THE ONTOGENY OF THE INFLORESCENCE AND FLOWER OF LIQUIDAMBAR STYRACIFLUA L. (HAMAMELIDACEAE)

A developmental study of the inflorescence of Liquidambar styraciflua L. was conducted to clarify morphological discrepancies reported in the literature. Salient features of development are: 1) the inflorescence apex results from the conversion of a terminal, vegetative apex; 2) partial inflorescence apices arise as ellipsoid structures in axils of leaves, bracts, or transitional phyllomes; 3) development of male heads is acropetal whereas female heads differentiate basipetally; 4) the partial inflorescence apex becomes segmented into several distinct subunits indicating an axillary branch system of the third order; 5) distinct individual floral primordia are initiated on the subunits; 6) a complete absence of perianth development; 7) inception of carpel primordia in flowers of lower male heads as well as female heads, but a failure of the gynoecium to develop beyond an incipient stage in male heads; and 8) development of sterile structures around the base of the styles of only female flowers near the time of anthesis. Carpellary characteristics of the sterile structures are described, their morphological nature is discussed, and the phylogenetic position of Liquidambar is evaluated.     

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.     

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.     

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。     

花叶芋(天南星科)的花器官发生

利用扫描电镜首次观察了天南星科花叶芋(Colocasia bicolor) 的花器官发生过程。花叶芋的肉穗花序由无花被的单性花构成, 雌花发生于花序基部, 雄花发生于花序上部, 中性花位于花序中间部位。雄花: 3 或4 个初生雄蕊原基轮状发生, 随后每个初生原基一分为二, 形成6或8个次生原基; 一部分次生原基在其后的发育过程中融合, 形成5 或7 枚雄蕊; 雄花发育过程中未见雌性结构的分化; 花药的分化先于花丝; 雄蕊合生成雄蕊柱。雌花: 合生心皮, 3或4个心皮原基轮状发生, 未见雄性结构的分化。中性花来源于雌雄花序过渡带上, 属于雄蕊原基的滞后发育以及发育成熟过程中的退化; 与彩叶芋属(Caladium)不同, 此过渡区未见畸形两性花。初生雄蕊原基二裂产生次生原基的次生现象在目前天南星科花器官发生中显得比较特殊, 同时初步探讨了次生原基的融合方式。     

Vaxiations in floral development in Peperomia (Piperaceae) and their taxonomic implications

The floral development of two species of Peperomia, Peperomia reflexa A. Dietr. (P. tetraphylla (G. Font.) Hook. et Am.) and P. serpens C. DC., is described. The initiation order is in an acropetal succession and resembles that in P. metallica L. Lind. et Rod., P.pellucida (L.) Kunth and P. rubella Hook., although many more bracts are produced in these two species than in P. metallica. The arrangement of bracts and floral primordia is orthostichous in P. reflexa, but parastichous in P. serpens. The floral apices in P. reflexa are transversely ellipsoidal protuberances at first, then become saddle-shaped when they begin to produce simultaneously staminal primordia. They are similar to those of P. metallica, P. pellucida and P. rubella. However, their initiation of floral primordia is much delayed compared to the size of the bracts. The triangular or transvcrsely cuneate ridges then become L-shaped in P. serpens, this shape is related to the parastichous phyllotaxy of the bracts. So, the staminal primordia are successively initiated and develop at different rates. Therefore, they are not always the same size. The staminal primordia are initiated above the level of the floral apex in P. reflexa and P. serpens but below it in P. metallica, P. pellucida and P. rubella. The abaxial position of the carpel primordium on the apex and the closure of the ovary in P. reflexa and P. serpens are also similar to those in P. metallica, P. pellucida and P. rubella. The shape of the upper part of the ovary, stigmas and indumentum vary between the species. In P. reflexa, the upper part of the ovary becomes ovoid and acclivous, or leaning acropetally, to the axis of inflorescence. In P. serpens, it becomes helmet-shaped. The flowers of P.serpens are surrounded by the outgrowth of the axis of the inflorescence. The ontogenetical features of ovaries in Peperomia indicate that the fruit characters are useful in the taxonomy of the genus.     

Distribution of Lateral Root Primordia in Root Tips of Musa acuminata Colla

The distribution of lateral root primordia in Musa acuminatashows discrete elements of pattern, a major element of whichis the rather regular spacing of laterals along protoxylem-basedranks. There is some co-ordination of positions of lateralsin different ranks. Laterals are apparently not initiated ina single acropetal sequence within the root tip as a whole althoughthey are initiated in acropetal sequence within each rank. Musa acuminata, banana, roots, lateral roots     

泽苔草的花器官发生

本文用扫描电镜观察了泽苔草的花器官发生过程,观察结果表明：花萼以螺旋状方式向心发生,花瓣以接近轮状方式近同时发生,不存在花瓣雄蕊复合原基。雄蕊和心皮均以轮状向心方式发生,6枚雄蕊分两轮分别在对萼和对瓣的位置先后发生,至发育的后期排成一轮,但仍分别处于对萼和对瓣的位置;随后发生的第一轮3个心皮原基与3枚萼片相对,第二、三轮心皮原基分别为1~3个,与前一轮心皮相间排列向心发生。本文首次揭示了泽苔草花被的外轮3个萼片螺旋状发生方式,这种螺旋状方式很可能是泽泻科植物的花部结构在进化过程中适应环境而保留下来的一种较原始的叶性特征。     

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.     

FLORAL DEVELOPMENT IN GYMNOTHECA CHINENSIS (SAURURACEAE)

The development of the inflorescence and flowers are described for Gymnotheca chinensis Decaisne (Saururaceae), which is native only to southeast China. The inflorescence is a short terminal spike of about 50–70 flowers, each subtended by a small bract. There are no showy involucral bracts. The bracts are initiated before the flowers, in acropetal order. Flowers tend to be initiated in whorls of three which alternate with the previous whorl members. No perianth is present. The flower contains six stamens, and four carpels fused in an inferior ovary containing 40–60 ovules on four parietal placentae. Floral symmetry is dorsiventral from inception and throughout organ initiation. Floral organs are initiated in the following order: 1) median adaxial stamen, 2) a pair of lateral common primordia which bifurcate radially to produce two stamen primordia each, 3) median abaxial stamen, 4) a pair of lateral carpel primordia, 5) median adaxial carpel, 6) median abaxial carpel. This order of initiation differs from that of any other Saururaceae previously investigated. The inferior ovary results from intercalary growth below the level of stamen attachment; the style elongates by intercalary growth, and the four stigmas remain free. The floral structure of Gymnotheca is relatively advanced compared to Saururus, but its assemblage of specializations differs from that of either Anemopsis or Houttuynia, the other derived genera in the Saururaceae.     

ORGAN INITIATION AND DEVELOPMENT OF INFLORESCENCES AND FLOWERS OF ACACIA BAILEYANA

Inflorescence and floral ontogeny are described in the mimosoid Acacia baileyana F. Muell., using scanning electron microscopy and light microscopy. The panicle includes first-order and second-order inflorescences. The first-order inflorescence meristem produces first-order bracts in acropetal order; these bracts each subtend a second-order inflorescence meristem, commonly called a head. Each second-order inflorescence meristem initiates an acropetally sequential series of second-order bracts. After all bracts are formed, their subtended floral meristems are initiated synchronously. The sepals and petals of the radially symmetrical flowers are arranged in alternating pentamerous whorls. There are 30–40 stamens and a unicarpellate gynoecium. In most flowers, the sepals are initiated helically, with the first-formed sepal varying in position. Petal primordia are initiated simultaneously, alternate to the sepals. Three to five individual stamen primordia are initiated in each of five altemipetalous sectorial clusters. Additional stamen primordia are initiated between adjacent clusters, followed by other stamens initiated basipetally as well as centripetally. The apical configuration shifts from a tunica-corpus cellular arrangement before organogenesis to a mantle-core arrangement at sepal initiation. All floral organs are initiated by periclinal divisions of the subsurface mantle cells. The receptacle expands radially by numerous anticlinal divisions in the mantle at the summit, concurrently with proliferation of stamen primordia. The carpel primordium develops in terminal position by conversion of the floral apex.     

宽叶泽苔草的花器官发生

通过扫描电镜观察了宽叶泽苔草Caldesia grandisSamuel.的花器官发生。宽叶泽苔草 的萼片3枚,逆时针螺旋向心发生 ;花瓣3枚,呈一轮近同时发生,未观察到花瓣_雄蕊复合原基;雄蕊、心皮原基皆轮状向心 发生,最先近同时发生的6枚原基全部发育成雄蕊,随后发生的6枚原基早期并无差别,在发 育过程中逐渐出现形态差异,直至其中1－4枚发育成心皮,其余的发育成雄蕊;而后的几轮 心皮原基,6枚一轮,陆续向心相间发生。本文揭示了3枚萼片螺旋状的发生方式,并推测这种螺旋方式是泽泻科植物进化过程中保留下来     

Floral development of dioecious species and trends of floral evolution in Piper sensu lato

The initiation of the floral parts (mainly stamens and carpels) is described for the four dioecious species of Piper: Piper polysyphorum C. DC, P. bavinum C. DC., P. pedicellatum C. DC., P. pubicatulum C. DC. The initiation order resembles that in the perfect flowers of some species, such as P. amalago. The carpels are initiated simultaneously, in most cases, as three primordia. In P. polysyphorum , carpel tips split into two lobes, so that finally a four- or five-lobed stigma will be formed when the ovary is fully developed. The staminodes (exactly, staminodial primordia) in the female flowers are initiated in the same order as the stamens in the male flowers and remain until the ovaries are enclosed. The unisexual flowers have stamens reduced to three or two. The reduction of stamen or staminode (staminodial primordium) number is accompanied by the change of their positions from opposite the carpels to alternate. After the initiation of the staminodes, or, exactly staminodial primordia, in the female flowers, the central part of the floral apex forms a ring meristem which is triangular. The carpel primordia (often three) are initiated on the three points of the ring meristem. The evolutionary trends of the flowers of Piper sensu lato are discussed.     

ANATOMY AND DEVELOPMENT IN SOLISIA

Boke , Norman H. (U. Oklahoma, Norman.) Anatomy and development in Solisia. Amer. Jour. Bot. 47(1): 59—65. Illus. 1960.–The genus Solisia contains a single species of small cacti which resemble certain mammillarias in having: pink, lateral flowers; milky juice; and dimorphic areoles. Adult specimens have elongate spiniferous areoles with an unusual sequence of spine initiation. The first four or five primordia appear at the posterior end of the areole meristem; the next are initiated near its center, after which initiation proceeds both acropetally and basipetally until the single, elliptical series of primordia is complete. A similar pattern of spine initiation occurs in Pelecyphora aselliformis, but this species differs markedly from S. pectinata in other respects. In seedlings of S. pectinata the areoles are broadly elliptical and spine initiation is strictly acropetal, a situation found in certain species of Mammillaria. Seeds of S. pectinata are black with a large hilum and a small perisperm. Since the perisperm has apparently been overlooked, it appears that only the black seed coat and relatively large hilum keep the species out of Mammillaria. If Buxbaum's postulates concerning the value of seed structure in tracing phylogeny in the Cactaceae are valid, S. pectinata must have diverged from the main line of evolution somewhere below Neobesseya. In that event, the species probably merits generic rank; otherwise, it seems preferable to return it to Mammillaria.     

HELICAL FLORAL ORGANOGENESIS IN GLEDITSIA,A PRIMITIVE CAESALPINIOID LEGUME

In order to determine the extent of floral ontogenetic differences among species of a genus, six species of Gleditsia were studied. Gledilsia is one of only two leguminous genera known in which there is completely helical succession of floral organs. Floral ontogeny was compared in three species (Gleditsia amorphoides, G. aquatica, and G. triacanthos), and late stages in six species (including the first three plus G. caspica, G. delavayi, and G. japonica). Other unusual primitive developmental features include the unequal-sized flower primordia which produce flowers of variable merosity. Order of floral development is also loosely controlled, so that flowers of different growth stages are intermixed in the inflorescence. Variable features include the occurrence of floral bracts, merosity of flowers, number of organs, and position of the first organ (sepal) initiated. The inflorescence type, while usually a raceme, often has lateral branches near the base, or fascicles of flowers at some points. A terminal flower often is present, although not in all species. Sex of flowers and inflorescences also varies, although floral initiation tends to include both stamens and carpel primordia. Suppression of one or the other may occur at different stages of development. Carpel orientation also varies; the cleft may be tilted or inverted occasionally. It is proposed that absence of subtending floral bracts influences development so as to favor radial symmetry and establishment of other “chaotic” characters seen in Gledilsia flowers.     

Floral ontogeny in Swartzia (Leguminosae: Papilionoideae: Swartzieae): distribution and role of the ring meristem

The anomalous systematic position of Swartzieae at the base of Papilionoideae is correlated with unusual developmental features: one petal or none; a ring meristem; polystemony; heterostemony; little or no alignment of stamens as antesepalous or antepetalous; multicarpely; and absence of unidirectional order of organs except in the calyx. Symmetry is zygomorphic throughout development. Floral ontogeny of four species of Swartzia reveals five sepals are initiated successively, beginning abaxially, but intercalary growth below the separate sepals forms a tubular calyx that splits irregularly, a feature typifying the genus. A single petal is initiated adaxially or may be missing altogether (in S. sericea). The apex enlarges and forms a ring meristem concurrently with carpel initiation. Several large-stamen primordia (2-15, according to the species) initiate first on the ring, followed by 40-150 small-stamen primordia. The latter initiate in centrifugal order in S. aureosericea and S. laurifolia or in acropetal order in S. sericea and S. madagascariensis. While ring meristems are considered to be homologous among Neotropical species studied as well as in the African S. madagascariensis, they vary in extent, duration, order of initiation, and productivity. Swartzieae is unlikely to be ancestral to the rest of Papilionoideae, based on radically differing floral ontogeny in the two groups.     

Pistillate and staminate flower development in dioecious Pistacia vera (Anacardiaceae)

The development of staminate and pistillate flowers in the dioecious tree species Pistacia vera L. (Anacardiaceae) was studied by scanning electron microscopy with the objective of determining organogenetic patterns and phenology of floral differentiation. Flower primordia are initiated similarly in trees of both sexes. Stamen and carpel primordia are initiated in both male and female flowers, and the phenology of organ initiation is essentially identical for flowers of both sexes. Vestigial stamen primordia arise at the flanks of pistillate flower apices at the same time functional stamens are initiated in the staminate flowers. Similarly, a vestigial carpel is initiated in staminate flowers at the same time the primary, functional carpel is initiated in pistillate flower primordia. Differences between the two sexes become apparent early in development as, in both cases, development of organs of the opposite sex becomes arrested at the primordial stage. Male flowers produce between four and six mature functional stamens and female flowers produce a gynoecium with one functional and two sterile carpels.     

茄科马尿泡和天仙子的花器官发生

利用扫描电镜研究了茄科 (Solanaceae)天仙子族 (Hyoscyameae)中国特有属马尿泡属 (PrzewalskiaMaxim .)马尿泡 (PrzewalskiatanguticaMaxim .)和天仙子属 (HyoscyamusL .)天仙子 (HyoscyamusnigerL .)的花器官发生和发育 ,研究结果表明 :马尿泡和天仙子花器官的发生和发育具有以下 3个共同特征 :1)符合Hofmeister规律 ,即新器官的发生首先出现在花顶已经存在的器官之间 ;2 )花冠的发育模式符合茄科植物所具有的“后合瓣”(“latesympetaly”)现象 ,即花瓣单独发生但后来又通过它们基部分生组织的融合而连合起来 ;3)花被五基数且花器官原基发生顺序为向心发育。但是它们的花萼原基具有不同的发生方式。天仙子花萼裂片原基的发生方式为环状发生 ;马尿泡花萼裂片原基的发生方式为螺旋状发生 ,但 5个花萼裂片原基在都出现后就连成了一个环。马尿泡是介于天仙子属和山莨菪属之间的类群 ,它比天仙子属原始但较山莨菪属进化。     

ONTOGENY OF THE INFLORESCENCE OF SAURURUS CERNUUS (SAURURACEAE)

The spicate inflorescence of Saururus cernuus L. (Saururaceae) results from the activity of an inflorescence apical meristem which produces 200–300 primordia in acropetal succession. The inflorescence apex arises by conversion of the terminal vegetative apex. During transition the apical meristem increases greatly in height and width and changes its cellular configuration from one of tunica-corpus to one of mantle (with two tunica layers) and core. Primordia are initiated by periclinal divisions in the subsurface layer. These are “common” primordia, each of which subsequently divides to produce a floral apex above and a bract primordium below. The bract later elongates so that the flower appears borne on the bract. All common primordia are formed by the time the inflorescence is about 4.4 mm long; the apical meristem ceases activity at this stage. As cessation approaches, cell divisions become rare in the apical meristem, and height and width of the meristem above the primordia diminish, as primordia continue to be initiated on the flanks. Cell differentiation proceeds acropetally into the apical meristem and reaches the summital tunica layers last of all. Solitary bracts are initiated just before apical cessation, but no imperfect or ebracteate flowers are produced in Saururus. The final event of meristem activity is hair formation by individual cells of the tunica at the summit, a feature not previously reported for apical meristems.     

FLORAL DEVELOPMENT IN SAURURUS CERNUUS (SAURURACEAE): 1. FLORAL INITIATION AND STAMEN DEVELOPMENT

The inflorescence of Saururus cernuus L. produces lateral “common” primordia in acropetal succession on the flanks of the inflorescence meristem; curiously, the “subtending” bract is initiated upon the lateral primordium rather than subtending it. On the basis of mature floral structure, flowers of S. cernuus have previously been described as having spiral initiation of parts. The current ontogenetic investigation contradicts this interpretation. Stamens arise in three successive pairs; the carpels also are initiated in pairs. Floral symmetry is shown to be bilateral from the onset of organ initiation, a rare feature among primitive angiosperms. On the basis of symmetry and paired initiation of organs, the possibility of close relationships between Saururaceae and Magnolialian or Ranalian lines appears remote.