septa.
<Ji cor^ c$
432 STUDIES IN THE H YPOXID ACEAE. II. FLORAL MORPHOLOGY A ND ANATO MY
Fig. 1.—Vascular anatomy of the flower o f Spiloxene aquatica sho wing one diagrammatic longitudin al section and nine sections
taken at the levels indicated on the longitudin al sec tion, com p, bundle com plex; dc, dorsal carpel bundle; g, style bu ndle;
g! and g2 branches of the style bundle; ia, inner stam en trace/bundle; ip, inner perianth bundle; lc, lateral carpel bundle;
Ip, lateral perianth bundle; lpb, branch o f lp; oa, outer stamen bu ndle; op, outer perianth m edian bundle; vc, ventral
carpel bundle; vcb, branches of the ventral carpel bundle.
Fig. 2.— Vascular anatomy of the flower o f Pauridia minuta. ab, stam en bundle; com p, bundle c omp lex; dc, dorsal carpel bundle^
g, style bundle; ip, inner perianth bundle; lc, lateral carp el bundle; lp, lateral perianth bundle; op , outer perianth bund le;
vc, ventral carpel bundle.
M. F. THOMPSON 433
Pauridia minuta (Figs 2 and 3A)
The peduncle has three vascular bundles. At the
node between this and the pedicel a trace leads to each
of the opposite bracts. The solid pedicel, i.e. above the
bracts, has six bundles (Fig. 2.1).
Three of these bundles represent the dorsal carpel
traces (dc) which at this level (Fig. 2.1 and 2.2)
comprise the dorsal carpel bundles, the outer perianth
segment median traces (op) and the lateral perianth
traces (lp). Near the base of the ovary (Fig. 2.3) each
dorsal bundle gives off two side branches, the lateral
perianth bundles (Ip) which dichotomise at the top of
the perianth tube to form the lateral veins of two
adjacent perianth segments—one outer and one inner
(Fig. 2.8 ; 3A). The dorsal carpel bundles give off the
median bundles (op) of the outer perianth segments
(OP) at the top of the ovary (Fig. 2.6) and continue as
the style bundles(g). These latter divide into three, the
central branch supplying the appendages or short
stigma lobes and the two side branches going to
adjacent commissural long lobes. The two bundles in a
long lobe (from different dorsal carpel bundles) may
fuse to form one.
The remaining three pedicel bundles anastomose in
the receptacle area to form a bundle complex (comp:
Fig. 2.2). This gives rise to: (i) the ventral carpel
bundles (vc) which run up the central axis and supply
the ovules, but do not continue into the style; (ii) the
lateral carpel bundles (lc) which later give rise to the
inner perianth segment median traces (ip) and the
staminal traces (ab). The division into these bundles
occurs just above the top of the ovary (Fig. 2.2-2.6).
Pauridia differs from Spiloxene in that the dorsal
carpel bundle (dc) and outer perianth trace (op) are
fused and run from the pedicel to the top of the ovary
without forming p art of the bundle complex below
the ovary chambers. The vascular supply of the short
stigma lobes is basically the same as that o f the outer
stamens in Spiloxene. This, and their position, could
indicate that the short lobes are reduced stamens.
Fig. 3.— Vascular anatomy of the
flow er. A, Pauridia minuta—
part o f ovary wall and
perianth slit longitudinally
and spread out (central axis
and ovules removed). B,
Empodium plicatum— part of
ovary wall slit longitudinally
and spread out. ab, stam en
bundle; dc, dorsal carpel
bundle; g, style bundle; ia,
inner stamen bundle; IP,
inner perianth segm ent; ip,
inner perianth bundle; lc,
lateral carpel bundle; lp,
lateral perianth bundle; oa,
outer stam en bundle; OP,
outer perianth segment; op,
outer perianth bundle; plac,
placental bundle; vc, ventral
carpel bundle.
Fig. 4.— Vascular anatom y o f the
flower o f Empodium plicatum.
dc, dorsal carpel bundle; g,
style bundles; ia, inner
stamen bundle; ip, inner
perianth bundle; lc, lateral
carpel bundle; lp, lateral
perianth bundle; oa, outer
stam en bundle; op, outer
perianth bundle; plac,
placental supply; vc, ventral
carpel bundle.
434 STUD IES IN THE HYPOXIDA CEAE. II. FLORAL MORPHOLOGY AND ANATOM Y
Empodium plicatum (Figs. 3B and 4)
The solid pedicel has six vascular bundles (Fig. 4.1)
which become the three dorsal carpel traces (dc) and
three ventral-lateral carpel traces (vc+lc). Just below
the ovary the ventral-laterals give off two branches
which run undivided up the ovary and beak, as the
fused lateral carpel and lateral perianth traces (lc+ lp
Figs. 3B and 4 .2-4.6). At the base of the perianth
segments (Fig. 4.7) they divide to form the lateral
bundles o f adjacent perianth segments (lp). In the
segments they divide again to form additional parallel
veins.
The dorsal carpel bundles (dc) comprise the fused
dorsal carpel, outer perianth median bundle and outer
stamen traces (dc +op +oa ). At the top of the ovary
the dorsal carpel bundle continues as the style bundle
(g). The outer perianth and outer stamen traces remain
fused to about two-thirds of the way up the beak where
the division into the outer stamen trace (oa) and
median bundle of the outer perianth segment (op)
occurs (Fig. 4.6).
At the base of the ovary the ventral-laterals (vc+ lc)
divide to give rise to: (i) the ventral carpel bundles (vc)
which represent the fused ventral carpel, inner perianth
and inner stamen traces (v c+ip +ia ); alm ost imme
diately these bundles give off two branches to the
placentas (plac) which supply the ovules and end at
the top of the ovary, (ii) Two fused lateral carpel and
lateral perianth traces (lc+ lp: Figs 3B and 4.2).
Where the ovary grades into the beak (Fig. 4.4 and
4.5) the ventral-carpel bundles (vc) divide into the
style traces (g) and the fused inner perianth and inner
stamen bundle (ip+ia). The style traces (g), with the
three traces from the dorsal carpel bundles, run up the
centre of the beak into the style and stigma, two
bundles going to each stigmatic lobe (Fig. 4 .5-4.8).
The inner perianth and inner stamen traces remain
fused up to the same level as the outer perianth and
stamen traces, where they divide to form the inner
staminal bundle (ia) and the median bundle of the
inner perianth segment (ip: Fig. 4.6).
Apart from the modification related to the elonga
tion of the ovary into a beak and the parietal placen
tation, Empodium differs from Spiloxene and Pauridia
in: (i) lacking a bundle complex below the ovary:
(ii) the supply to the style and stigmas—here the six
bundles are branches, alternately, of the dorsal and
ventral carpel bundles, whereas in Spiloxene and
Pauridia only the dorsal bundles supply the style,
each bundle dividing again; (iii) the perianth supply.
Here the traces to the perianth, stamens and carpels
are fused in the ovary wall, whereas in Spiloxene the
traces to the outer perianth segments are free. Here the
lateral bundles of the perianth are fused to the ventral
lateral carpel bundles at the base. In Spiloxene they
arise from the outer perianth trace.
5. D ISC USS IO N A ND C ON CLUSIO NS
This study of the floral morphology and anatom y,
with that of the vegetative parts (Thompson, 1976)
confirms the close relationship between Spiloxene and
Pauridia. The inflorescence and bracts of Pauridia
are similar to those of some species of Spiloxene. Both
genera have a 3-locular ovary with axile placentation
and similar fruits.
The anatomy, of the soft tissues shows little
difference, while in vascular anatom y Pauridia differs
from Spiloxene in that the dorsal carpel bundle (dc)
and outer perianth trace (op) are fused and run from
the ped.cel to the top of the ovary without forming
part of the bundle complex below the ovary chambers.
Pauridia shows a reduction in the number of stamens
from six (3 + 3) to three, lying opposite the inner
perianth segments. It is possible that the three short
lobes of the stigma represent reduced stamens which
have become fused to the gynoecium. Their vascular
supply is basically the same as that of the outer
stamens of Spiloxene. A freak flower (in Thompson
278) tended to form anthers on the short lobes, one
alm ost complete. An undescribed species of Spiloxene
has four perianth segments and two stamens; the
stamens fused to the style. The fusion (connation) of
the perianth segments to form a perianth tube in
Pauridia is an advanced feature.
Empodium shows more marked differences from
Spiloxene. The inflorescence always consists of a
single flower without bracts. There is no distinction
into peduncle and pedicel. Empodium has a unilocular
ovary with parietal placentation and forms an indehis-
cent fruit. The parietal condition is not generally
regarded as having been derived from the axile but
rather that both developed independently from the
submarginal type (Eames 1961).
The prolongation of the ovary into a neck or beak,
a common feature in Empodium is also found in
Spiloxene (e.g. S. alba and an undescribed species).
Hilliard & Burtt (1973) discuss the value of the
ovary beak as a generic character in relation to
Empodium and Curculigo and Rhodohypoxis.
The vascular anatomy of Empodium differs from the
others in the lack of a bundle complex, the style
being supplied by dorsal and ventral carpel bundles
and in the fusion of the median perianth traces to the
dorsal carpel bundle and the lateral perianth traces to
the ventral-laterals.
Spiloxene has been included in Hypoxis by various
authors such as Baker (1896) and Geerinck (1969).
I disagree with this arrangement on grounds of
differences in the rootstock, hairiness, leaf arrange
ment, inflorescence, manner in which the anthers are
borne and geographical distribution.
The South African genera in the family fall into
two groups, which do not warrant sub-family status.
Hypoxis and Rhodohypoxis are closely related, while
Spiloxene, Pauridia and Empodium form the other
group with Spiloxene and Pauridia most closely related.
Of the characters found in the floral morphology
and anatomy, the form of the ovary, number of locules
and placentation, the number of stamens appear the
most im portant taxonomically. The vascular anatom y
has confirmed generic relationships and differences.
ACKNOW L EDGEM E N TS
I wish to express my sincere thanks to Prof. M. P. de
Vos, who prom oted this study for an M.Sc. thesis and
read the manuscript of these two papers; also Mr
E. G. H. Oliver for reading the manuscripts.
UITTREKSEL
Die bloeiwyse en blomme van verteenwoordigers van
Spiloxene, Pauridia en Empodium is bestudeer. Die
bloeiwyse toon ’n reduksie van ’n skerm met verskeie
blomme tot ’n enkele blom. Die helmknoppe is onbe-
weeglik by al drie genera, anders as by Hypoxis en
Rhodohypoxis. By Spiloxene en Pauridia is die
vrugbeginsel 3-hokkig met asstandige plasentasie,
terwyl by Empodium dit eenhokkig is met drie rand-
standige plasentas. Die anatomie van die vaatstelsel
by die blomme van die drie genera is beskryf en die
generiese verskille is demonstreer. Die nou verwantskap
tussen Spiloxene en Pauridia is demonstreer en die
insluiting van Pauridia in die Hypoxidaceae is onder-
steun. Spiloxene word beskou as generies verskillend
van Hypoxis.
M. F. THOMPSON 435
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