The floral scales in Hellmuthia (Cyperaceae, Cyperoideae) and Paramapania (Cyperaceae, Mapanioideae): an ontogenetic study

BACKGROUND AND AIMS: In 1976 the monotypic genus Hellmuthia was placed in the Hypolytreae s.l., but was subsequently ascribed to the Mapanioideae, tribe Chrysitricheae, mainly because of the presence in Hellmuthia of two lateral, mapanioid-like floral scales with ciliated keels, the anatomy of the nutlet, the embryo and the inflorescence. Recently, based on cladistic analyses and supported by pollen ontogenetic evidence, Hellmuthia was transferred to a Cyperaceae, tribe Cypereae, clade mainly consisting of Ficinia and Isolepis. In this study, the floral ontogeny in Hellmuthia was investigated and compared with the floral ontogeny in Paramapania, with special attention for the floral scales. METHODS: Freshly collected inflorescences of Hellmuthia membranacea and Paramapania parvibractea were investigated using scanning electron and light microscopy. KEY RESULTS: In the conical 'spikelet' in Hellmuthia, proximal bracts occur, each axillating an axis with empty glume-like structures, or a reduced spikelet. Hence, it is a reduced partial inflorescence. In Hellmuthia, the stamen primordia originate before the primordia of the perianth-gynoecium appear. Moreover, a third adaxially positioned 'floral scale' was observed for the first time. The position and relative time of appearance of the floral scales in Hellmuthia are typical for perianth parts in Cyperoideae. The basal position of Hellmuthia within a clade of species with usually perianthless flowers, allows the presence of rudiments of a perianth in Hellmuthia to be interpreted as a primitive state. Development of the lateral 'scales' in Paramapania follows a different pattern. Therefore, it was decided that the lateral 'scales' in Paramapania are different from the lateral perianth parts in Hellmuthia. The pollen grains in Hellmuthia are cyperoid, with one polar and five lateral apertures, of which the membrane is covered with sexinous bodies. The pollen surface is granulate and perforate with microspines. CONCLUSIONS: The floral ontogeny in Hellmuthia occurs according to the general cyperoid pattern. The lateral scales in Hellmuthia are perianth parts, and they are not homologous to the lateral 'scales' in Paramapania.     

Typical cyperoid reproductive structures in Lipocarpha humboldtiana and Ascolepis brasiliensis (Cypereae – Cyperoideae – Cyperaceae): New evidence from a development perspective

Ascolepis and Lipocarpha, Cyperaceae, have highly reduced reproductive structures and hypogynous scales that are controversially appreciated. Because of this, flowers and spikelets and, thus, inflorescences have been interpreted in different ways, which, in turn, has led to placing the two genera in different tribes. Some authors interpret spikelets in Ascolepis and Lipocarpha as many-flowered and the so-called hypogynous scales as homologous to the lateral scales of Hypolytrum, or consider these scales comparable to a Scirpus bristle. However, many other authors consider spikelets in Lipocarpha and Ascolepis to be a result of a reductional process from a many-flowered cyperoid spikelet to a single-flowered spikelet, where the adaxial and abaxial hypogynous scales may be seen as the respective prophyll and glume of the reduced spikelets. The latest molecular phylogenies of Cyperaceae show both genera nested in the Cyperus clade, forming, in turn, a clade together with the rest of the Cypereae genera having single-flowered spikelets and hypogynous scales. Alternatively, based on this, the scales of uncertain homology that accompany the Ascolepis and Lipocarpha flower might be seen as special reproductive formations, representing a synapomorphy of such clade, instead of relicts of an ancestor with many-flowered spikelets. In view of this, freshly collected inflorescences of Lipocarpha humboldtiana Nees and Ascolepis brasiliensis (Kunth) Benth. ex C. B. Clarke were studied using light and scanning electron microscopy, with the aim of elucidating the nature of the controversially interpreted reproductive structures of these species from a development perspective. Results show that the “hypogynous scales” simply represent vestigial structures derived from the reduction of typical cyperoid spikelets, rather than a perianth part or specialized formations emerging as evolutionary novelties. Two scales are typically generated in both species, one being abaxial and the other adaxial, homologous to a glume and a prophyll, respectively, which contrasts with the eprophyllate condition so far attributed to Ascolepis. In both cases, the inflorescence is a spike of reduced spikelets, and the floral development in L. humboldtiana and in A. brasiliensis follows the general ontogenetic pattern observed in Cyperoideae. These characteristics support the inclusion of both genera in the Cypereae tribe.     

Floral development and evolution of capitulum structure in Anacyclus (Anthemideae,Asteraceae)

Background and Aims

Most of the diversity in the pseudanthia of Asteraceae is based on the differential symmetry and sexuality of its flowers. In Anacyclus, where there are (1) homogamous capitula, with bisexual, mainly actinomorphic and pentamerous flowers; and (2) heterogamous capitula, with peripheral zygomorphic, trimerous and long-/short-rayed female flowers, the floral ontogeny was investigated to infer their origin.

Methods

Floral morphology and ontogeny were studied using scanning electron microscope and light microscope techniques

Key Results

Disc flowers, subtended by paleae, initiate acropetally. Perianth and androecium initiation is unidirectional/simultaneous. Late zygomorphy occurs by enlargement of the adaxial perianth lobes. In contrast, ray flowers, subtended by involucral bracts, initiate after the proximal disc buds, breaking the inflorescence acropetal pattern. Early zygomorphy is manifested through the fusion of the lateral and abaxial perianth lobes and the arrest of the adaxials. We report atypical phenotypes with peripheral ‘trumpet’ flowers from natural populations. The peripheral ‘trumpet’ buds initiate after disc flowers, but maintain an actinomorphic perianth. All phenotypes are compared and interpreted in the context of alternative scenarios for the origin of the capitulum and the perianth identity.

Conclusions

Homogamous inflorescences display a uniform floral morphology and development, whereas the peripheral buds in heterogamous capitula display remarkable plasticity. Disc and ray flowers follow different floral developmental pathways. Peripheral zygomorphic flowers initiate after the proximal actinomorphic disc flowers, behaving as lateral independent units of the pseudanthial disc from inception. The perianth and the androecium are the most variable whorls across the different types of flowers, but their changes are not correlated. Lack of homology between hypanthial appendages and a calyx, and the perianth double-sided structure are discussed for Anacyclus together with potential causes of its ray flower plasticity.     

Floral ontogeny in Scirpus, Eriophorum and Dulichium (Cyperaceae), with special reference to the perianth

BACKGROUND AND AIMS: Based on molecular phylogenetic analysis, it has been suggested recently that the Cyperaceae comprises only two subfamilies: the Mapanioideae and the Cyperoideae. In most flowers of the Cyperoideae, the whorl of inner stamens is reduced, resulting in tetracyclic flowers. In the more primitive (scirpoid) genera within the Cyperoideae, the perianth consists of two polysymmetric whorls, whereas the perianth parts in the more derived genera have been subject to modifications and/or reduction. Comparative studies of the many silky hairs of Eriophorum and of the eight bristles of Dulichium have given rise to much discussion about their homology. METHODS: The spikelet and floral ontogeny in freshly collected inflorescences was investigated using scanning electron microscopy. KEY RESULTS: Complete floral ontogenies are presented for Scirpus sylvaticus L., Eriophorum latifolium Hoppe and Dulichium arundinaceum (L.) Britton, with special reference to the perianth. The results in S. sylvaticus confirm the trimerous monocot-like organization of the flower. It is used as a model for floral development in Cyperoideae. In the early developmental stages, the androecium of E. latifolium is surrounded by a massive perigonial primordium, from which the many hair-like bristles originate. Consequently, the stamens develop among the hair primordia, more or less simultaneously. The hairs are arranged in whorls, which develop centripetally. The development of the perianth in D. arundinaceum starts with the formation of three initial perianth primordia opposite the stamens. Subsequently, two more abaxial bristle primordia, alternating with the stamens, originate simultaneously with the appearance of three adaxial bristle primordia in the zone where an adaxial inner perianth primordium is expected. CONCLUSIONS: The floral development in E. latifolium and D. arundinaceum can be considered as variations upon the scirpoid floral ontogenetic theme.     

Adaptive radiation of the putrid perianth: Ferraria (Iridaceae: Irideae) and its unusual pollinators

Field studies of 13 of the estimated 17 species of the southern African geophytic genus Ferraria (Iridaceae: Iridoideae) identified four distinct pollination systems. Ferraria flowers are radially symmetric and cupped with a large, mostly pale or dull-colored perianth. Perigonal nectaries secrete hexose dominant (fructose and glucose) nectar. Most species are pollinated by Diptera of four families, apparently attracted by strong floral odors, mostly putrid or fermenting, but sometimes apparently sweet, and a large perianth mottled and edged with dark color. Concentrated sugary secretions are produced on the tepal claws that form a shallow floral cup. In contrast, flowers of F. ferrariola have a deep, narrow floral cup, a pale blue or yellow perianth, and a spicy scent and are pollinated by bees in the family Apidae, rewarded by nectar of moderate sugar concentration. Ferraria divaricata and F. variabilis have dull-colored, darkly speckled or streaked perianths and produce ample, highly dilute nectar pooled at the base of the floral cup and are pollinated by eumenid and masarine wasps (Vespidae). Lastly, F. uncinata has flowers with a narrow floral cup and dull violet tepals with brown margins. They are visited only by meloid and melyrid beetles. All pollen transfers from the anther of a Ferraria flower to an insect’s body are passive, regardless of pollinator. Pollen load analyses suggests that all pollinators show a high degree of faithfulness to Ferraria flowers.     

Isolepis namaquana (Cypereae, Cyperaceae), a new endemic species from the winter rainfall area of South Africa

A new species, Isolepis namaquana Muasya & J.Viljoen, is described and illustrated. It is known from two localities in Namaqualand: near Kamieskroon and at the foot of the Matsikammaberge, where it grows in ephemeral wetlands. The tufted annual species is diagnosed by floral and fruit characters including glume size, bifid stigma and colliculate nutlet surface ornamentation.     

Floral and inflorescence morphology and ontogeny in Beta vulgaris, with special emphasis on the ovary position

Background and Aims

In spite of recent phylogenetic analyses for the Chenopodiaceae–Amaranthaceae complex, some morphological characters are not unambiguously interpreted, which raises homology questions. Therefore, ontogenetic investigations, emphasizing on ‘bracteoles’ in Atripliceae and flowers in Chenopodioideae, were conducted. This first paper presents original ontogenetic observations in Beta vulgaris, which was chosen as a reference species for further comparative investigation because of its unclarified phylogenetic position and its flowers with a (semi-)inferior ovary, whereas all other Chenopodiaceae–Amaranthaceae have hypogynous flowers.

Methods

Inflorescences and flowers were examined using scanning electron microscopy and light microscopy.

Key Results

Floral development starts from an inflorescence unit primordium subtended by a lateral bract. This primordium develops into a determinate axis on which two opposite lateral flowers originate, each subtended by a bracteole. On a flower primordium, first five tepal primordia appear, followed by five opposite stamen primordia. Simultaneously, a convex floral apex appears, which differentiates into an annular ovary primordium with three stigma primordia, surrounding a central, single ovule. A floral tube, which raises the outer floral whorls, envelops the ovary, resulting in a semi-inferior ovary at mature stage. Similarly, a stamen tube is formed, raising the insertion points of the stamens, and forming a staminal ring, which does not contain stomata. During floral development, the calyces of the terminal flower and of one of the lateral flowers often fuse, forming a compound fruit structure.

Conclusions

In Beta vulgaris, the inflorescence is compound, consisting of an indeterminate main axis with many elementary dichasia as inflorescence units, of which the terminal flower and one lateral flower fuse at a later stage. Floral parts develop starting from the outer whorl towards the gynoecium. Because of the formation of an epigynous hypanthium, the ovary becomes semi-inferior in the course of floral development.Key words: Beta vulgaris, Chenopodiaceae, floral ontogeny, gynoecial development, epigynous hypanthium, semi-inferior ovary, inflorescence ontogeny, LM, SEM     

A phylloid ground state of reverted floral specimens of Psophocarpus tetragonolobus (L.) DC (Fabaceae): Cancelled floral meristem and continued floral organ identity

Recombinants of Psophocarpus tetragonolobus (L.) DC (Fabaceae), homozygous for a recessive allele of a master homeotic gene reverted from a normal photosynthetic, sexual reproductive nature to a vegetative, non-reproductive nature. This included transmutative transformation of floral meristems to a non-sexual phylloid floral ground state where the virescent organs maintained their identity but floral meristem identity was cancelled thus giving rise to a form of anachronic reversion. This was usually followed by a scenario of phyllotactic alterations involving the elongation of the floral axis which physically transformed flowers, in varying degrees of spatial permutations by the formation of ancestral floral structures, including gynophore and a pericladial stalk: a form of paleochronic reversion. Research verified that an allele of the master homeotic gene responsible for this phenomenon is a prerequisite to that scenario. Specific permutations are directly controlled by at least four additional homeotic genes recognized, defined and functionally characterized herein. Their qualitative functions (i.e. dominant or recessive) are responsible respectively for the carpel form, being either vascularized (VSCARP) or digonolobe (vscarp); the state of the gynophore being formed (GNF) or nascent (gnf); the state of the pericladial stalk being formed (PCL) or nascent (pcl) and the bracts position remaining parallel (BCT:PRL) at the calyx (or on the pericladial stalk) or being dislocated due to an interbractial stem formation between bracts (bct:prl). Results indicate that floral meristem identity once established can naturally be cancelled with little or no effect on floral organ identity.     

Biosystematic studies inErythronium (Liliaceae-Tulipeae)

The floral biology ofErythronium japonicum has been studied from two approaches: a reinvestigation of its floral morphology and a pollinator case history. The perianth, differentiated into a sepal and petal cycle, has a tubular, but free arrangement basally around a slightly stipitate ovary. The two cycles of stamens with dimorphic filaments are positioned by the differently lobed auricles of the mature sepals and petals. These auricles also form a trap-lid mechanism for the inverted nectary which also has passageways. The perianth parts are highly UV absorbant due to the presence of flavonoids. This pattern contrasts strikingly with the purple trident basal guide lines so prominent in the visible spectrum. The weakly protandrous flowers also have exserted styles, thus functioning to exclude its own pollen and insure outbreeding. These floral adaptations are related specifically to the pollination behavior ofXylocopa appendiculata, and in general to the floral evolution within the genusErythronium. This work was supported in part by the U.S.-Japan Cooperative Science Program Grant GF-41367 and Grant-in-Aid No. 934053 from the Ministry of Education, Japan.     

Phylogenetic position of Cyperus clandestinus (Cypereae,Cyperaceae) clarified by morphological and molecular evidence

Extreme morphological reduction and convergent evolution can obscure taxonomic relationships. This phenomenon is frequently encountered in Cyperaceae, where characters traditionally used to diagnose genera have been shown to have evolved independently multiple times. The Ethiopian high‐altitude perennial first described as Cyperus clandestinus was subsequently moved to Ficinia because it has spiral glume arrangement, unlike typical Cyperus species, which have distichous glume arrangement. However, this position has remained uncertain as no nutlets have previously been studied to establish the presence or absence of the gynophore – the synapomorphy for Ficinia. We resolve this 140‐year‐old puzzle by describing the morphology of the nutlet, which lacks a gynophore, and use DNA sequence data to resolve the taxon within Cyperus. Cyperus clandestinus was found to be closely related to Remirea maritima and Cyperus cyperoides in the C₄Cyperus clade, whose members predominantly have distichously arranged glumes. This provides further evidence for the unreliability of glume arrangement as a character to distinguish between members of the Cyperus and Ficinia clades, whereas gynophore presence is more congruent with molecular data.     

Floral development of Berberidopsis corallina: a crucial link in the evolution of flowers in the core Eudicots

BACKGROUND AND AIMS: On the basis of molecular evidence Berberidopsidaceae have been linked with Aextoxicaceae in an order Berberidopsidales at the base of the core Eudicots. The floral development of Berberidopsis is central to the understanding of the evolution of floral configurations at the transition of the basal Eudicots to the core Eudicots. It lies at the transition of trimerous or dimerous, simplified apetalous forms into pentamerous, petaliferous flowers. METHODS: The floral ontogeny of Berberidopsis was studied with a scanning electron microscope. KEY RESULTS: Flowers are grouped in terminal racemes with variable development. The relationship between the number of tepals, stamens and carpels is more or less fixed and floral initiation follows a strict 2/5 phyllotaxis. Two bracteoles, 12 tepals, eight stamens and three carpels are initiated in a regular sequence. The number of stamens can be increased by a doubling of stamen positions. CONCLUSIONS: The floral ontogeny of Berberidopsis provides support for the shift in floral bauplan from the basal Eudicots to the core Eudicots as a transition of a spiral flower with a 2/5 phyllotaxis to pentamerous flowers with two perianth whorls, two stamen whorls and a single carpel whorl. The differentiation of sepals and petals from bracteotepals is discussed and a comparison is made with other Eudicots with a similar configuration and development. Depending on the resolution of the relationships among the basalmost core Eudicots it is suggested that Berberidopsis either represents a critical stage in the evolution of pentamerous flowers of major clades of Eudicots, or has a floral prototype that may be at the base of evolution of flowers of other core Eudicots. The distribution of a floral Bauplan in other clades of Eudicots similar to Berberidopsidales is discussed.     

Floral anatomy of Bromeliaceae, with particular reference to the evolution of epigyny and septal nectaries in commelinid monocots

Floral anatomy is described in ten genera of Bromeliaceae, including three members of subfamily Bromelioideae, three Tillandsioideae, and four genera of the polyphyletic subfamily Pitcairnioideae (including Brocchinia, the putatively basal genus of Bromeliaceae). Bromeliaceae are probably unique in the order Poales in possessing septal nectaries and epigynous or semi-epigynous flowers. Evidence presented here from floral ontogeny, vasculature, and the relative positions of nectary and ovules indicates that there could have been one or more reversals to apparent hypogyny in Bromeliaceae, although this hypothesis requires a better-resolved phylogeny. Such evolutionary reversals probably evolved in response to specialist pollinators, and in conjunction with other aspects of floral morphology of Bromeliaceae, such as the petal appendages of some species. The ovary is initiated in an inferior position even in semi-epigynous or hypogynous species. The ovary of all so-called hypogynous Bromeliaceae is actually semi-inferior, because the septal nectary is infralocular; in these species the nectaries have a labyrinthine surface and many vascular bundles. Brocchinia differs from most other fully epigynous species in that each carpel is secretory at the apex and reproductive, rather than secretory, at the base.     

FLORAL DEVELOPMENT IN MYRISTICA (MYRISTICACEAE)

Myristica fragrans and M. malabarica are dioecious. Both staminate and pistillate plants produce axillary flowering structures. Each pistillate flower is solitary, borne terminally on a short, second-order shoot that bears a pair of ephemeral bracts. Each staminate inflorescence similarly produces a terminal flower and, usually, a third-order, racemose axis in the axil of each pair of bracts. Each flower on these indeterminate axes is in the axil of a bract. On the abaxial side immediately below the perianth, each flower has a bracteole, which is produced by the floral apex. Three tepal primordia are initiated on the margins of the floral apex in an acyclic pattern. Subsequent intercalary growth produces a perianth tube. Alternate with the tepals, three anther primordia arise on the margins of a broadened floral apex in an acyclic or helical pattern. Usually two more anther primordia arise adjacent to each of the first three primordia, producing a total of nine primordia. At this stage the floral apex begins to lose its meristematic appearance, but the residuum persists. Intercalary growth below the floral apex produces a columnar receptacle. The anther primordia remain adnate to the receptacle and grow longitudinally as the receptacle elongates. Each primordium develops into an anther with two pairs of septate, elongate microsporangia. In pistillate flowers, a carpel primordium encircles the floral apex eventually producing an ascidiate carpel with a cleft on the oblique apex and upper adaxial wall. The floral ontogeny supports the morphological interpretation of myristicaceous flowers as trimerous with either four-sporangiate anthers or monocarpellate pistils.     

The need to re-investigate the nature of homoplastic characters: an ontogenetic case study of the 'bracteoles' in Atripliceae (Chenopodiaceae)

Background and Aims

Within Chenopodioideae, Atripliceae have been distinguished by two bracteoles enveloping the female flowers/fruits, whereas in other tribes flowers are described as ebracteolate with persistent perianth. Molecular phylogenetic hypotheses suggest ‘bracteoles’ to be homoplastic. The origin of the bracteoles was explained by successive inflorescence reductions. Flower reduction was used to explain sex determination. Therefore, floral ontogeny was studied to evaluate the nature of the bracteoles and sex determination in Atripliceae.

Methods

Inflorescences of species of Atriplex, Chenopodium, Dysphania and Spinacia oleracea were investigated using light microscopy and scanning electron microscopy.

Key Results

The main axis of the inflorescence is indeterminate with elementary dichasia as lateral units. Flowers develop centripetally, with first the formation of a perianth primordium either from a ring primordium or from five individual tepal primordia fusing post-genitally. Subsequently, five stamen primordia originate, followed by the formation of an annular ovary primordium surrounding a central single ovule. Flowers are either initially hermaphroditic remaining bisexual and/or becoming functionally unisexual at later stages, or initially unisexual. In the studied species of Atriplex, female flowers are strictly female, except in A. hortensis. In Spinacia, female and male flowers are unisexual at all developmental stages. Female flowers of Atriplex and Spinacia are protected by two accrescent fused tepal lobes, whereas the other perianth members are absent.

Conclusions

In Atriplex and Spinacia modified structures around female flowers are not bracteoles, but two opposite accrescent tepal lobes, parts of a perianth persistent on the fruit. Flowers can achieve sexuality through many different combinations; they are initially hermaphroditic, subsequently developing into bisexual or functionally unisexual flowers, with the exception of Spinacia and strictly female flowers in Atriplex, which are unisexual from the earliest developmental stages. There may be a relationship between the formation of an annular perianth primordium and flexibility in floral sex determination.     

A Floral Ontogenetic Approach to Questions of Homology within the Cyperoideae (Cyperaceae)

Within the Cyperoideae, which comprise all Cyperaceae except the Mapanioideae, several questions of homology are discussed and reinterpreted based on results of our SEM and LM floral ontogenetic studies. In all species studied, spikelets are interpreted as being indeterminate, with spirally to distichously arranged glumes, each subtending (or not) a flower. Floral development starts with the formation of two lateral stamen primordia, simultaneously with, or followed by the formation of a third, abaxial stamen primordium. Perianth parts, if present, originate only after the formation of the androecium, simultaneously with the appearance of an annular ovary primordium, surrounding a central ovule primordium. Perianth parts vary in number and morphology, and, where present, perianth development follows a general pattern. Three (or two) stigma primordia are formed on the top of the rising ovary wall. In dimerous gynoecia, stigma primordia originate either dorsiventrally, resulting in a laterally flattened ovary/nutlet, or laterally, resulting in a dorsiventrally flattened ovary/nutlet. We conclude that in all species studied the spikelet and floral development occurs according to a general, scirpoid, ontogenetic pattern, which we illustrate using new spikelet and floral ontogenetic results in Eleocharis palustris and other species. Spikelet and floral ontogeny in species with apparently deviating morphologies, can be traced back to the general ontogenetic pattern.

---

Resumen  Varias preguntas sobre homología para las Cyperoideae, que incluyen todas las Cyperaceae excepto las Mapanioideae, se discuten e interpretan con base en estudios de ontogenia floral realizados con SEM y LM. En todas las especies estudiadas, las espiguillas son indeterminadas con glumas arregladas en espiral o dicotomicamente, cada una sosteniendo (o no) una flor. El desarrollo floral comienza con la formación de dos primordios estaminales laterales, simultáneamente con o seguido por la formación del tercer primordio estaminal abaxial. Si se desarrollan las partes del perianto, se originan solo después de la formación del androceo, simultáneamente con el desarrollo del primordio anular del ovario que envuelve al primordio central del óvulo. Cuando están presentes las partes del perianto, varían en número y morfología y el desarrollo sigue un patrón general. Se forman tres (o dos) primordios del estigma en el ápice de la pared del ovario en desarrollo. En gineceos dímeros, los primordios de los estigmas se originan dorsiventralmente resultando en una nuececilla/ovario comprimido lateralmente, o se originan lateralmente, resultando en una nuececilla/ovario comprimido dorsiventralmente. Concluimos que, tanto el desarrollo floral, como el de las espiguillas en todas las especies estudiadas, siguen un patrón ontogenético general scirpoide que se ilustra con los resultados obtenidos para Eleocharis palustris y otros especies. La ontogenia floral y de las espiguillas en especies con morfologías aparentemente atípicas, puede estar reducida al patrón ontogenetico general.

     

中国大陆天麻属一新分布种——细天麻

报道了中国大陆兰科(Orchidaceae)天麻属(Gastrodia)1新记录种——细天麻(Gastrodia gracilis Bl.)。标本采自云南省开远市碑格乡,生于海拔约2 500m的常绿阔叶林下,群落郁闭度较大,林下湿润。标本主要形态学特征为总状花序长约6cm,花排列稀疏,管状,下垂,浅棕色,花被筒顶端5裂,苞片宿存,地下茎小。该种此前记录产于中国台湾及日本。该发现在中国大陆尚属首次,加强了中国云南植物区系与中国台湾以及日本植物区系的联系。     

Normapolles plants: a prominent component of the Cretaceous rosid diversification

The Normapolles complex, characterised by its oblate and triaperturate pollen, constitutes an important and diverse element of many Late Cretaceous and Early Cainozoic floras of the Northern Hemisphere. Based on the dispersed pollen record alone it has been difficult to assess systematic affinities, but relationships with Fagales have been proposed. Over the past twenty years several exquisitely preserved Late Cretaceous reproductive structures with Normapolles type pollen in situ have been described. In this study we provide a summary and new information of these floral structures. Further, a new genus, Dahlgrenianthus, is described from the Late Cretaceous of southern Sweden. The genus includes the type species Dahlgrenianthus suecicus, a number of reproductive structures referred to Dahlgrenianthus sp., and Dahlgrenianthus trigonus (Knobloch et Mai) comb. nov. from the Maastrichtian flora of Walbeck, Germany. Dahlgrenianthus comprises small flowers with pentamerous perianth and androecium and a tricarpellate gynoecium. It is distinguished from all other Normapolles floral structures in its hypogynous floral organisation. All Normapolles floral structures described so far are thought to be related to various members of the core Fagales, but the group is obviously not monophyletic. The stratigraphic range of the Normapolles taxa and other fagalean fossils strongly suggests that all major fagalean lineages were present by the Cenomanian or earlier.     

Flower structure and development of Araceae compared with alismatids and Acoraceae

Floral development of Araceae is compared with that of other basal monocots such as alismatids and Acorus. Flowers of Araceae, Acorus and several alismatids with spicate inflorescences lack a subtending floral bract. In Araceae and some Potamogetonaceae the subtending floral bract is suppressed, and not incorporated into the perianth. This differs from Acorus and some alismatids, where a bract-like median abaxial tepal is formed in the outer perianth whorl (i.e. developmental merger of flower-subtending bract and tepal). In Araceae, Acorus and spicate alismatids flowers develop unidirectionally, correlated with bract reduction. Araceae lack unidirectionality in the outer perianth whorl, in contrast t o Acorus and Juncaginaceae. The transition from trimerous to dimerous flowers in Onintiurn (Araceae) is by accentuation of the unidirectionality of the inner perianth. The gynoecium of Araceae and Acorus is synascidiate. However, in most Araceae the synascidiate portion is shorter than in Acorns, and a distinct basal elongation phase as in Acorus and Juncaginaceae was not found. The perianth and androecium of Lysichiton and Symplocarpus and the gynoecium of Gymnostachys differ from other Araceae and resemble those in Potamogetonaceae. Developmental findings support the isolation of Acorus from Araceae, and show similarities of Araceae with Potamogetonaceae and of Acorus with Juncaginaceae.     

基部被子植物雪香兰（金粟兰科）单性花的形态发生和发育

基部被子植物金粟兰科（Chloranthaceae）的单性花或两性花结构十分简单,雪香兰（Hedyosmum orientale）花单性、雌雄异株,花的形态及结构与其它属物种具有显著的差异,对于研究被子植物花特别是花被的起源和系统进化具有重要意义。该研究采用电子显微镜和光学显微镜观察了雪香兰单性花的器官发生及发育过程。结果表明,雌、雄花均为顶生和腋生,多个小花呈聚伞圆锥状排列。雄花外侧是苞片,每朵雄花上着生150–200个雄蕊,花轴基部着生少数退化的叶原体。苞片原基及其腋生的花原基最初呈圆丘状,随后伸长。在雄花发育过程中,苞片原基比雄蕊原基生长快,雄花原基纵向伸长,叶原体原基在基部发生,雄蕊原基自下而上发生。每2朵雌花底部合生形成小聚伞花序,每朵雌花被一苞叶包裹,由单心皮和三棱型子房构成,外覆三裂叶状花被。在雌花发育过程中,雌花原基比苞片原基生长快,花被原基首先于花顶端发生,随后花顶端中心凹陷,进一步发育成具有单心皮的子房原基。雪香兰的单性花发育不经过两性同体阶段,花分生组织只起始雄蕊器官或雌蕊器官的发育。研究结果支持雪香兰单性花是原始性状的观点,雄花叶原体与雌花三裂叶状花被同源,可能是花被（萼片与花瓣）的起源。