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Inflorescence and early flower development in the East Asian Dioscorea tokoro were investigated using scanning electron microscopy (SEM). The synflorescence is typically a raceme of open thyrses. Lateral units of thyrses are cincinni, which in female plants are often replaced by single flowers with a bracteole. Phyllotaxy of thyrse axis follows the...
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... main inflorescence axis possess axillary complexes that initiate, develop and proceed to flowering in an acropetal sequence. Each axillary complex contains a descending series of buds (occurrence of two buds was most common in our material). In most cases, all buds of a serial complex develop structures of the same type, namely, open thyrses ( Fig. 1). Sometimes, more complex structures can be seen. For example, the first bud of a serial complex may develop a shoot with one or two lateral thyrses followed by a terminal ...
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... development of female flowers is very similar to that in male flowers (Figs. 10 -12). More precisely, the flowers are functionally female, because they always possess six staminodes in the same positions as stamens of male flowers. Until the stage of gynoecium initiation, the staminodes of functionally female flowers are nearly identical to the stamens of male flowers of the same developmental stage. In later stages, ...
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... the stage of gynoecium initiation, the staminodes of functionally female flowers are nearly identical to the stamens of male flowers of the same developmental stage. In later stages, the staminodes develop two small thecae (Figs 13, 14), but do not differentiate microsporangia recognizable in surface view. ...
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... in male flowers, the first tepal initiates on the radius opposite the bracteole, and two other outer whorl tepals initiate to the left and to the right of the bracteole (Fig. 10A, B, Fig. 11A-D). The flower meristem is clearly convex at this stage. Close association between the inner whorl stamens and inner whorl tepals of the same radii appears to be even more pronounced than in male flowers (Fig. 10D, Fig. 11G -I). Some images clearly suggest the occurrence of three common primordia, each giving rise to a staminode and a ...
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... radius opposite the bracteole, and two other outer whorl tepals initiate to the left and to the right of the bracteole (Fig. 10A, B, Fig. 11A-D). The flower meristem is clearly convex at this stage. Close association between the inner whorl stamens and inner whorl tepals of the same radii appears to be even more pronounced than in male flowers (Fig. 10D, Fig. 11G -I). Some images clearly suggest the occurrence of three common primordia, each giving rise to a staminode and a tepal (Fig. 11E, F). On later stages, these two organs are basally united (Fig. ...
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... 11A-D). The flower meristem is clearly convex at this stage. Close association between the inner whorl stamens and inner whorl tepals of the same radii appears to be even more pronounced than in male flowers (Fig. 10D, Fig. 11G -I). Some images clearly suggest the occurrence of three common primordia, each giving rise to a staminode and a tepal (Fig. 11E, F). On later stages, these two organs are basally united (Fig. ...
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... association between the inner whorl stamens and inner whorl tepals of the same radii appears to be even more pronounced than in male flowers (Fig. 10D, Fig. 11G -I). Some images clearly suggest the occurrence of three common primordia, each giving rise to a staminode and a tepal (Fig. 11E, F). On later stages, these two organs are basally united (Fig. ...
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... between the inner whorl staminodes is smaller than the size of a staminode at this stage. During next stages, the receptacle between stamens becomes strongly concave. The shape of the concave part is triangular in outline (when the flower is observed in a top view), with angles on the radii of the outer whorl staminodes. In a young gynoecium (Fig. 13), plicate carpels can be seen on the radii of the outer whorl staminodes. Upper parts of carpels are free from each other but largely congenitally united with the concave receptacle (Fig. 13B, C). The lower part of the young gynoecium should be probably interpreted as a unilocular symplicate zone. A developed gynoecium consists of three ...
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... part is triangular in outline (when the flower is observed in a top view), with angles on the radii of the outer whorl staminodes. In a young gynoecium (Fig. 13), plicate carpels can be seen on the radii of the outer whorl staminodes. Upper parts of carpels are free from each other but largely congenitally united with the concave receptacle (Fig. 13B, C). The lower part of the young gynoecium should be probably interpreted as a unilocular symplicate zone. A developed gynoecium consists of three plicate stigmas, a common style, and an inferior ovary (Fig. 14). Figure 10. Dioscorea tokoro, development of functionally female flowers with right hand position of the bracteole. All images ...
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... the outer whorl staminodes. Upper parts of carpels are free from each other but largely congenitally united with the concave receptacle (Fig. 13B, C). The lower part of the young gynoecium should be probably interpreted as a unilocular symplicate zone. A developed gynoecium consists of three plicate stigmas, a common style, and an inferior ovary (Fig. 14). Figure 10. Dioscorea tokoro, development of functionally female flowers with right hand position of the bracteole. All images show first flowers of a cincinnus. A, bracteole is initiated, and the first outer whorl tepal is visible on the opposite radius. B, bracteole and all three outer whorl tepals are initiated; primordia of outer ...
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... developed gynoecium consists of three plicate stigmas, a common style, and an inferior ovary (Fig. 14). Figure 10. Dioscorea tokoro, development of functionally female flowers with right hand position of the bracteole. ...
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... data show a correlation between direction of the phyllotactic spiral on the axis of a thyrse and the handedness of lateral cincinni inserted along the thyrse axis (Fig. 2). If the phyllotaxy on Figure 11. Dioscorea tokoro, development of functionally female flowers with left hand position of the bracteole. ...
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... anodic end of a leaf is oriented in the direction up the genetic spiral of phyllotaxy towards the younger end while the cathodic end is oriented towards the beginning of the genetic spiral (Korn 2006). In these terms, the bracteole of the first flower of a cincinnus (or a solitary Figure 12. Dioscorea tokoro, development of functionally female flowers with left hand position of the bracteole (continued from Fig. 11). ...
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... spiral of phyllotaxy towards the younger end while the cathodic end is oriented towards the beginning of the genetic spiral (Korn 2006). In these terms, the bracteole of the first flower of a cincinnus (or a solitary Figure 12. Dioscorea tokoro, development of functionally female flowers with left hand position of the bracteole (continued from Fig. 11). A-B, young flowers at stages before elongation of tepals; any signs of gynoecium are yet absent. Note that inner whorl tepals and inner whorl staminodes of the same radii are basally united. C, bracteole is considerably elongated; the first formed outer whorl tepal is the largest one. D, flower bud with tepals and bracteole covering ...
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... in some other cases, growth of the cathodic side is delayed. For example, in inflorescences Theligonum cynocrambe (Rubiaceae), where phyllotaxy follows the Lucas pattern, anodic stipules are more vigorous than cathodic ones, at least in early Figure 13. Dioscorea tokoro, late stages of development of functionally female flowers. ...
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... of inflorescence structure in Theligonum cynocrambe. Occurrence of a stabilized anodic/cathodic asymmetry, at least in some cases, might be of a phylogenetic significance. Another member of Dioscoreales, Metanarthecium luteo-viride does not possess this feature. Both left and right bracteole position can be found in the same inflorescence (see Fig. 15). In Nymphaeales, stabilized anodic/cathodic asymmetry is found in Nymphaeaceae (e.g., flower insertion is anodic to the putative subtending leaf in Victoria and cathodic in Euryale -Cutter 1961; Schneider et al. 2003), but not in Hydatellaceae, at least in perennial species ( Sokoloff et al. ...
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... All leaves on the main inflorescence axis possess axillary complexes that initiate, develop and proceed to flowering in an acropetal sequence. Each axillary complex contains a descending series of buds (occurrence of two buds was most common in our material). In most cases, all buds of a serial complex develop structures of the same type, namely, open thyrses (Fig. 1). Sometimes, more complex structures can be seen. For example, the first bud of a serial complex may develop a shoot with one or two lateral thyrses followed by a terminal thyrse. Internodes on the main axis of each thyrse (= the second order axes of the synflorescence) are elongate. Phyllotaxy on second order axes of synflorescence starts with two transversal phyllomes (which can be classified as prophylls) and then follows the Fibonacci pattern (Fig. 2). Each ...
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... The arrangement and development of floral organs is unidirectional. The outer ring develops first and then the inner ring matures [25,26]. Research shows that understanding the characteristics and stages of plant flower bud differentiation and ensuring the quality and quantity of plant flower buds are of great significance to production [27]. ...
Lespedeza davurica (Laxm.) is a leguminous plant with significant ecological benefits, but its embryonic development mechanism remains unclear. We investigated the flower bud differentiation, megaspore and microspore formation, gametophyte development, and embryo and endosperm development in L. davurica. Our aim was to elucidate the relationship between the external morphology and internal development processes of male and female floral organs during growth, as well as the reproductive factors influencing fruiting. The results indicated that although the pistil develops later than the stamen during flower bud differentiation, both organs mature synchronously before flowering. L. davurica pollen exhibits three germination grooves, a reticulate outer wall, and papillary structures on the anther surface. In vivo pollination experiments revealed abnormal spiral growth of L. davurica pollen tubes within the style and the occurrence of callus plugs, which may reduce the seed setting rate. The anther wall development follows the dicotyledonous type, with tetrads formed through microspore meiosis exhibiting both left–right symmetry and tetrahedral arrangements. L. davurica has a single ovule, and the embryo sac develops in the monosporic polygonum type. After dormancy, the zygote undergoes multiple divisions, progressing through spherical, heart-shaped, and torpedo-shaped embryo stages, culminating in a mature embryo. A mature seed comprises cotyledons, hypocotyl, embryo, radicle, and seed coat. Phylogenetic tree analysis reveals a close genetic relationship between L. davurica and other leguminous plants from the genera Lespedeza and Medicago. This study provides valuable insights into the regulation of flowering and hybrid breeding in leguminous plants and offers a new perspective on the development of floral organs and seed setting rates.
... The different positions of the anther thecae in the stamens of the different whorls was described in D. tokoro (Remizowa et al. 2010), but the authors did not consider this peculiarity is linked with the massiveness of the connective. The species-specific structure of the stamens was also noted by Chung and Chung (2015), who examined the flower morphology in six species: D. polystachya Turcz., D. japonica Thunb., D. nipponica, D. quinqueloba (= D. quinquilobata), D. tenuipes, D. tokoro, four of which belong to the section Stenophora. ...
The section Stenophora is the most basal clade in the phylogeny of the genus Dioscorea. Most of the species in the section have not been morphologically and embryologically investigated and phylogenetic relationships among species of this section are not very clear. Embryological features, such as the structure of anthers, pollen, ovules, embryo sacs etc., less undergo phenotypic variability and can be used as important characters for systematics and phylogeny. Comparative morphological and embryological analyses of the reproductive structures in 5 Dioscorea species of the section Stenophora (D. balcanica, D. caucasica, D. deltoidea, D. nipponica, D. villosa) are presented. Four characters, which may be significant for systematics of this section as well as the whole genus Dioscorea, were designated: (1) heteromorphism of the stamens in the male flower; (2) the structure of the stigma; (3) the structure of the ovule; (4) the type of female gametophyte development. It was shown that D. balcanica, D. caucasica, D. deltoidea are characterized by similar morphological features and differ from D. nipponica and D. villosa. Analysis of haplotype networks showed that the section Stenophora consists of genetically close species, that was confirmed by the phylogenetic tree of this section. The morphological similarity of D. balcanica, D. caucasica and D. deltoidea is consistent with their location on the phylogenetic tree. However, detailed morphological, embryological and molecular phylogenetic studies of a larger number of species are needed for more accurate interpretation of the Stenophora phylogenetic system.
... However, these data can also be interpreted as early congenital fusion (see Box 1) between carpels, which is well documented in some monocots with undoubtedly tricarpellate gynoecia when their individual free tips appear in ontogeny after the appearance of the common triangular-tubular base of the gynoecium (e.g. Dioscorea, Dioscoreales: Remizowa et al., 2010a;Tricyrtis, Liliales: Remizowa et al., 2010b). In Costus (Zingiberales), the primordia of the two posterior-lateral carpels are initiated as congenitally united with each other, but free from the primordium of the anterior carpel (Kirchoff, 1988). ...
The grass family (Poaceae) includes cereal crops that provide a key food source for the human population. The food industry uses the starch deposited in the cereal grain, which develops directly from the gynoecium. Morphological interpretation of the grass gynoecium remains controversial. A bistigmatic grass gynoecium has two sterile carpels, each producing a stigma, and a fertile carpel that lacks a stigma. To date, studies of grass developmental genetics and developmental morphology have failed to fully demonstrate the composite nature of the grass gynoecium because its complex evolutionary history is hidden by extreme organ integration. We reexamine earlier hypotheses and studies of morphology and development in the context of more recent analyses of grass phylogenetics and developmental genetics. Taken in isolation, data on gynoecium development in bistigmatic grasses do not contradict its interpretation as a solitary ascidiate carpel. Nevertheless, in the context of other data, this interpretation is untenable. Broad comparative analysis in a modern phylogenetic context clearly demonstrates that the grass gynoecium is pseudomonomerous. It is problematic to interpret the gynoecium of grasses in terms of normal angiosperm gynoecium typology. Even the concept of carpel becomes misleading in grasses; instead, we recommend the term pistil for descriptive purposes.
... Collectively these four inflorescence types are referred to as monochasia (Eichler, 1879). While, it may have been possible that the lateral cymes in the Tacca chantrieri inflorescence were ancestrally derived from a bostryces which transitioned to a cincinni through a rhapidum or drapanium, as have been described in the Amaryllidaceae genera Clivia and Lapideria (Müller-Doblies and Müller-Doblies, 1978), it is more likely that the ancestor condition was a thyrsoid with uncondensed internodes; a common condition in this order (Remizowa et al., 2010;Nuraliev et al., 2021;Yudina et al., 2022). As such, the this represents a convergent case of an umbellate inflorescence since the lateral cymes are arrange differently than the bostryx derived umbellate taxa. ...
Inflorescence structure is very diverse and homoplasious, yet the developmental basis of their homoplasy is poorly understood. To gain an understanding of the degree of homology that these diverse structures share, we characterize the developmental morphology and anatomy of various umbellate inflorescences across the monocots and analyzed them in an evolutionary context. To characterize branching order, we characterized the developmental morphology of multiple inflorescences with epi-illumination, and vascular anatomy with Laser Ablation Tomography, a novel high-throughput method to reconstruct three-dimensional vasculature. We used these approaches to analyze the umbellate inflorescences in five instances of presumed homoplasy: in three members of the Amaryllidaceae; in three members of the Asparagaceae, including a putatively derived raceme in Dichelostemma congestum; in Butomus umbellatus (Alismataceae), in Tacca chantrieri (Dioscoreaceae), and in umbellate structure in Fritillaria imperialis (Liliaceae). We compare these with racemes found in three members of the subfamily Scilliioideae (Asparagaceae). We find there are three convergent developmental programs that generate umbellate inflorescences in the monocots, bostryx-derived, cincinnus-derived and raceme-derived. Additionally, among the bostryx-derived umbellate inflorescence, there are three instances of parallel evolution found in the Amaryllidaceae, in two members of Brodiaeoideae (Asparagaceae), and Butomus umbellatus, all of which share the same generative developmental program. We discuss the morphological modifications necessary to generate such complex and condensed structures and use these insights to describe a new variant of metatopy, termed horizontal concaulesence. We contextualize our findings within the broader literature of monocot inflorescence development, with a focus on synthesizing descriptive developmental morphological studies.
... In species with thyrses, the position of the floral prophyll is more precise. In Dioscorea L. (Dioscoreaceae), the female flowers are often in spikes and the male flowers are arranged in thyrses (Remizowa et al., 2010a). The branched male inflorescences of Dioscorea demonstrate alternation of right and left floral prophylls, which results in development of cincinni. ...
Species of the genus Burmannia possess distinctive and highly elaborated flowers with prominent floral tubes that often bear large longitudinal wings. Complicated floral structure of Burmannia hampers understanding its floral evolutionary morphology and biology of the genus. In addition, information on structural features believed to be taxonomically important is lacking for some species. Here we provide an investigation of flowers and inflorescences of Burmannia based on a comprehensive sampling that included eight species with various lifestyles (autotrophic, partially mycoheterotrophic and mycoheterotrophic). We describe the diversity of inflorescence architecture in the genus: a basic (most likely, ancestral) inflorescence type is a thyrsoid comprising two cincinni, which is transformed into a botryoid in some species via reduction of the lateral cymes to single flowers. Burmannia oblonga differs from all the other studied species in having an adaxial (vs. transversal) floral prophyll. For the first time, we describe in detail early floral development in Burmannia. We report presence of the inner tepal lobes in B. oblonga, a species with reportedly absent inner tepals; the growth of the inner tepal lobes is arrested after the middle stage of floral development of this species, and therefore they are undetectable in a mature flower. Floral vasculature in Burmannia varies to reflect the variation of the size of the inner tepal lobes; in B. oblonga with the most reduced inner tepals their vascular supply is completely lost. The gynoecium consists of synascidiate, symplicate, and asymplicate zones. The symplicate zone is secondarily trilocular (except for its distal portion in some of the species) without visible traces of postgenital fusion, which prevented earlier researchers to correctly identify the zones within a definitive ovary. The placentas occupy the entire symplicate zone and a short distal portion of the synascidiate zone. Finally, we revealed an unexpected diversity of stamen-style interactions in Burmannia. In all species studied, the stamens are tightly arranged around the common style to occlude the flower entrance. However, in some species the stamens are free from the common style, whereas in the others the stamen connectives are postgenitally fused with the common style, which results in formation of a gynostegium.
... The occurrence of common petal-stamen primordia in other genera of Eriocaulaceae, e.g., Paepalanthus, is controversial [11,28]. Remarkably, in most other monocots possessing common primordia, these occur only for inner whorl perianth members and corresponding stamens, even when the two perianth whorls are similar to each other in anthetic flowers (e.g.,Veratrum, Liliales, [2]; Dioscorea, Dioscoreales, [64]) or rarely for all perianth members and stamens on their radii. Formation of two whorls of common tepal-stamen primordia is documented in Allium (Asparagales: [65,66], sometimes takes place in Tofieldia (Alismatales), where this condition is unstable within a species [67] and possibly occurs in Scheuchzeria, Alismatales [2,[68][69][70]. ...
Eriocaulaceae (Poales) differ from potentially related Xyridaceae in pattern of floral organ arrangement relative to subtending bract (with median sepal adaxial). Some Eriocaulaceae possess reduced and non-trimerous perianth, but developmental data are insufficient. We conducted a SEM investigation of flower development in three species of Eriocaulon to understand whether organ number and arrangement are stable in E. redactum, a species with a highly reduced calyx and reportedly missing corolla. Early flower development is similar in all three species. Male and female flowers are indistinguishable at early stages. Despite earlier reports, both floral types uniformly possess three congenitally united sepals and three petals in E. redactum. Petals and inner stamens develop from common primordia. We assume that scanning electron microscopy should be used in taxonomic accounts of Eriocaulon to assess organ number and arrangement. Two types of corolla reduction are found in Eriocaulaceae: suppression and complete loss of petals. Common petal-stamen primordia in Eriocaulon do not co-occur with delayed receptacle expansion as in other monocots but are associated with retarded petal growth. The 'reverse' flower orientation of Eriocaulon is probably due to strictly transversal lateral sepals. Gynoecium development indicates similarities of Eriocaulaceae with restiids and graminids rather than with Xyridaceae.
... Patterns differ among various cases of stabilized anodic/cathodic asymmetry in angiosperms (Korn, 2006). For example, in inflorescence (thyrse) of Dioscorea tokoro, the bracteole of the first flower of a cincinnus always lies on the cathodic side of the axil of its subtending leaf, FIGURE 15 | Flower of Nuphar pumila whose diagram is provided in Figure 10D so the pattern is reverse to what is observed in Nuphar (Remizowa et al., 2010a). ...
European species of Nuphar are amongthe most accessible members of the basal angiosperm grade, but detailed studies using scanning electron microscopy are lacking. We provide such data and discuss them in the evolutionary context. Dorsiventral monopodial rhizomes of Nuphar bear foliage leaves and non-axillary reproductive units (RUs) arranged in a Fibonacci spiral. The direction of the phyllotaxis spiral is established in seedlings apparently environmentally and maintained through all rhizome branching events. The RUs can be located on dorsal, ventral or lateral side of the rhizome. There is no seasonality in timing of their initiation. The RUs usually form pairs in positions N and N + 2 along the ontogenetic spiral. New rhizomes appear on lateral sides of the mother rhizome. A lateral rhizome is subtended by a foliage leaf (N) and is accompanied by a RU in the position N + 2. We hypothesize a two-step process of regulation of RU/branch initiation, with the second step possibly involving environmental factors such as gravitropism. Each RU has a short stalk, 1-2 scale-like phyllomes and a long-pedicellate flower. We support a theory that the flower is lateral to the RU axis. The five sepals initiate successively and form two whorls as 3 + 2. The sepal arrangement is not ‘intermediate’ between whorled and spiral. Mechanisms of phyllotaxis establishment differ between flowers and lateral rhizomes. Petal, stamen and carpel numbers are not precisely fixed. Petals are smaller than sepals and form a whorl. They appear first in the sectors of the outer whorl sepals. The stamen arrangement is whorled to chaotic. The merism of the androecium tends to be the same as in the corolla. Flowers with odd numbers of stamen orthostichies are found. These are interpreted as having a non-integer merism of the androecium (e.g., 14.5). Carpels form a whorl in N. lutea and normally alternate with inner whorl stamens. Sterile second whorl carpel(s) are found in some flowers of N. pumila.
... Chirality of different structures can be order-dependent. For example, handedness of lateral cincinni (a class of inflorescence) appeared correlated with chirality of the inflorescence axis in Dioscorea tokoro Makino (Dioscoreaceae) (Remizowa et al., 2010). Similarly, asymmetric features of the leaf are dependent on its position in the leaf spiral, that is, whether a certain side of the leaf lamina faces the next or previous leaf primordium (Troll, 1935;cited from Meyen, 1973). ...
... It seems that the presence of common primordia of inner tepals and inner stamens is intimately linked in monocots with delayed receptacle expansion and delayed carpel initiation. In taxa with delayed receptacle expansion, initiation of (inner) tepals and stamens takes place in very rapid sequence, or almost simultaneously, leading to the appearance of common tepalstamen primordia (Remizowa et al. 2010a). The appearance of common petal-stamen primordia found in various eudicot families could be interpreted in terms of a gradual regression of the petals linked to their retardation in inception and slower growth (Ronse De Craene and Smets 1993). ...
Fusion between floral organs or their parts is believed to have played key roles in the origin and subsequent diversification of angiosperms. Two types of fusion can be recognized: postgenital and congenital. Postgenital fusion is readily observable during flower development: primary morphological surfaces of contacting structures meet and join during this process. After perfect postgenital fusion, no trace of the original epidermal layers can be recognized, but these remain visible, often in modified form, after imperfect postgenital fusion. Congenital fusion cannot be directly observed and takes place due to differential growth. In the case of complete congenital fusion, free parts of fused organs cannot be seen at any developmental stages. Incomplete congenital fusion implies the presence of free organ parts on the common (united) base; it can be divided into early and late congenital fusion depending on whether the common base precedes or follows the initiation of free parts during development. Phenomena related to congenital fusion are the development of free organs from common primordia, hybridization of developmental pathways, loss of organ individuality, heterotopies and fasciation. Differences between congenital and postgenital fusion are much more unequivocal than those between the presence and absence of fusion. There is no abrupt boundary between imperfect postgenital fusion and transient contact between organs during development. Structures assumed to be congenitally fused clearly develop as a unit, but it is necessary to demonstrate that these structures indeed belong to different merged organs (instead of being parts of the same organ or two distinct organs on a common base). This only can be done in the framework of comparative morphology. Analyses of both types of fusion involve arbitrary decisions, so it is not appropriate to discard the existence of any type. Conventional interpretations of morphological concepts lie at the base of analyses of character evolution, even if they are performed using maximum parsimony or model based methods and molecular phylogenetic data. Patterns of organ fusion are discussed here using three case studies.
... axis (Korn, 2006). For example, the handedness of all lateral cincinni in a given thyrse is precisely fixed in Dioscorea tokoro Makino (Dioscoreaceae), but varies among different thyrses of a given plant (Remizowa, Sokoloff & Kondo, 2010). There are apparently no records of the influence of anodic/cathodic asymmetry onto the arrangement of flowers with a left-and rightcontort corolla. ...
Transitions in corolla symmetry are an important aspect of angiosperm floral evolution. Contort petal aestivation is common in several groups of eudicots. In rosids, the direction of overlap between adjacent petals (handedness) of the contort corolla is often labile among flowers in a single inflorescence, but in asterids, handedness is usually stable at a supraspecific level. Taxa with contort corolla are unevenly distributed among asterids, and detailed developmental data are often lacking. We provide the first developmental study of flowers in Melanophylla (Torricelliaceae, Apiales), the only known campanulid with a contort corolla, and demonstrate that the corolla handedness is labile within a single inflorescence. Labile handedness distinguishes Melanophylla from members of lamiids with a contort corolla where handedness is stable. In Melanophylla, the handedness is determined by the arrangement of bracteoles. Petals are asymmetric from early developmental stages. The androecium is also usually contort, with handedness always opposite to that of the corolla. Anthers have broad, flat connectives, which is unusual in asterids. The gynoecium is pseudomonomerous, with the fertile carpel in a left or right-transversal position, depending on the handedness of the corolla and androecium. Symmetry patterns of all floral whorls, including the pseudomonomerous gynoecium, are strongly correlated in Melanophylla, in contrast with the unstable carpel orientation in monomerous gynoecia of Apiales studied so far. The tricarpellate pseudomonomerous gynoecia of Melanophylla and other early divergent Apiales resemble those of Dipsacales.
