Epigynous Flowers Research Articles

Peliosanthes epigynica (Asparagaceae, Convallarioideae), a new species from southeastern Vietnam

Peliosanthes epigynica, a new species occurring in a dry coastal forest in southeastern Vietnam (Ninh Thuan Province) is described and illustrated. It is distinguishable from any other Peliosanthes by a combination of the following character states: comparatively small elliptic leaf blades, drooping narrowly campanulate purple/violet flowers, and a nearly flat-topped, perfectly inferior ovary with a short straight (non-tortuous) conoid style. Besides data on morphological and ecological aspects, we provide notes on its taxonomic relationships to some other species similarly sharing completely epigynous flowers.

Homologies of Floral Structures in Velloziaceae with Particular Reference to the Corona

New data on floral morphology, development, and vasculature in two Brazilian genera of the monocot family Velloziaceae (Pandanales) are used to explore the homologies of their unusual floral structures, especially the corona of Barbacenia and the corona‐like appendages and multiple stamens of some Vellozia species. All Velloziaceae have epigynous flowers. Some species of Vellozia are polyandrous, and stamen number can be variable within species. In Vellozia jolyi, there is a single stamen opposite each sepal and a stamen fascicle (of three secondary stamens) opposite each petal. Each stamen possesses a single vascular bundle, and these are united into a single aggregate bundle in proximal regions of the fascicle. Stamens mature centripetally within each fascicle. The coronal appendages of both genera are closely associated with the stamens, but they share some vasculature with the tepals and develop late in ontogeny. The coronal organs cannot readily be homologized with any of the typical floral organs, but they show partial homology with both tepals and stamens. They are most readily interpreted as a late elaboration of the region between the petals and stamens associated with epigyny and the hypanthium.

Fleshy Fruits in Liliflorous Monocots

Fleshy fruits occur in several monocot orders and families, and it is generally assumed that they have been derived from capsular fruits many times during the of monocot lineages. Huber hypothesized in 1969 that most capsules in Asparagales are derived secondarily from berries and that this transformation was correlated with the of phytomelan-coated seeds, a pivotal character in his circumscription of Asparagales as part of reclassifying Liliaceae s.l. Dahlgren and co-workers suggested several parallel derivations and reversals in this character, e.g., the transformation sequence trifollicular fruits → capsules → berries → capsules → berries. Mapping of fleshy fruits on a phylogeny based on molecular characters indicates that Asparagales do not have fleshy fruits as a basal character. Dahlgren's cyclic character evolution hypothesis is not supported by the distribution of dry and fleshy fruits, and there is no obvious correlation between baccate fruits and phytomelaniferous seeds in Asparagales. Phytomelaniferous seeds are not an evident synapomorphy of Asparagales as presently circumscribed. The anatomy and development of different capsular and baccate fruits in selected genera are studied in an ongoing project to reveal homologies and establish an adequate fruit typology. Some observations of texture and dehiscence structures in dry and fleshy capsules and in typical berries from hypogynous and epigynous flowers are reported in this paper.

Morphology, inheritance and mapping of a compressed lamina mutant of carrot

AbstractA compressed lamina mutant at a locus named COLA was selected in an inbred population of the cultivated carrot Daucus carota sativus Hoffm. Whereas segregation analyses of F2 progenies, as well as corresponding F3 families, indicated a monogenic recessive inheritance, detailed morphological and histological analyses revealed pleiotropic effects of the COLA gene. The mutant plants exhibited a semi‐dwarf phenotype, shortened epidermal and leaf parenchyma cells and significantly reduced lamina dimensions. Furthermore, the mutant developed stipules and hypogynous flowers, contrary to the stipule‐less leaves and epigynous flowers of the wild type. Using bulked segregant analyses, thirty‐nine marker candidates were detected using 180 RAPD primer and 56 AFLP primer pairs. Twelve primers were linked to the COLA locus and mapped in a linkage group with a total length of 44.2 cM. Potential application of the compressed lamina mutant in carrot research is discussed.

Ovary Position Diversity in Saxifragaceae: Clarifying the Homology of Epigyny

We discuss the structural homology of the gynoecium and the developmental variations associated with ovary diversity in Saxifragaceae. Diverse ovary positions are present within most of the major clades in the family. We demonstrate that superior ovaries, although widely reported for various members of the family, are unusual and limited to a few species of Micranthes and Saxifraga and to male flowers of the dioecious Tanakaea among investigated genera. Most species reported to have superior ovaries actually have developmentally epigynous flowers in which the ovary has a small portion below the insertion of the perianth and androecium. Such ovaries of epigynous flowers that mimic superior ovaries are termed “pseudosuperior.” Labile shifts in proportioned growth of that part of the ovary above the insertion of the perianth and androecium to that below their insertion have created extensive variation in ovary position among closely related taxa, e.g., in both Saxifraga and Micranthes. The heterostylous Jepsonia has differences in ovary position among the different style‐length morphs, and similar variation in ovary position may be present in the dioecious Tanakaea. Epigynous flowers of Saxifragaceae fit the model of appendicular epigyny. During the organogenetic phase of early floral development, they exhibit peripheral upgrowth of the apical region, which forms a central concavity. The initial gynoecial primordium forms on the inner slope of the concavity, zonal growth in the concave flank subjacent to the initial gynoecial primordium elongates, and subsequently, the tissue lining the concave flank below the initial gynoecial primordium differentiates as ovary.

A phylogenetic analysis of 100+ genera and 50+ families of euasterids based on morphological and molecular data with notes on possible higher level morphological synapomorphies

A data matrix of 143 morphological and chemical characters for 142 genera of euasterids according to the APG system was compiled and complemented with rbcL and ndhF sequences for most of the genera. The data were subjected to parsimony analysis and support was assessed by bootstrapping. Strict consensus trees from analyses of morphology alone and morphology + rbcL + ndhF are presented. The morphological data recover several groups supported by molecular data but at the level of orders and above relationships are only superficially in agreement with molecular studies. The analyses provide support for monophyly of Gentianales, Aquifoliales, Apiales, Asterales, and Dipsacales. All data indicate that Adoxaceae are closely related to Dipsacales and hence they should be included in that order. The trees were used to assess some possible morphological synapomorphies for euasterids I and II and for the orders of the APG system. Euasterids I are generally characterised by opposite leaves, entire leaf margins, hypogynous flowers, “early sympetaly” with a ring-shaped corolla primordium, fusion of stamen filaments with the corolla tube, and capsular fruits. Euasterids II often have alternate leaves, serrate-dentate leaf margins, epigynous flowers, “late sympetaly” with distinct petal primordia, free stamen filaments, and indehiscent fruits. It is unclear which of these characters represent synapomorphies and symplesiomorphies for the two groups, respectively, and there are numerous expections to be interpreted as reversals and parallelisms.

Structural homology and developmental transformations associated with ovary diversification in Lithophragma (Saxifragaceae)

Lithophragma, comprising only ten species, encompasses a remarkable diversity of ovary positions, reported to range from inferior to superior. The structural homology of the gynoecium and developmental transformations associated with ovary diversification are investigated for Lithophragma. Scanning electron and light microscopy indicate that all species of Lithophragma have epigynous flowers. Lithophragma campanulatum, L. glabrum, and L. heterophyllum have ovaries that externally appear nearly superior, but are actually shallowly inferior or "pseudosuperior." The inferior ovaries of Lithophragma species can be conceptually divided into superior and inferior regions that meet at the point of perianth and androecial insertion. Static and ontogenetic allometry reveal that across the species of Lithophragma the lengths of these two ovary regions are coordinated. Ovary regions in mature flowers display an approximately linear relationship that can be expressed through the allometric equation SL = -0.5314 IL + 2.0348 (where SL and IL are the lengths of the superior and inferior regions of the ovary, respectively; r = 0.7683, df = 35, P = 2.45 × 10). Mapping ontogenetic allometries onto a recent phylogeny for Lithophragma shows that ovary position evolution is bidirectional and has shifted toward greater superiority in some species and greater inferiority in others.

Evolution of the Australasian Families Alseuosmiaceae, Argophyllaceae, and Phellinaceae

Based on results from cladistic analyses of morphology and DNA sequences (the two chlo- roplast genes rbcL and ndhF), the three Australasian families Alseuosmiaceae, Argophyllaceae, and Phelli- naceae are each monophyletic, belong within Asterales, and together form a monophyletic group. Two new rbcL sequences and thirteen new ndhF sequences were obtained. Congruence tests did not reveal any signif- icant incongruence between the two molecular data sets or between the molecular and morphological data. The character evolution of the Alseuosmiaceae-Argophyllaceae-Phellinaceae group is discussed. The Austra- lasian ancestor of this group was probably a woody plant with simple, alternate, serrate leaves and regular, choripetalous, epigynous flowers borne in panicles. All three families should be retained in line with the principle of ease of identification.

Nuclear Ribosomal RNA Sequences for Inferring Tribal Relationships Within Onagraceae

Relationships among tribes within the evening-primrose family, Onagraceae, were inferred from 18S and 26S ribosomal RNA sequences. Of 1819 nucleotide positions sequenced, 17 were phylogenetically informative. With Lythrum (Lythraceae) as the outgroup, one most parsimonious cladogram was derived (length = 28; consistency index = 0.75) using computer-assisted phylogeny inference software. The cladogram supported Ludwigia as the sister group to Onagraceae and provided strong evidence for the monophyly of Oenothera-Epilobium and Circaea-Fuchsia. The placements of Hauya and Lopezia were not well supported by the data as indicated by examining trees which were one step longer than the most parsimonious tree. Onagraceae is the best known and most thoroughly studied family in the order Myrtales (Raven 1989) and has been of evolutionary and genetic interest since deVries' classic analyses of non-Mendelian inheritance in mutants of Oenothera in 1886 (Cleland 1972). It is distinct from the other families in Myrtales by virtue of the following synapomorphic character-states: epigynous flowers (Eyde 1981), pollen with viscin threads (Skvarla et al. 1978), paracrystalline beaded ektexine (Skvarla et al. 1978), 4-nucleate embryo-sac formation (Raven 1979; Tobe and Raven 1983), vegetative tissues abundant with calcium oxalate raphides (Metcalfe and Chalk 1950; Carlquist 1975) and divided sporogenous (anther) tissue (Tobe and Raven 1986). The family consists of seven tribes, 16 genera and approximately 650 species (Raven 1989). Detailed information is available for much of this family for floral and vegetative anatomy and morphology (Carlquist 1977; Eyde 1982), breeding systems and pollinators (Raven 1979), embryology (Tobe and Raven 1983), pollen morphology (Patel et al. 1984), flavonoids (Averett and Raven 1984), and chromosome features (Kurabayashi et al. 1962). Although Onagraceae is well-characterized at many levels, tribal concepts and relationships within the family remain uncertain. The genera within Onagraceae are highly distinctive, suggesting that the lineages within the family diverged very early in its history (Raven 1989). If this is true, it is not surprising that evolutionary connections between tribes have proved difficult to resolve. Current classification places Ludwigia (tribe Jussiaeeae) as the sister group to all other Onagraceae, based on evidence from floral anatomy (Eyde 1977, 1979, 1981, 1982), cytology (Raven and Tai 1979) and amino acid sequence differences for the N-terminal region of the small subunit of ribulose bisphosphate carboxylase (RuBisCo; Martin and Dowd 1986). Fuchsieae, Circaeeae, Lopezieae, and Hauyeae are considered to be closely related because they are the least specialized members of the family with respect to floral and vegetative anatomy and chromosome number (Dahlgren and Thorne 1984; Raven 1989). At one time, Hauya was considered to be the basal genus of Onagreae (Tobe and Raven 1985; Raven 1989) based on similarities of pollen (Skvarla et al. 1975), chromosomes (Kurabayashi et al. 1962) and floral morphology (Raven 1979). It currently is placed in a separate tribe (Hauyeae) because the genera possess a number of features, such as presence of stipules, lack of interxylary phloem and a generalized leaf anatomy (Tobe and Raven 1985, 1986), that distinguish them from members of Onagreae. Tobe and Raven (1986) suggest a possible relationship between Onagreae (Clarkia) and Epilobieae, because both are highly specialized groups having unique four-lobed stigmas with the lobes in commissural position and dry, papillate stigma surfaces (Raven 1979; Eyde 1982). Along with Lopezia, they are the only groups in Onagraceae to display marked protandry (Raven 1979). In this study, nuclear ribosomal RNA (rRNA)

Floral anatomy of some Melastomataceae

AbstractThe floral anatomy of five taxa of Melastomataceae, namely, Memecylon edule, M. guinensis, M. capitellatum, Rhexia marina and Tabouchina semidecandra has been studied. The regular, epigynous flowers are tetramerous in Memecylon edule, M. capitellatum, Rhexia marina and pentamerous in M. guinensis and Tabouchina semidecandra. The floral parts as well as their traces show varying degrees of adnation. The septate condition of the ovary in Rhexia marina and Tabouchina semidecandra and the presence of rudimentary septa in Memecylon edule, M. guinensis and M. capitellatum reveal that the central placentation in the family is derived from axile or anatomically parietal ancestry. The carpels are 3‐traced in Memecylon edule, M. guinensis and M. capitellatum and 5‐traced in the rest. The style is vascularized by the dorsal bundles in Memecylon species and by the common median laterals in Rhexia marina and Tabouchina semidecandra.

Contributions to the floral morphology and embryology of Pavetta gardeniifolia A. Rich. Part 1. The inflorescence and flower

The inflorescence of Pavetta gardeniifolia is a thyrse. The entire inflorescence as well as each unit develops in stipular cavities lined by dendroid colleters associated with leaf nodulating bacteria. Excepting the bicarpellate ovary, the epigynous flowers are tetramerous, gamopetalous with epipetalous stamens. The vascularization of the flower is discussed in detail.

Floral Anatomy in the Saxifragaceae Sensu Lato. III. Kirengeshomoideae, Hydrangeoideae, and Escallonioideae

The floral morphology and anatomy of the one species in the monotypic Kirengeshomoideae, eight species in the Hydrangeoideae, and six in the Escallonioideae are described and compared. Similarities in floral structure and vascularization between Kirengeshoma palmata and members of the Philadelpheae strongly support the placement of this genus in the same subfamily as the tribe—the Hydrangeoideae. While the anatomy and morphology of flowers in the Hydrangeoideae do not clearly exclude the subfamily from a family that also includes the Saxifragoideae, certain commonly appearing floral characteristics probably do. These include relatively extensive polyandry, the frequent occurrence of highly vascularized isomerous gynoecia, petals with lateral bundles originating from traces in the sepal planes, no suggestion of a floral cup continuing beyond the divergence of the floral organs from the carpel walls in epigynous flowers, and essentially no independence among carpels in the ovary region of the gynoecium. In addition, a fascicled stamen arrangement characterizes the polyandrous members (Philadelpheae mostly). Although floral anatomy of too few members of the Escallonioideae has been investigated, the floral characteristics of this subfamily appear to be very diverse and not particularly distinctive when compared with the Saxifragoideae. Some diagnostic trends may be recognized, however: Escallonioids generally have fewer ovules per carpel (except Escallonia), less commonly show independence between carpels, and have epidermal hairs that are quite different from the complex trichomes of the flowers in Saxifragoideae. In addition, the ventral carpel bundles in two species studied in the subfamily terminate at the top of the ovary and do not enter the style.

FLORAL ANATOMY IN THE SAXIFRAGACEAE SENSU LATO. III. KIRENGESHOMOIDEAE, HYDRANGEOIDEAE AND ESCALLONIOIDEAE

The floral morphology and anatomy of the one species in the monotypic Kirengeshomoideae, eight species in the Hydrangeoideae, and six in the Escallonioideae are described and compared. Similarities in floral structure and vascularization between Kirengeshoma palmata and members of the Philadelpheae strongly support the placement of this genus in the same subfamily as the tribe—the Hydrangeoideae. While the anatomy and morphology of flowers in the Hydrangeoideae do not clearly exclude the subfamily from a family that also includes the Saxifragoideae, certain commonly appearing floral characteristics probably do. These include relatively extensive polyandry, the frequent occurrence of highly vascularized isomerous gynoecia, petals with lateral bundles originating from traces in the sepal planes, no suggestion of a floral cup continuing beyond the divergence of the floral organs from the carpel walls in epigynous flowers, and essentially no independence among carpels in the ovary region of the gynoecium. In addition, a fascicled stamen arrangement characterizes the polyandrous members (Philadelpheae mostly). Although floral anatomy of too few members of the Escallonioideae has been investigated, the floral characteristics of this subfamily appear to be very diverse and not particularly distinctive when compared with the Saxifragoideae. Some diagnostic trends may be recognized, however: Escallonioids generally have fewer ovules per carpel (except Escallonia), less commonly show independence between carpels, and have epidermal hairs that are quite different from the complex trichomes of the flowers in Saxifragoideae. In addition, the ventral carpel bundles in two species studied in the subfamily terminate at the top of the ovary and do not enter the style.

Flower of Tetraplasandra gymnocarpa Hypogyny with Epigynous Ancestry

Comparative herbarium studies, floral anatomy, and distributional data show that Tetraplasandra gymnocarpa, an araliad with hypogynous flowers, evolved in Hawaii from ancestors with epigynous flowers. Suggested causes for this reversal of a well-known evolutionary trend are (i) isolation of the ancestors from flowereating predators and (ii) selection for increased outcrossing.

FLORAL MORPHOLOGY, ORGANOGENESIS AND INTERPRETATION OF THE INFERIOR OVARY IN DOWNINGIA BACIGALUPII

The inflorescence of Downingia bacigalupii (Campanulaceae; Lobelioideae) is an indeterminate spike. Axillary flowers have a long, linear, inferior ovary with parietal placentation, a pentamerous synsepalous calyx, zygomorphic sympetalous corolla, syngenesious stamens, and a bicarpellate, syncarpous gynoecium. On the basis of floral vascular anatomy the inferior ovary is interpreted as appendicular, representing adnation of outer floral whorls to the gynoecium. Floral ontogeny shows that sepals are initiated in an adaxial to abaxial sequence rather than the 2/5 phyllotaxis reported for other members of Lobelioideae. Growth of the common bases of sepal lobes forms a floral cup and initiation of the following floral whorls occurs along the inner margins of the cup. Continued basal growth of the cup‐shaped bud results in the formation of the elongated inferior ovary. Earlier evidence for the interpretation of a cup‐shaped receptacle during development of epigynous flowers is reexamined and it is concluded that the concave floral bud of D. bacigalupii can also be interpreted as common growth of connate floral whorls, supporting interpretations based on vascular anatomy. Comparison of floral development between Downingia bacigalupii and Pereskia aculeata (Cactaceae) reveals ontogenetic differences between flowers with appendicular and receptacular cups.

Floral Morphology, Organogenesis and Interpretation of the Inferior Ovary in Downingia Bacigalupii

The inflorescence of Downingia bacigalupii (Campanulaceae; Lobelioideae) is an indeterminate spike. Axillary flowers have a long, linear, inferior ovary with parietal placentation, a pentamerous synsepalous calyx, zygomorphic sympetalous corolla, syngenesious stamens, and a bicarpellate, syncarpous gynoecium. On the basis of floral vascular anatomy the inferior ovary is interpreted as appendicular, representing adnation of outer floral whorls to the gynoecium. Floral ontogeny shows that sepals are initiated in an adaxial to abaxial sequence rather than the 2/5 phyllotaxis reported for other members of Lobelioideae. Growth of the common bases of sepal lobes forms a floral cup and initiation of the following floral whorls occurs along the inner margins of the cup. Continued basal growth of the cup-shaped bud results in the formation of the elongated inferior ovary. Earlier evidence for the interpretation of a cup-shaped receptacle during development of epigynous flowers is reexamined and it is concluded that the concave floral bud of D. bacigalupii can also be interpreted as common growth of connate floral whorls, supporting interpretations based on vascular anatomy. Comparison of floral development between Downingia bacigalupii and Pereskia aculeata (Cactaceae) reveals ontogenetic differences between flowers with appendicular and receptacular cups.