Discovery of Bisexual Flowers in Pterocarya Stenoptera C. DC.

This paper reports the bisexual structure of the flowers of Pterocarya stenoptera. The bisexual flowers are borne at the end of a leafy shoot of the current year in many-flowered terminal pendulous catkins. They have the same structure as the general female ones. Each flower grows in the axil of a bract, with a pair of bracteoles and four small perianths. Each flower has two or three carpels in the centre of the flower, and upon them there are two or three styles with stigmas on the inner face. They differ from the general female ones in that each of them contains 4-6 stamens, forming a single whorl. The stamens alternates with, or is opposite to, the perianth elements. Sometimes they contain 8 (-10) stamens, forming two whorls, with 6 in the outer whorl and 2 (-4) in the inner whorl, and in this case the pistil in the bisexual flower of terminal catkins often becomes a rudiment. It is interesting that we have also found bisexual flowers in another tree, which are borne in lateral male catkins. They have the same structure as general male ones, and the pistils are often represented by a rudiment. Manning (1940) points out that some female flowers of Pterocarya stenoptera and P. fraxinifolia occasionally have stamens ( ? ) opposite the sepals. In P. stenoptera we have found that both the stamens and the stigmas of bisexual flowers are functional. They are capable of producing functional fruits. This is the same case as in Myrica Gale described by Davey and Gibson (1917). Rendle (1952) points out that in the male flowers of Platycarya the pistils often appeared as a rudiment. He considers, however, the male flowers derived from the bisexual flowers with an indefinite number of stamens. The rudimentary pistils of lateral male catkins in P. stenoptera we found are just the same as the ones found in Platycarya by Rendle. The discovery of the bisexual flowers in P. stenoptera may prove that the unisexual flowers of the present-day Juglandaceae are derived from ancestors with bisexual flowers.This tends to support the hypothesis that Cycadicae is the possible ancestor of the angiosperms.     

大戟科麻疯树属三种植物花器官发生

利用扫描电子显微镜观察了大戟科Euphorbiaceae麻疯树属Jatropha麻疯树J. curcas L.、佛肚树J. podagrica Hook.和棉叶麻疯树J. gossypifolia L.花器官发生。结果表明: 麻疯树、佛肚树和棉叶麻疯树花萼原基均为2/5型螺旋发生。在同一个种不同的花蕾中, 花萼的发生有两种顺序: 逆时针方向和顺时针方向。远轴面非正中位的1枚先发生。5枚花瓣原基几乎同时发生。雄花中雄蕊两轮, 外轮对瓣, 内轮对萼。研究的3种麻疯树属植物雄蕊发生方式有两种类型: 麻疯树亚属麻疯树的5枚外轮雄蕊先同时发生, 5枚内轮雄蕊后同时发生, 佛肚树亚属佛肚树和棉叶麻疯树雄蕊8-9枚, 排成两轮, 内外轮雄蕊同时发生。雌花的3枚心皮原基为同时发生。麻疯树属单性花, 雌花的子房膨大而雄蕊退化, 雄花的雄蕊正常发育, 子房缺失。根据雄蕊发生方式, 支持将麻疯树属分为麻疯树亚属subgen. Jatropha和佛肚树亚属subgen. Curcas。     

NORMAL FLORAL ONTOGENY AND COOL TEMPERATURE-INDUCED ABERRANT FLORAL DEVELOPMENT IN GLYCINE MAX (FABACEAE)

Floral onset in soybean (Glycine max cv. Ransom) is characterized by precocious initiation of axillary meristems in the axils of the most recently initiated leaf primordium. During floral transition, leaf morphology changes from trifoliolate leaf with stipules, to a three-lobed bract, to an unlobed bract. Soybean flowers initiated at 26/22 C day/night temperatures are normal, papilionaceous, and pentamerous. Sepal, petal, and stamen whorls are initiated unidirectionally from the abaxial to adaxial side of the floral apex. The median sepal is located abaxially and the median petal adaxially on the meristem. The organogeny of ‘Ransom’ flowers was found to be: sepals, petals, outer stamens plus carpel, inner stamens; or, sepals, petals, carpel, outer stamens, inner stamens. The outer stamen whorl and the carpel show possible overlap in time of initiation. Equalization of organ size occurs only within the stamen whorls. The sepals retain distinction in size, and the petals exhibit an inverse size to age relationship. The keel petals postgenitally fuse along part of their abaxial margins; their bases, however, remain free. Soybean flowers initiated at cool day/night temperatures of 18/14 C exhibited abnormalities and intermediate organs in all whorls. The gynoecium consisted of one to ten carpels (usually three or four), and carpel connation varied. Fusion of keel petals was often lacking, and stamen filaments fused erratically. Multiple carpellate flowers developed into multiple pods that were separate or variously connate. Intermediate type organs had characteristics only of organs in adjacent whorls. These aberrant flowers demonstrate that the floral meristem of soybean is not fixed or limited in its developmental capabilities and that it has the potential to produce alternate morphological patterns.     

DIOECY IN BAUHINIA RESULTING FROM ORGAN SUPPRESSION

Bauhinia malabarica and B. divaricata have both been reported to have dimorphic flowers; floral development of these species has been investigated and compared using SEM. B. malabarica is subdioecious, with three types of flowers: perfect, staminate, and carpellate. Individual trees usually have only one type of flower. Perfect and carpellate flowers have similar initiation of floral organs; each has five sepals, five petals, two whorls of five stamen primordia and a carpel primordium. The carpels of carpellate flowers do not differ from those of perfect flowers throughout development. Both have a gynophore or stipe and a cuplike hypanthium. Stamen development diverges markedly after mid-development: the perfect flowers have ten stamens in two whorls, the outer with longer filaments than the inner. All stamens have anthers, which are covered abaxially with abundant inflated trichomes. Carpellate flowers have a circle of short cylindrical staminodia, each bearing a few hairs, about the base of the carpel on the rim of the hypanthium. Heteromorphy in B. malabarica is effected by suppression of stamen development, even though the usual number of stamen primordia is initiated. Suppression of stamens occurs at midstage in development in carpellate flowers of B. malabarica, and is complete. In B. divaricata nine stamen primordia are released from suppression in late stage, undergo intercalary growth and form a staminodial tube around the carpel stipe. The dimorphy in B. divaricata is expressed late in bud enlargement as divergent rates of growth in the carpel in the two morphs.     

Flower development in Abrus precatorius (Leguminosae: Papilionoideae: Abreae) and a review of androecial characters in Papilionoideae

The jequirity bean (Abrus precatorius) is well known because of its shiny black and red coloured seeds and because of the poison (abrin) it contains. The genus Abrus is placed in a monogeneric tribe Abreae which is placed in a relatively isolated systematic position at the base of Millettieae. To contribute to a better understanding of this taxon, a detailed ontogenetic and morphologic analysis of its flowers is presented. Floral primordia are subtended by an abaxial bract and preceded by two lateral bracteoles which are formed in short succession. Sepal formation is unidirectional starting abaxially. All petals are formed simultaneously. The carpel is formed concomitantly with the outer (antesepalous) stamen whorl, which arises unidirectionally, starting in an abaxial position. In the inner, antepetalous stamen whorl two abaxial stamens are formed first, followed by two lateral stamen primordia. The adaxial, antepetalous position remains organ free (i.e. this stamen is lost). Later in development the nine stamen filaments fuse to form an adaxially open sheath. The filament bases of the two adaxial outer-whorl stamens grow inwards, possibly to provide stability and to compensate for the lost stamen. In the mature flower a basal outgrowth can be found in the position of the lost stamen. However this is more likely to be an outgrowth of the filament sheath rather than a remnant of the lost stamen. These ontogenetic patterns match in parts those found in other Millettieae (unidirectional formation of sepals and stamens, simultaneous petal formation). In contrast, the complete loss of a stamen is rather unusual and supports the isolated position of Abreae and probably justifies (among other characters) its tribal status. A review of androecial characters shows that androecial merosity is on the one hand extremely variable among Leguminosae, varying from a single stamen per flower to more than 500. On the other hand it is noteworthy that the number of stamens becomes stabilised in more derived Papilionoideae such as the large non-protein-amino-acid-accumulating clade (NPAAA clade). This indicates that the androecium has played an important role in the success of a major part of Leguminosae.     

Flower development of Meliosma (Sabiaceae): evidence for multiple origins of pentamery in the eudicots

Flower developmental studies are a complement to molecular phylogenetics and a tool to understand the evolution of the angiosperm flower. Buds and mature flowers of Meliosma veitchiorum, M. cuneifolia, and M. dilleniifolia (Sabiaceae) were investigated using scanning electron microscopy to clarify flower developmental patterns and morphology, to understand the origin of the perianth merism, and to discuss the two taxonomic positions proposed for Sabiaceae, among rosids or in the basal grade of eudicots. Flowers in Meliosma appear pentamerous with two of the five sepals and petals strongly reduced, three staminodes alternating with two fertile stamens opposite the small petals, and a two-carpellate gynoecium. The flower development in Meliosma is spiral without distinction between bracteoles and sepals. Because of this development, sepals, petals, and stamens are almost opposite and not alternating as expected in cyclical pentamerous flowers. In four-sepal flowers the direction of petal initiation is reversed. The symmetry of the flower appears to be transversally zygomorphic, although this is hidden by the almost equal size of the larger petals. Evidence points to a unique pentamerous origin of flowers in Meliosma, and not to a trimerous origin, as earlier suggested, and adds support to multiple origins of pentamery in the eudicots.     

Genetic interactions among floral homeotic genes of Arabidopsis.

We describe allelic series for three loci, mutations in which result in homeotic conversions in two adjacent whorls in the Arabidopsis thaliana flower. Both the structure of the mature flower and its development from the initial primordium are described by scanning electron microscopy. New mutations at the APETALA2 locus, ap2-2, ap2-8 and ap2-9, cause homeotic conversions in the outer two whorls: sepals to carpels (or leaves) and petals to stamens. Two new mutations of PISTILLATA, pi-2 and pi-3, cause second and third whorl organs to differentiate incorrectly. Homeotic conversions are petals to sepals and stamens to carpels, a pattern similar to that previously described for the apetala3-1 mutation. The AGAMOUS mutations, ag-2 and ag-3, affect the third and fourth whorls and cause petals to develop instead of stamens and another flower to arise in place of the gynoecium. In addition to homeotic changes, mutations at the APETALA2, APETALA3 and PISTILLATA loci may lead to reduced numbers of organs, or even their absence, in specific whorls. The bud and flower phenotypes of doubly and triply mutant strains, constructed with these and previously described alleles, are also described. Based on these results, a model is proposed that suggests that the products of these homeotic genes are each active in fields occupying two adjacent whorls, AP2 in the two outer whorls, PI and AP3 in whorls two and three, and AG in the two inner whorls. In combination, therefore, the gene products in these three concentric, overlapping fields specify the four types of organs in the wild-type flower. Further, the phenotypes of multiple mutant lines indicate that the wild-type products of the AGAMOUS and APETALA2 genes interact antagonistically. AP2 seems to keep the AG gene inactive in the two outer whorls while the converse is likely in the two inner whorls. This field model successfully predicts the phenotypes of all the singly, doubly and triply mutant flowers described.     

Pseudodiplostemony, and its implications for the evolution of the androecium in the Caryophyllaceae

The androecium of the Caryophyllaceae is varied, ranging from a two-whorled condition to a single stamen. A number of species belonging to the three subfamilies, Caryophyl-loideae, Alsinoideae and Paronychioideae have been studied ontogenetically with the SEM to understand their peculiar androecial development in the broader context of the Caryophyllales alliance. Although patterns of initiation are highly variable among species, there are three ontogenetic modes of stamen initiation: all stamens simultaneous within a whorl, the antepetalous stamens simultaneous and the antesepalous sequentially with a reversed direction, or both whorls sequentially with or without a reversed direction. The most common floral (ontogenetic) sequence of the Caryophyllaceae runs as follows: five sepals (in a 2/5 sequence), the stamens in front of the three inner sepals successively, stamens opposite the two outermost sepals, five antepetalous stamens (simultaneously or in a reversed spiral superimposed on the spiral of the antesepalous stamens), five outer sterile (petaloid) organs arising before, simultaneously or after the antesepalous stamens, often by the division of common primordia. A comparison with the floral configurations of the Phytolaccaceae and Molluginaceae indicates that the outer petaline whorl of the Caryophyllaceae corresponds positionally to the alternisepalous stamens of somePhytolacca, such asP. dodecandra. The difference withP. dodecandra lies in the fact that an extra inner or outer whorl is formed in the Caryophyl-laceae, in alternation with the sepals. A comparable arrangement exists in the Molluginaceae, though the initiation of stamens is centrifugal. A comparison of floral ontogenies and the presence of reduction series in the Caryophyllaceae support the idea that the pentamerous arrangement is derived from a trimerous prototype. Petals correspond to sterillized stamens and are comparable to two stamen pairs opposite the outer sepals and a single stamen alternating with the third and fifth sepals. Petals are often in a state of reduction; they may be confused with staminodes and they often arise from common stamenpetal primordia. The antesepalous stamen whorl represents an amalgamation of two whorls: initiation is reversed with the stamens opposite the fourth and fifth formed sepals arising before the other, while the stamens opposite the first and second formed sepals are frequently reduced or lost. Reductive trends are correlated with the mode of initiation of the androecium, as well as changes in the number of carpels, and affect the antesepalous and antepetalous whorls in different proportions. It is concluded that the androecium of the Caryophyllaceae is pseudodiplos-temonous and is not comparable to diplostemonous forms in the Dilleniidae and Rosidae. The basic floral formula of Caryophyllaceae is as follows: sepals 5—petals 5 (sterile stamens)—antesepalous stamens 3+2—antepetalous stamens 5 gynoecium 5.     

FLORAL ONTOGENY OF ILLICIUM FLORIDANUM,WITH EMPHASIS ON STAMEN AND CARPEL DEVELOPMENT

The ontogeny of the flower and fruit of Illicium floridanum Ellis, the Star Anise, was investigated. Each of 5 or 6 bracts in each mixed terminal bud subtends either a vegetative or floral bud. The solitary flowers occur in terminal or axillary positions. Each flower has 3–6 subtending bracteoles arranged in a clockwise helix. The flowers in our material have 24–28 tepals, 30–39 stamens, and usually 13 (rarely 19) uniovulate carpels. Tepals and stamens are initiated in a low-pitched helix; carpels later appear whorled, but arise successively at different levels on the apical flanks. The floral apex is high-convex in outline with a tunica-corpus configuration; it increases in height and width throughout initiation of the floral appendages. Tepals, stamens, and carpels are initiated by one to several periclinal divisions in the subsurface layers low on the apical flanks, augmented by cell divisions in the outer layers of the corpus. The carpel develops as a conduplicate structure with appressed, connivent margins. Procambium development of floral appendages is acropetal and continuous. Bracteoles, tepals, stamens and carpels are each supplied by 1 trace; the carpellary trace splits into a dorsal and an ascending ventral sympodium. The latter bifurcates to form 2 ventral bundles. The ovular bundle diverges from the ventral sympodium. Ovule initiation occurs in a median axillary position to the carpel, an unusual type of ovule initiation. The fruit vasculature is greatly amplified as the receptacle and follicles enlarge. After carpel initiation an apical residuum persists which is not vascularized; a plate meristem develops over its surface to produce a papillate structure.     

舞花姜花部维管束系统的解剖学研究

对舞花姜(Globba racemosa)花部维管束系统进行解剖学观察分析,以探讨其缺失雄蕊的去向及其唇瓣和腺体结构的属性.结果显示:(1)舞花姜花梗部的维管束分散排列在基本组织内.(2)子房基部的维管束排成2部分,中央区为分散排列的小维管束,外方为一轮大维管束环,且外环维管束发育为子房壁维管束,心皮背束和隔膜束均起源于中心区维管束,二者的分支在延长部形成一个维管束网结;在网结之上,近轴面的两束心皮背束分支分别进入到2枚侧生退化雄蕊中并成为其主束,远轴面心皮背束的内方分支则成为唇瓣中束,三束心皮背束的其余分支均上行入萼片.(3)唯一1枚功能雄蕊接受近轴面隔膜束的内方主支作为其主束,远轴面2枚隔膜束的主支最后进入唇瓣的两侧束,三束隔膜束的外分支均发育为花瓣束.研究认为:舞花姜的唇瓣是一个三重结构,其中央维管束代表1枚外轮雄蕊,两侧维管束则分别代表2枚内轮雄蕊;舞花姜的2枚花瓣状退化雄蕊与唇瓣的中央一起构成外轮雄蕊,唯一1枚可育雄蕊和唇瓣的两侧同属内轮雄蕊.本研究结果支持姜科子房延长部形成的腺体属于子房上部心皮边缘的维管化附属物的观点.     

Homeotic, Meristic and Cytological Floral Mutants of Thryptomene calycina (family Myrtaceae)

Twenty plants with various phenotypic abnormalities to the flowerswere selected from very large populations of Thryptomene calycinain the Grampian and Black Ranges. Most of these had impairedreproductive function. Normal flowers were epigynous with fivesepals, five petals, five anthers, a single style and two anatropousovules. The mutants were two partially male sterile, tetraploidplants with large flowers, one of which occasionally producedadditional flowers from the leaf axils with peduncles as wellas pedicels; one plant which produced a proportion of hexapetaloidflowers with six stamens; three gross mutants with fleshy, bracteoidpointed petals and sepals, no stamens, vestigial styles andstigmas, exposed ovules and no inferior ovary; one plant withfleshly, bracteoid pointed sepals, vestigial style and stigmabut with exposed ovular structures replaced by four to fivesterile ovules generally inside an abnormal ovary; two plantswith reduced ovary diameter and sterile ovules, shortened style,five reduced sepals and petals and five to eight anthers; threeanthocyanin-free plants; three plants with pink sepals; twoplants with half-sized flowers which produced a proportion offasciated stems; one plant which occasionally produced flowerswithout pedicels which virtually resulted in organs which wereleaf-flower composites; two plants which produced sepals andpetals which contained chlorophyll and prematurely senesced,and had partial substitution of petals by anthers.Copyright1993, 1999 Academic Press Thryptomene calycina, Myrtaceae, Victorian lace flower, floral mutations, mutants, homeotic, meristic, tetraploid, fasciation, male sterility, cut flowers     

Notulae De Ranunculaceis Sinensibus(ⅩⅩⅡ)

(1) In the overwhelming majority of genera of the family Ranunculaceae, includ ing its primitive genera, Caltha, Calathodes, and Trollius and the primitive genus of trib. Anemoneae, Anemone, the sepals are spreading and the stamens are glabrous. So, the as cending or upright sepals and hairy stamens of the sections Meclatis, Tubulosa, Viorna, and Atragene of the genus Clematis are secondary, and are accordingly considered as advanced characters, and those sections and the genus Archiclematis, closely related to Sect. Viorna Subsect. Connatae, more or less advanced groups. (2) In the sections Cheiropsis, Fruticella, and Viticella, which have glabrous stamens,some species have spreading sepals, and the others have ascending or upright sepals. In Sect. Clematis, all the species have spreading sepals and glabrous stamens, except for Clematis pinnata, which has ascending sepals and usually hairy stamen filaments. In Sect. Lasiantha with 2 species restricted to western U. S. A., C. lasiantha has glabrous stamens, while C. paucifiora has stamens hairy on fliaments. In Sect. Naraveliopsis with spreading sepals,the majority of species have glabrous stamens, but one species, C.liboensis, endemic to Guizhou Province, China, has hairy stamens. These facts just mentioned indicate that the evolution of sepals and stamens took place in several lineages independently in Clematis. (3) In Clematis, glabrous stamens of C.apiifolia, C.grata, and C.montana with linear filaments and oblong anthers, are similar to those of Caltha, Calathodes, Trollius, and Anemone. Thus, the linear filaments and oblong anthers are considered primitive characters in Clematis. On the other hand, lanceolatelinear filaments of C. tangutica and C. aethusifolia or oblanceolate -linear filaments of C. courtoisii and C. loureiriana and linear anthers of C. meyeniana and C. uncinata, and narrow-linear anthers of C. courtoisii and C. lanuginosa are considered advanced ones. In ease of stamens with hairs, stamens of C. henryi with densely villous filaments and those of C. kweichowensis with both filaments and anthers densely pubescent show more advanced condition than those of C. pinnata, C. heracleifolia, and C. tangutica, with sparsely puberulous filaments and glabrous antbers(Fig. 1 ). (4)The pedunculate, 2-bracteate dichasial cyme with several flowers may represent the primitive type of inflorescences in Clematis. Manyflowered panicle-like cymes as in C.gouriana and C. tsaii, or few-l-flowered cymes as in C. henryi and C. repens, and cymes lacking peduncles and bracts as in C. montana and C. pogonandra are all considered advanced. Besides, the fact that flowers arise from axillary buds of old branches shows also an advanced condition. (5)Sect. Clematis subsect. Pinnatae, with leaflets, inflorescence ramification, and stamens similar to those of C. heracleifolia, is considered intermediate between Sect. Clematis and Sect. Tubulosa. (6) Subsect. Clematis and Subsect. Rectae, and Subsect. Connatae and Subsect. Crispae are so closely related to each other respectively that it is difficult to ascertain the systematic position of some intermediate species between the two subsections of each pair in the absence of seedlings. So, in the present paper, following the classification of Clematis proposed by Tamura in 1967, I put Subsect. Clematis and Subsect. Rectae in Sect. Clematis, and Subsect. Connatae and Subsect. Crispae in Sect. Viorna. (7)According to the evolutionary tendencies mentioned above, a realignment of the sections and the infrasectional taxa of the Chinese Clematis is made. (8) Six subsections, 6 serise, 2 species, and 4 varieties are described as new, and 5 new combinations, 4 new ranks, and 2 new names are given. (9)The specific rank of C. tenuipes W.T. Wang, reduced to varietal renk in 1980, is restord. C. taiwaniana Hayata, reduced to synonomy of C. grata Wall. in 1991, is considered distinct from the latter in hairy adaxial surface of sepal and narrower achene with tapering apex. C. kerriana Drumm. & Craib and C. laxipaniculata Pei are proved to be conspecific to C. subumbellata Kurz and reduced to syn-onymy.     

A comparative study of floral development inTrillium apetalon andT. kamtschaticum (Liliaceae)

Trillium apetalon Makino is unique amongTrillium in having apetalous flowers. Using scanning electron microscope, the early floral development was observed in comparison with that ofT. kamtschaticum Pallas ex Pursh having petalous flowers. Morphologically petal primordia closely resemble stamen primordia in their more or less narrow and radially symmetric shape and are clearly distinct from sepal primordia with broad bases. Early in floral development sepal primordia are first initiated and subsequently two whorls of three primordia each are formed in rapid sequence, the first three at the corners and the second three at the sides of the triangular floral apex. Based on comparison in position and early developmental processes of their primordia, petals and outer stamens ofTrillium kamtschaticum are equivalent to outer stamens and inner stamens ofT. apetalon. The replacement of petals by outer stamens apparently leads to the loss of petals inTrillium apetalon flowers. Such a replacement can be interpreted in terms of homeosis. The replacement of the petal whorl leads to the serial replacement of the subsequent whorls: outer stamens by inner stamens, and inner stamens by gynoecium inTrillium apetalon. The term ‘serial homeosis’ is introduced for this serial replacement.     

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.     

铁线莲属铁线莲组修订

(1)对毛莨科铁线莲属Clematis的铁线莲组sect.Viticella进行了分类学修订,确定此组包含13种,1亚种和2变种(包括2新种和1新变种等级),写出此组的分类学简史和地理分布;将此组划分为3亚组,4系,写出区分组下各级分类群的检索表,以及各种植物的形态描述,地理分布,生长环境等,并附有多幅插图。(2)特产我国东部的单型毛萼铁线莲亚组subsect.Hancockianae(花具4枚平展,不展宽的萼片,雄蕊无毛)被认为此组的原始群。铁线莲亚组subsect.Floridae(花具5-8枚平展,强烈展宽的萼片,雄蕊无毛,花粉具散孔)和湖州铁线莲亚组subsect.Viticellae(花具4枚渐升,多少展宽的萼片,雄蕊花丝常被缘毛,花粉具3沟)可能均由毛萼铁线莲亚组衍生而出。(3)在我国东部集中分布此组的3亚组,3系的8种,1亚种和1变种,这里是此组的分布中心,也可能是此组的起源中心。     

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.     

The floral development and floral anatomy ofChrysosplenium alternifolium, an unusal member of the Saxifragaceae

The floral development and anatomy ofChrysosplenium alternifolium were studied with the scanning electron microscope and light microscope to understand the initiation sequence of the floral organs and the morphology of the flower, and to find suitable floral characters to interpret the systematic position of the genus within the Saxifragaceae. The tetramerous flower shows a highly variable initiation sequence. The median sepals and first stamens arise in a paired sequence resembling a dimerous arrangement, but the first sepal and stamen arise on the side opposite to the bract. Transversal sepals and stamens emerge sequentially, as one side often precedes the other; sepals and stamens occasionally arise on common primordia. Initiation of the gynoecium is more constant with two median carpel primordia arising on a sunken floral apex. Several flowers were found to be pentamerous with a 2/5 initiation sequence. Flowers were invariably found to be apetalous without traces of petals in primordial stages; this condition is interpreted as an apomorphy. It is postulated that the development of a broad gynoecial nectary is responsible for the occurrence of an obdiplostemonous androecium. The gynoecium shows a number of anatomical particularities not observed in other Saxifragaceae. The presence and distribution of colleters is discussed.     

Comparative floral structure and systematics in Oxalidales (Oxalidaceae, Connaraceae, Brunelliaceae, Cephalotaceae, Cunoniaceae, Elaeocarpaceae, Tremandraceae)

Floral morphology, anatomy and histology were studied in representatives of all families of current Oxalidales, which were recently constituted as a result of molecular systematic studies by other authors, and are composed of families of different positions in traditional classifications (Oxalidaceae, Connaraceae, Brunelliaceae, Cephalotaceae, Cunoniaceae, Elaeocarpaceae, Tremandraceae). Two of the three pairs of sister (or nested) families that come out in molecular analyses are highly supported by floral structure: Oxalidaceae/Connaraceae and Elaeocarpaceae/Tremandraceae, whereas Cephalotaceae/Cunoniaceae are not especially similar at the level of Oxalidales. Oxalidaceae and Connaraceae share petals that are postgenitally united into a basal tube (although they are imbricate in both) but free at the insertion zone, stamens that are congenitally united at the base, uniseriate glandular hairs on the stamen filaments, and ovules that are hemianatropous to almost orthotropous. The sharing of a special type of sieve-tube plastids and of trimorphic heterostyly, studied by other authors, should also be mentioned. With Brunelliaceae, the two families share an androgynophore and nectaries at the base of the stamens in alternisepalous sectors. Elaeocarpaceae and Tremandraceae share buzz-pollinated flowers and a syndrome of features functionally connected with it. In addition, petals are larger than sepals in advanced bud, they are valvate, involute and enwrap part of the adjacent stamens, they have three vascular traces. Lignified hairs are common on the anthers and are found in the ovary locules and on the ovules (not lignified) of representatives of both families. Ovules have a chalazal appendage, and the inner integument is much thicker than the outer.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 140 , 321–381.     

Comparative floral development and evolution in tribe Caesalpinieae (Leguminosae: Caesalpinioideae). Haematoxylum

Floral organogenesis and development of the tropical legume trees Haematoxylum campechianum (logwood) and H. brasiletto (brazilwood) were studied using scanning electron microscopy. The aims were to compare ontogenies, and to elucidate the relationships of Haematoxylum with other genera of Caesalpinieae, the basal tribe of Caesalpinioideae. Flowers of Haematoxylum are in racemes or fascicles, lack bracteoles, and are pentamerous, hermaphroditic, and either actinomorphic or zygomorphic. Whorls arise in acropetal order except for the carpel, which arises concurrently with the outer stamens. Sepal order is bidirectional (a rare condition) within the whorl in both. Petals and outer stamens are initiated bidirectionally in H. campechianum, and unidirectionally in H. brasiletto. Inner stamens are initiated unidirectionally in both. In H. campechianum, time of petal initiation overlaps with that of outer stamens, and initiation of the two stamen whorls overlap. In both, the gynoecium becomes stipitate, and a hypanthium forms late in development. Both show many plesiomorphic states at anthesis; H. brasiletto alone shows several specialized states (expressed late in development), including a fused, gibbous calyx cup, a zygomorphic corolla, lightly aggregated filaments held together by hairs, and fenestrations in the stamen column. Ontogenetic divergence late in ontogeny characterizes differences at anthesis between related species.     

Pentamerous flowers in the genus Phytolacca have been derived from trimerous flowers—New evidence from the floral organogenesis of Phytolacca dodecandra

The floral organogenesis of Phytolacca dodecandra L′Her. (Phytolaccaceae) has been observed under both scanning electron microscope (SEM) and light microscope. The primordia of the floral appendage are arranged according to a pentamerous pattern and acropetal succession. Five sepal primordia arise in a 2/5 sequence, and no petal primordia have been observed. The stamen primordia arise centrifugally. The first two pairs arise successively opposite sepal one and two. In the subsequent initiation of inner and outer stamens, P. dodecandra differs from other species in the genus Phytolacca. The four or five carpel primordia arise in rapid succession, usually equal in number and alternating with the inner stamens. The effects of temporal and spatial factors during the floral organogenesis of P. dodecandra are discussed. The data on the androecial ontogeny in P. dodecandra refute the existence of diplostemony in Phytolaccaceae, in which P. dodecandra occupies a pivotal systematic position. The androecial ontogeny in P. dodecandra supports the viewpoint that in the genus Phytolacca pentamerous flowers have been derived from trimerous flowers.