银缕梅属花形态及其分类学意义

Floral morphology of Shaniodendron (Hamamelidaceae) and its taxonomic significance

以1995年在江苏宜兴发现的一较大银缕梅居群的花为材料，观察确认金缕梅亚科单种属银缕梅属（ShaniodendronM.B.Deng，H．T．WeietX．QWang）的花序为近头状短稳状花序，由4～7朵花组成，花序内轮4～5朵花，两性；外轮1～2朵花，常为雄花，构成雄全同株。花无柄，无花瓣，花喜常合成浅林状，杯缘及杯背早期簇生长硬毛（hirsute），花生于初生苞片腋处，初生苞片卵形或阔卵形。雄蕊不定数，5～15枚，花丝长，直立。与其他无花瓣属植物比较表明，银缕梅属与特产里海南岸的Parrotia形态极为相似，主要区别在于本属花萼合生成浅怀状。银缕梅属花形态特征的阐明，对探讨金缕梅亚科无花瓣类群的系统发育具有重要意义。

Shanindedron M. B. Deng, H. T. Wei et X. Q. Wang, a monotypic apetalous genus in the Hamamelidaceae, is a deciduous shrubby tree, usually reaching a height of 4 ~5 m.It is limited in distrbution to Tianmu Mountain and Dabie Mountain of the eastern China. The inflorescence of Shaniodendron consists of 4 to 7 small, perfect of staminate flowers, arranged in a subcapitate spike. The flowers are andromonoectous.The staminate flowers are usually basal in the spike. Each sessile flower is in the axil of a primary bract, although the arrangement of the upper flowers appears to be in a head.The calyx is usually a shallow capulate tube with an undulate rim, persistent, with irregular tepal lobes, and it bears long dark brown clustered hairs on the rim and distal side. A single cycle of 5 ~ 14 stamens is inserted irregularly on the hypanthium. The dark red, linear-oblong anthers contain four pollen sacs, and dehisce laterally by means of a simple longitudinal slit. The anther connective is produced as a short apiculus. The anthers are subsessible in bud, but strongly exserted at maturity. The erect filaments are over three times as long as the anthers at maturity. There are long dark brown hairs clustered among the filaments. Bisexual fowers contain a 2-carpellate semi-infericr ovary closely surrounded by the hypanthium. The two styles are long, recurved, and with extensive papillate stigmatic surfaces. In comparision with other apetalous genera,Shanindendron is very similar to Parrotia in flord morphology. It is very important to elucidate phylogenetic relationships in Hamamelidoideae.