莼菜花的形态解剖

The Morphology and Anatomy of The Flower in Brasenia Schrebei Gmel

莼菜的花单朵着生于长柄上,花柄内有3-4束维管束.花下位,萼片3枚,花瓣3枚,结构相似,上下表皮均具一层细胞,薄壁基本组织层次较厚密,其间分布有维管束.雄蕊多数,花丝不成瓣状而呈长丝状,花药内向,每一雄蕊具1条维管束.雌蕊群由6-12枚分离心皮组成,排成2-3轮.每一心皮具1长柱头.在心皮整个发育期间,其腹面仍留有裂缝,倒生胚珠2枚,有时为1枚,着生于心皮背面的中央.根据形态和解剖的观察,我们认为莼菜属及Cabomba 亲缘密切,可独立为莼菜科.它较广义的睡莲科中具合生心皮的各属为原始.另方面莼菜属具下垂倒生,两层珠被、厚珠心的胚珠,维管束中有原生木质部空腔.这些事实表明,莼菜属与睡莲科的其它属亦有联系.故把它们(除莲属)归入睡莲目是恰当的.

The solitary flower is attached to a long pedicel.There are three to four strands of vascular bundles in the pedicel.The folwer is hypogynous it has three sepals and three petals which structures are very similar.They have a single-layered epidermis on both sides and a relatively thick compact ground tissue of parenchyma in which numerous vascular bundles are located.Stamens are numerous,which fila- ments are not petal-like but long and filiform.The anthers are introse.Each stamen receives a single vascular bundle.The gynecium consiste of two or three whorls of 6-12 apocarpous carpels.Each carpel has a long stigma.An opening remains at ventral part of each carpel throughout its development.The two,or sometimes one, anatropus ovles are attached at the center of the dorsal side of the carpel. Form floral morphological and anatomical observations we suggest that Brassnia and Cabomba are closely related,they may be form a distinct family Cabombaceae. It is more primitive than those of the syncarpous genera of Nymphaeaccac(Sensu Late).On the other hand,The Brasenia has pendulous anatropous,two integuments,crassinucellate ovule and the vaseular bundles possess proxylem.These facts indicate that the Brasenia is related to other Nymphaeaceous genera.It is advi- sable to put them in the same order-Nymphaeales excep for Nelumbo.