商陆属2种植物花器官发生过程观察

该研究采用扫描电镜观察红蕊商陆(Phytolacca esculenta)和浙江商陆(Phytolacca zhejiangensis)的花器官发生过程,以明确商陆属植物花的基数,以及雄蕊和雌蕊是否具有叶性器官发生的特点,阐明商陆属植物花发生的模式。观察结果显示:(1)红蕊商陆和浙江商陆在花原基发生后,小苞片以2/5圆周相继发生,花被片的发生紧接小苞片的发生进行,花被与小苞片的发生均有顺时针和逆时针方向,且二者的发生方向始终一致。(2)花被发生结束后,雄蕊在花顶端分生组织的环状分生组织上发生,没有明显的发生顺序,近似同时发生;2轮雄蕊时内轮雄蕊先发生;外轮雄蕊有少数有时偶然与花被互生,但因外轮雄蕊数多于花被数,雄蕊与花被常不互生,也没有规律性。(3)红蕊商陆和浙江商陆的心皮都在雄蕊发生后,紧接着开始发生,且雌蕊与雄蕊(或内轮雄蕊)互生发生;心皮没有发生的先后次序,且每个心皮在基部连成一个整体形成雌蕊基部并发育成为子房。(4)红蕊商陆和浙江商陆的花基数为5,雄蕊和雌蕊的发生及数目不符合5基数的特点。研究认为,红蕊商陆和浙江商陆为5基数花,该研究结果不支持商陆属植物为3基数花的发生模式。     

Generic limits in Polygonurn and related genera (Polygonaceae) on the basis of floral characters

In order to investigate the taxonomic value of a number of characters in the elucidation of relationships within the collective genus Polygonum L., and segregate genera Atraphaxis L., Calligonum L., Pteropyrum Jaub. & Spach., Oxygonum Burch., Fagopyrum Mill., Harpagocarpus Hutch. & Dandy and Polygonella Michx., 83 species of the tribe Polygoneae emend. Jaretzky were studied. The following floral characters were examined: stamen number, insertion and external morphology; structure and morphology of the floral nectaries; vasculature and surface morphology of the tepals.
Problems in floral morphology in Polygonaceae are discussed, together with relationships within the Family. The tribal division proposed by Haraldson (1978) is supported, but a new and different delimitation of genera is proposed. The present data support a division of Polygonum L. sensu lato and its related taxa into two tribes: Polygoneae (containing Polygonum L. sensu stricto, Fallopia Adans., Oxygonum Burch., Pteropyrum Jaub. & Sparh., Atraphaxis L. and Calligonum L.), and Persicarieae (containing Fagopyrum Mill., Harpagocarpus Hutch. & Dandy, Persicaria Mill. and Koenigia L.). The genus Reynoutria Houtt. is included as a section of Fallopia Adans.; Bislorta Mill., Aconogonon Reichenb. and Tovara Adans. are included within Persicaria Mill.
A number of new combinations are proposed in Persicaria and Fallopia .     

Initiation of primary vascular elements in the stamens and carpel of Triticum aestivum L.

The primary vascular elements originate in the procambia of the single carpel and three stamens of the floret independently and in isolation from the vascular system of the spikelet. The initiation of protophloem elements is earlier in the stamens than in the carpel. The median strand of the carpel differentiates before the two lateral strands. The protoxylem elements are initiated after the protophloem elements are welt differentiated.
The differentiation of both protophloem and protoxylem elements is bidirectional in the stamens and in the three strands of the carpel, whereas their differentiation is acropetal in the funicular strand of the carpel.     

Floral ontogeny of Knema and Horsfieldia (Myristicaceae): evidence for a complex androecial evolution

The floral ontogeny of two species of Knema and one of Horsfieldia was examined and described using scanning electron microscopy. The perianth is trimerous with three tepals arising in succession. Pistillate flowers have a rounded floral apex with a convex top. The single carpel primordium is initiated along the margin of the bud and develops a plicate shape with an apical bilobed stigma. In staminate flowers, the floral apex is broadly hemispherical with a somewhat three‐sided shape. Several anther primordia are initiated almost simultaneously around the margin of the floral apex. In Horsfieldia, stamens extend laterally in antetepalous groups, whereas, in Knema, anthers form two whorls. The alternitepalous stamens were found to be different from the antetepalous stamens, which are pressed within a limited space. The anther primordia remain adnate to the receptacle and grow longitudinally, producing a pair of microsporangia. The central area of the floral apex persists as an undifferentiated residuum without any trace of a gynoecium. Myristicaceous anthers are basically homologous, although the number of anthers, pollen sacs and shape of the androecium are variable. The evolution of the androecium is discussed in the family, with opposing possibilities for reductions and increases in anther number in Myristicaceae. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 42–52.     

两性花的雄蕊运动:多样性和适应意义

雄蕊运动指雄蕊在自身能量支持下发生的主动运动,不包括雄蕊在访花者触碰下造成的被动位移。该文总结了雄蕊的应激运动、快速猛烈弹射、缓慢运动以及级联运动等4种主要类型,分析了这些运动类型的系统分布及繁殖适应意义等方面的研究进展。雄蕊的应激运动由访花者或其他外力诱发,可能起到促进散粉和实现繁殖保障的作用;雄蕊快速猛烈的弹射运动可将花粉猛然撒向空中或访花者身上,促进了花粉的风媒或虫媒散布;缓慢运动的雄蕊可能通过在不同花期改变雄蕊的空间位置和雌雄异位程度来调节繁殖策略,或主动将雄蕊花药移至特定部位(如柱头表面)实现自交;雄蕊逐一、依次发生的级联运动较为复杂,主要分布在刺莲花科、梅花草科、旱金莲科和芸香科中,目前还缺乏实验研究;但根据"花粉呈现理论"以及其他类型的雄蕊运动研究结果,雄蕊的级联运动可以将花粉分批呈现给不同的传粉者,通过不同传粉者的分别传粉来提高花粉的输出;而且可避免已散粉雄蕊对即将散粉雄蕊的干扰,同时可能也降低了雌雄功能干扰和(或)花内自交。在芸香(Ruta graveolens)中,级联运动之后的雄蕊还会在花末期再同时向花中央运动;这种多向、多次运动方式是目前发现的最复杂的雄蕊运动类型。雄蕊运动领域值得今后开展进一步实验研究的方向主要有:1)雄蕊运动尤其是级联运动对雌雄功能干扰(性别间干扰)、雄蕊与雄蕊的"性别内干扰"等植物繁殖格局的影响;2)雄蕊运动与雌雄异熟、雌雄异位等花部特征的相互作用;3)雄蕊运动复杂类型的生理与发育机制。     

Phenotypic gender in Hormathophylla spinosa (Brassicaceae), a perfect hermaphrodite with tetradynamous flowers, is variable

Angiosperms show an evolutionary trend from an indefinite to a fixed number of floral organs. When floral formula inconstancy in recent angiosperms is reported, it is often considered as a byproduct of stress and its fitness consequences remain mostly unexplored. We report substantial nonhomeotic meristic variation in stamen number (0–10 stamens per flower) in two populations of Hormathophylla spinosa during four years. This variation was plastic, suggesting its functional role in the adjustment of phenotypic gender. However, no correlations were found between phenotypic gender and plant size, pollinator or herbivore abundance. Effects on female reproductive success were inconsistent on a per-flower and on a per-plant basis, rendering adaptive explanations in terms of selfing or resource adjustment unsatisfactory with the data available. Nevertheless, individuals showing larger interannual variation in phenotypic gender showed higher female reproductive success, suggesting an advantage for gender modification. Although our results do not easily conform to any adaptive explanation, this remarkable example of breakdown of trait canalization should stimulate the study of the mechanisms and ultimate causes responsible for the maintenance of fixed floral traits.     

二倍体普通荞麦异常花朵及其结构的研究

在二倍体普通荞麦BW1 9 1的自交后代群体中有一些植株上的很多花朵形态及其结构发生变异。对这些异常花朵的形态进行了观察 ,统计了各变异花朵的被片数目 (x1)、花柱数目 (x2 )、胚珠数目 (x3 )和雄蕊数目 (x4)等参数。结果发现 ,该群体植株的花朵类型多达 2 5种以上。同一植株上花朵的被片数目 (x1)、花柱数目 (x2 )、胚珠数目 (x3 )和雄蕊数目 (x4)等参数变异广泛。大多数花朵为 5被片 3花柱 1胚珠 8雄蕊 ,但是被片数变幅为 3～ 8,雄蕊数变幅为 3～ 1 1 ,花柱数变幅为 2～ 8,胚珠数变幅为 1～ 3。当花柱数分别为 2、3、4、5、6、7或 8时 ,胚珠数分别是 1 (正常 )、1 (正常 )、1 (正常 ) +0 (未发育胚珠 )、1 (正常 ) +1 (小型胚珠 )、2 (正常 )、2 (正常) +0 (未发育胚珠 )或 2 (正常 ) +1 (小型胚珠 )。偏相关分析表明 ,被片数与花柱数存在显著相关 (r12 .3 4 =0 2 3 0 2 ) ,被片数与雄蕊数存在极显著相关 (r14 .2 3 =0 .472 7 )以及花柱数与胚珠数之间存在极显著相关(r2 3 .14 =0 .7787 ) ,这暗示被片、花柱、胚珠、雄蕊在遗传或发育上是相关的     

Intrafloral differentiation of stamens in heterantherous fowers

Flowers that have heteromorphic stamens (heterantherous flowers) have intrigued many researchers ever since the phenomenon was discovered in the 19th century. The morphological differentiation in androecia has been suggested as a reflection of "labor division" in pollination in which one type of stamens attracts pollina-tors and satisfies their demand for pollen as food and the other satisfies the plant's need for safe gamete dispersal. The extent and patterns of stamen differentiation differ notably among taxa with heterantherous flowers. Seven species with heteromorphic stamens in three genera were sampled from Leguminosae and Melastomataceae, and the morphological difference of androecia, pollen content, pollen histochemistry and viability, pollen micro-morphology, as well as the main pollinators were examined and compared. Pollen number differs significantly between stamen sets of the same flower in most species investigated, and a correlation of pollen number and anther size was substantiated. Higher pollen viabilities were found in the long (pollinating) stamens of Senna alata (L.) Roxb. and S. bicapsularis (L.) Roxb. Dimorphic pollen exine ornamentation is reported here for the first time in Fordiophytonfaberi Stapf. The height of stigma and anther tips of the long stamens in natural conditions was proved to be highly correlated, supporting the hypothesis that they contact similar areas of the pollinator's body.