Developmental morphology of the flower of <Emphasis Type="Italic">Dracontium polyphyllum</Emphasis> in the context of the phylogeny of the Araceae

The inflorescence of Dracontium polyphyllum consists of 150 – 300 flowers arranged in recognisable spirals. The flower has 5 – 6 (90% of observed specimens), or 7 broad tepals enclosing 9 – 12 stamens (occasionally 7) inserted in two whorls. The gynoecium is trilocular (90% of observed specimens) or tetralocular. The tetralocular gynoecia are found at random among the trilocular gynoecia. Each locule encloses an ovule inserted in an axile position, in the median portion of the ovary. Each carpel has its own stylar canal. However, in the upper portion of the style, there is only one common stylar canal. Floral organs are initiated in an acropetal direction in the following sequence: tepals, stamens, and carpels. During later stages of development, the tepals progressively cover the other floral organs. The first floral primordia are initiated on the upper portion of the inflorescence. During early stages of development, the floral primordia have a circular shape. The tepals are initiated nearly simultaneously. During later stages of development, the first whorl of stamens develops in alternation with the tepals and is followed by a second whorl of stamens. The trilocular or tetralocular nature of the ovary is clearly visible during early stages of development of the gynoecium. Recent molecular studies show that Anaphyllopsis A. Hay and Dracontium L. are closely related. However, although pentamerous flowers have been observed in Anaphyllopsis, the developmental morphology of the flower of Dracontium is different from that of Anaphyllopsis.     

海韭菜的花器官发生

运用扫描电镜（SEM）观察了海韭菜（Triglochin maritimum）的花器官发生发育过程。结果表明：海韭菜花发育是典型的单子叶植物发生模式,即两轮花被片、两轮雄蕊和两轮心皮以三基数轮状交替发生,花器官是以向心向顶的方式发生的,未发现“花被片—雄蕊复合原基”。 发育后期雄蕊和与之对生的花被片之间的共同基部可能是相继向上居间生长的结果。花被片轮和雄蕊轮二者之间在发育位置、时间和速率上存在差异,内轮花被片原基和外轮雄蕊原基的不同发育时间和发育速度使得在成熟花中内轮花被片位于外轮雄蕊的内方。观察结果不支持水麦冬属植物的花是退化（或压缩）的花序侧分枝等假花的观点。     

Floral development of Urospatha: merosity and phylogeny in the Lasioideae (Araceae)

In this paper we study merosity in the genus Urospatha within the framework of a resolved phylogeny of the Araceae. We analyse how a transition from dimerous or tetramerous merosity to pentamerous or hexamerous merosity can occur developmentally in the Lasioideae. In Urospatha, initiation of floral primordia along the inflorescence is acropetal, while development of flowers is basipetal. This indicates the presence of two distinct phases in the development of the Urospatha inflorescence. The first phase corresponds to initiation of flowers and establishment of the phyllotactic pattern, and the second phase to differentiation of floral organs. Urospatha is characterized by the presence of trimerous, tetramerous, pentamerous and rarely hexamerous flowers. In all types of flowers, the stamens are closely associated and opposite to the tepals. Pentamerous flowers are formed by addition of a sector comprising a stamen and tepal. Likewise, in the case of hexamerous flowers, two sectors are added. In the Lasioideae, the increase in the number of tepals and stamens is linked with two developmental processes that have appeared independently in the subfamily: (1) addition of one or two stamen?Cpetal sectors (Anaphyllopsis and Urospatha), and (2) independent increase in the number of tepals and stamens on whorls, more or less organized and inserted in alternate position (Dracontium). Tetramerous whorls as they occur in basal Lasioideae would be homologous to two dimerous whorls from an evolutionary point of view.     

RE-EVALUATION OF CERTAIN KEY RELATIONSHIPS IN THE ALISMATIDAE: FLORAL ORGANOGENESIS OF SCHEUCHZERIA PALUSTRIS (SCHEUCHZERIACEAE)

Transition to flowering in the North-temperate bog plant Scheuchzeria palustris occurs in early May and results in the formation of a simple raceme with six flowers. Five of the flowers are subtended by large foliar bracts, while the sixth and last-formed flower on the inflorescence remains ebracteate. The individual flowers develop along a clearly trimerous pattern. The three outer tepals develop first, arising almost simultaneously at the periphery of the triangular floral apex. They are followed closely by the development of the three anti-tepalous outer stamens. The three inner tepals are next in the developmental sequence, alternating with the outer whorl of tepal-stamen pairs but arising at a slightly higher level on the floral meristem. Three inner stamens are initiated opposite the inner tepal primordia. Finally, three gynoecial primordia are initiated on the remaining central portion of the floral apex and alternating with the inner whorl of tepal-stamen pairs. Each carpel develops at first as a horseshoe-shaped structure. Two ovules form in each carpel, initiating on the adaxial margin of the carpel wall. Histogenesis of all floral appendages involves initially periclinal divisions in the second tunica layer followed by corresponding anticlinal divisions in the first tunica layer and concurrent activity in the underlying corpus. Separate procambial strands differentiate acropetally from the inflorescence axis to each tepal-stamen pair and then bifurcate. The vascular connection to the gynoecium develops directly from the strands in the tepal-stamen pairs. The results of this developmental study of the flower of S. palustris have a significant bearing on the positioning of this and related taxa within the Alismatidae and on the speculation of the phylogeny of the monocotyledon flower.     

Comparative ontogeny of perfect and pistillate florets in Senecio vernalis (Asteraceae)

We studied the inflorescence, and in particular ontogeny and development of the florets in Senecio vernalis as a representative member of Asteraceae, using epi-illumination microscopy. Initiation and subsequent development of florets on the highly convex inflorescence apex occur acropetally, except for pistillate ray florets, which show a lag in initiation. Receptacular bracts derive from the receptacular surface after development of all florets. The order of whorl initiation in both disc and ray florets include corolla, androecium and finally the pappus, together with the gynoecium. Development of corolla lobes from a ring meristem occurs in bidirectional order starting from the lateral side, whereas stamens incept unidirectionally from the abaxial side. Concurrently with the inception of two median carpel primordia, a ring meristem develops at the base of the corolla from which pappus bristles differentiate in later stages. Pistillate ray florets show significant differences from perfect disc florets as reflected by the zygomorphic shape of the floral apex and a shift of floral merosity from pentamery to tetramery. Loss of stamens in ray florets occurs due to abortion of primordia after initiation.     

Inflorescence and floral development of Dahlstedtia species (Leguminosae: Papilionoideae: Millettieae)

Inflorescence and floral development of two tropical legume trees, Dahlstedtia pinnata and Dahlstedtia pentaphylla, occurring in the Atlantic Forest of south-eastern and southern Brazil, were investigated and compared with other papilionoids. Few studies have been made of floral development in tribe Millettieae, and this paper is intended to fill that gap in our knowledge. Dahlstedtia species have an unusual inflorescence type among legumes, the pseudoraceme, which comprises axillary units of three or more flowers, each with a subtending bract. Each flower exhibits a pair of opposite bracteoles. The order of flower initiation is acropetal; inception of the floral organs is as follows: sepals (5), petals (5), carpel (1) plus outer stamens (5) and finally inner stamens (5). Organ initiation in sepal, petal and inner stamen whorls is unidirectional; the carpel cleft is adaxial. The vexillum originates from a tubular-shaped primordium in mid-development and is larger than other petals at maturity, covering the keels. The filament tube develops later after initiation of inner-stamen primordia. Floral development in Dahlstedtia is almost always similar to other papilionoids, especially species of Phaseoleae and Sophoreae. But one important difference is the precocious ovule initiation (open carpel with ovules) in Dahlstedtia, the third citation of this phenomenon for papilionoids. No suppression, organ loss or anomalies occur in the order of primordia initiation or structure. Infra-generic differences in the first stages of ontogeny are rare; however, different species of Dahlstedtia are distinguished by the differing distribution pattern of secretory cavities in the flower.     

MADS-box gene expression and implications for developmental origins of the grass spikelet

Basic questions regarding the origin and evolution of grass (Poaceae) inflorescence morphology remain unresolved, including the developmental genetic basis for evolution of the highly derived outer spikelet organs. To evaluate homologies between the outer sterile organs of grass spikelets and inflorescence structures of nongrass monocot flowers, we describe expression patterns of APETALA1/FRUITFULL-like (AP1/FUL) and LEAFY HULL STERILE-like (LHS1) MADS-box genes in an early-diverging grass (Streptochaeta angustifolia) and a nongrass outgroup (Joinvillea ascendens). AP1/FUL-like genes are expressed only in floral organs of J. ascendens, supporting the hypothesis that they mark the floral boundary in nongrass monocots, and JaLHS1/OsMADS5 is expressed in the inner and outer tepals, stamen filaments and pistil. In S. angustifolia, SaFUL2 is expressed in all 11 (or 12) bracts of the primary inflorescence branch, but not in the suppressed floral bract below the abscission zone. In contrast, SaLHS1 is only expressed in bracts 6-11 (or 12). Together, these data are consistent with the hypotheses that (1) bracts 1-5 of S. angustifolia primary inflorescence branches and glumes of grass spikelets are homologous and that (2) the outer tepals of immediate grass relatives, bracts 6-8 of S. angustifolia, and the lemma/palea are homologous, although other explanations are possible.     

洋葱花器数目变异研究

以洋葱JQS-1、MST-140、Red beauty 3个常规栽培品种的鳞茎为试材,观察统计洋葱花器数目的变化,探讨花器数目的变异与植物花器多样性的关系,为植物花器发育模式以及植物分类和系统发育研究提供依据。结果表明:(1)洋葱花序中正常的洋葱小花含有6枚雄蕊,一些异常小花雄蕊的数目减少到5枚或增加到7~11枚;正常花药中的花粉粒数量大、形状规则、分散均匀,而异常花药中的花粉粒形状不规则。(2)雌蕊数目也发生变异,子房由正常的3室,变成了2室、4室或6室;花柱从正常1枚,增加到2枚或3枚。(3)正常小花含有6片花被片,异常小花的花被片数目从5片到10片。(4)花被片与雄蕊数目的变异有同步增减和非同步增加2种类型。     

Floral organogenesis of Potamogeton distinctus A. Benn. (Potamogetonaceae)

The floral organogenesis of Potamogeton distinctus A. Benn. was observed under the scanning electron microscope (SEM). The floral buds are first initiated on the lower portion of inflorescence in alternating whorls of three. Each of the floral buds is subtended by a bract primordium during the early stages. The primordia of the floral appendages arise on the floral bud acropetally. Two lateral tepals are first initiated and then two median ones soon after. Stamens are normally initiated as elongate primordia opposite the tepals, with the two lateral stamens preceding the median ones. The two carpel primordia arise alternating with the stamens. In some flowers, one of the two gynoecial primordia becomes inactive soon after they are initiated, or only one carpel primordium is initiated. The present observation of the gynoecial development supports the viewpoint that the evolution of flower in Potamogeton involves a reduction in number of parts. The existence of bract primordium during the early stages in many species of Potamogeton indicates that the absence of bractin mature flowers should be the result of reduction.     

风信子花器官中HAP2基因的分离与表达研究(英文)

在离体条件下,以风信子花被片为外植体,通过控制激素的浓度可诱导花被片、雄蕊或胚珠的再生。近年来,在拟南芥和金鱼草等模式植物中已经分离出了许多控制花器官发育的同源异形基因,如AG,AP1,AP2,AP3等,其中AP2在控制花萼和花瓣形成过程中起重要作用,因此本文从风信子中分离AP2的同源基因,并对它在风信子再生系统中的表达进行了分析。根据AP2同源基因功能域的保守序列设计一对简并引物：5'-TGGGA（A/G）TC（G/T/C）CA（C/T）AT（C/T）TGGA-3'和5'-TCCCA(AGC)(CT)(GT)(AG)CC(AG) CA(CT)TT(AG)TG-3', 以再生的花被片为材料进行RT-PCR,扩增出大小约300bp的片段,序列分析表明该片段的氨基酸序列与AP2同源性高达89%。进而,利用5’和3’Race PCR,得到全长的cDNA。该基因命名为HAP2,GenBank登记号为AF134116,该基因全长1597bp,编码368个氨基酸(Fig.1）。与AP2相比,HAP2也含有10个氨基酸长的碱性功能域,其中KKSR为核定位信号。此外,HAP2也含有两个序列重复的68个氨基酸长的功能域（HAP2-R1,HAP2-R2）,HAP2-R1也含有能形成(-螺旋结构的核心区域,且与AP2-R1中的核心序列100%同源,而HAP2-R2中的核心区域与AP2-R2相比, 缺少9个氨基酸(Fig.2）。RT-PCR结合Southern 杂交结果表明(Fig.3）,HAP     

Comparative floral ontogenies among Persoonioideae including Bellendena (Proteaceae)

Floral ontogeny is described and compared in five species and four genera of the hypothetically basal proteaceous subfamily Persoonioideae sensu Johnson and Briggs. The hypotheses surrounding the origin of the peculiar proteaceous flower and homologous structures within the flowers are examined using ontogenetic morphological techniques. Ontogenetic evidence reveals that the proteaceous flower is simple, composed of four tepals, each tepal initiated successively with the lateral tepals being initiated first and second followed by the successive initiation of the sagittal tepals. Each of four stamens is initiated opposite a tepal in a similar sequence to tepal initiation. A single carpel develops terminally from the remaining floral meristem. In taxa of Persoonieae, nectaries are initiated from a broadened receptacle in alternistamenous sites after zonal growth beneath and between the tepals and stamens has begun. The nectaries are interpreted as secondary organs, not reduced homologues of a “lost” petal or stamen series. Developmental variation is present among the examined taxa in several forms including the development of a Vorlaüferspitze (spine) on the upper portion of the tepals, adnation between the anthers and tepals, and formation of the carpel. In Placospermum the early formation of the carpel cleft extends to the floral receptacle and in the other taxa, the carpel cleft is distinctly above the receptacle. Different developmental pathways result in similar mature morphologies of the carpel in Persoonia falcata and Placospermum coriaceum. Bellendena montana is unique relative to the other taxa in having free stamens, a punctate stigma, reduced (not lost) floral bracts, and the floral and bract primordia are initiated from a common meristem. This study provides a foundation for future studies of the developmental basis of floral diversity within Proteaceae.     

Floral developmental morphology of three Indigofera species (Leguminosae) and its systematic significance within Papilionoideae

Inflorescence and floral development of three species of Indigofera (Leguminosae-Papilionoideae), I. lespedezioides, I. spicata, and I. suffruticosa, were investigated and compared with that of other papilionoid groups, especially with members of the recently circumscribed Millettioid clade, which was merged as sister to Indigofereae in a recent cladistic analysis. Although Indigofera is a genus of special interest, because of its great richness in species and its economic importance, few studies have been made of floral development in the genus or in Indigofereae as a whole. Flower buds and inflorescences were analysed at several stages of development in the three species. Our results confirmed that Indigofera species bear a usual inflorescence type among legumes, the raceme, which comprises flowers initiated in acropetal succession, each with a subtending bract and no bracteoles initiated. The inception of the floral organs is as follows: sepals (5), petals (5), carpel (1), outer stamens (5), and, finally, inner stamens (5). Organ initiation in the sepal, petal, and both stamen whorls is unidirectional, from the abaxial side; the carpel cleft is adaxial. The vexillum is larger than other petals at maturity, covering the keels, which are fused edge-to-edge. Nine filaments are fused to form an adaxially open sheath, and the adaxial stamen of the inner whorl remains free (diadelphous androecium) in the mid-stage of development. Most of the infra-generic differences occurred in the later stages of development. Data on floral development in Indigofera obtained here were also compared with those from other members of Papilionoideae. This comparison showed that the early expression of zygomorphy is shared with other members of the Millettioid clade but is rarely found in other papilionoids, corresponding to a hypothetically morphological synapomorphy in the pair Indigoferae plus millettioids.     

Inflorescence and floral development in Astragalus lagopoides Lam. (Leguminosae: Papilionoideae: Galegeae)

Inflorescence and floral organogenesis and development of the bushy perennial legume Astragalus lagopoides of the section Hymenostegis were studied by means of epi-illumination light microscopy. Based on our observations, the primordia of lanceolate racemose inflorescences are born in the axils of leaves. Each inflorescence apex initiates acropetally bracts and floral apices for some time and then eventually ceases meristematic activity and forms an oblong-shaped terminal structure. The formation of such atypical terminal protrusion on the inflorescence meristem is judged to be a diagnostic feature for well-organized cessation of meristem morphogenesis. Pentamerous perfect flowers of the plant show strong zygomorphy and marked overlap in time of initiation among different organ primordia. Unexpectedly, sepal initiation is bidirectional starting from the lateral sides of the floral apex. Other significant developmental feature includes the existence of two types of common primordia, which are formed successively. From the primary common primordia there are produced antesepalous stamens and secondary common primordia. In comparison, the five secondary common primordia subdivide into a petal and an antepetalous stamen primordia. Initiation of two different types of common primordia is possibly the result of rising overlap in time of initiation of organs and demonstrates an advanced developmental style in the genus Astragalus.     

Floral Development in Sonja White Clover (Trifolium repens) a Papilionoid Legume

Floral development in Sonja white clover was examined usingscanning electron microscopy. Florets and bracts were foundto arise from common primordia initiated as protuberances fromthe apical meristematic area of the inflorescence. The patternof floret initiation on the inflorescence was acropetal, theoldest florets resting basally. Floral organ initiation withineach floret was acropetal, petals being initiated before stamens.Floret development was zygomorphic, each whorl of floral organsdeveloping unidirectionally from the abaxial side. There wasfound to be overlapping in the timing of initiation and developmentof these organs. Antesepalous stamens were found initially tooutgrow their antepetalous counterparts. Early petal developmentwas synpetalous. Eglandular hairs were found basally on thecalyx cup and on the pedicel. Procumbent hairs were found tobe more numerous and randomly distributed on the abaxial surfacesof the mature calyx cup. Trifolium repens L., Sonja cultivar, white clover, scanning electron microscopy, floral development, inflorescence     

单性木兰（木兰科）花的形态发生

报道了单性木兰(Kmeria septentrionalis Dandy)花的形态发生过程。发现过去一直被认为是雌花条状披针形的“内轮花被片”,实际为退化雄蕊,它形态发生的时间与位置均与雄花的雄蕊相同,在成熟结构中仍可见药室残迹,说明单性木兰的雌性花是由两性花退化而来。通过与K. duperreana(Pierre) Dandy和Magnolia thailandica Noot. &; Chalermglin雌花的比较,发现它们雌花的形态相同,从而得知人们长期以来对此3种植物雌花的认识有误,原一直认为的“内轮花被片”实为退化雄蕊。     

Floral Morphogenesis of Anemone rivularis Buch.-Ham. ex DC. var.flore-minore Maxim. (Ranunculaceae) with Special Emphasis on Androecium Developmental Sequence

The floral morphogenesis and androecium developmental sequence of Anemone rivularis Buch.-Ham. ex DC. var. flore-minore Maxim. were observed under a scanning electron microscope (SEM)and by means of histological methods in order to expand our knowledge of the morphogenesis and development of the floral organs of the Ranunculaceae. The initiation of the floral elements is a centripetal spiral and the direction of the spiral is clockwise or anti-clockwise. However, the development of the androecium is highly unusual: in a longitudinal series of four stamens, the second stamen develops first from the inner to outer, then the third one, the fourth one and the first one in turn. The microsporogenesis and anther maturation follows the same developmental sequence. The tepals are different from the bracts and the stamens in both shape and size in the early developmental stage, but there is no difference between the stamens and carpels in the early developmental stage. Therefore, we established a spatio-temporal process of the floral morphogenesis of4. rivularis var.flore-minore and offer another meaning of the floral diversity patterns attributed to the level of the genus.     

THE DEVELOPMENTAL BASIS OF TRISTYLY IN EICHHORNIA PANICULATA (PONTEDERIACEAE)

Eichhornia paniculata is a tristylous, self-compatible, emergent aquatic. A given plant produces flowers with either long, mid or short styles and two levels of stamens equal in length to the styles not found in that flower. Flowers of each morph have two whorls of three tepals, six stamens and three fused carpels. The six stamens differentiate into two sets of three stamens each. A relatively short set, having either short- or mid-level stamens, occurs on the upper side of the flower, while a relatively long set, having either mid- or long-level stamens, occurs on the lower side. Stamen level depends on differences among stamens in filament length and position of insertion on the floral tube. Floral parts arise in whorls of three, but the two stamen whorls do not form the two sets of stamens found in each mature flower. Instead, stamens from both whorls make up a given set. Floral differences among morphs are not present at flower origin or floral organ initiation. Morphological differences arise first among stamen sets. The two sets within a flower differ prior to meiosis in the size, number, and timing of comparable developmental events in the sporogenous cells. After these initial differences arise, anther size diverges. In later developmental stages differences in filament and floral tube length, cell size, and cell number, as well as differences in the length, cell size, and cell number of styles, develop among morphs. This sequence of developmental events suggests that the genes controlling development in different morphs do not control flower and floral organ initiation but are first morphologically visible in sporogenous cell differentiation.