中国泽泻科四属的花部综合特征及对传粉方式的适应性

The Floral Syndromes Adapted to Pollination Patterns of Four Genera in Alismataceae from China

对泽泻科中国产 4属 8种的花部综合特征的研究表明 :长喙毛茛泽泻 ( Ranalisma rostratum Stapf)、东方泽泻 [Alisma orientale( Samuel.) Juz.]、窄叶泽泻 ( A.canaliculatum A.Braun et Bouche.)具有相对平滑的花粉粒及柱头表面、较低的花粉 -胚珠比 ( P/O)和不发达的分泌结构 ,这些特征不大适合风媒或虫媒传粉而可能与其花前期闭花授粉 (后二种亦有虫媒传粉 )有关 .小慈姑 ( Sagittaria potamogetifolia Merr.)、矮慈姑 ( S.pygmaeaMiq.)和野慈姑 ( S.trifolia L inn.)的花部特征包括具刺状纹饰的花粉外壁、指状的柱头突起、相对较高的 P/O比和较发达的花内分泌细胞 ,适应于风媒与虫媒兼性传粉方式 ,更倾向于虫媒传粉 ,而同属的冠果草 [S.guyanensisH.B.K.ssp.lappula( D.Don) Bojin]已适应于花前期闭花授粉而只有甚低的 P/O比 .尽管泽苔草 [Caldesiaparnassifolia( Bassi ex L inn.) Parl.]光滑的柱头和花粉粒对虫媒或风媒传粉皆缺乏适应性 ,但该种的 P/O比在所观察到的各种中却是最高的 ,这暗示它仍应是异花传粉的 .

In 4 genera of Alismataceae from China, floral syndromes related to the pollination mechanisms of 8 species were observed. Floral syndromes of some pre-anthesis cleistogamous species such as Ranalisma rostratum Stapf, Alisma orientale (Samuel.) Juz., A. canaliculatum A. Braun et Bouche., including considerably smooth surfaces of pollen grains and stigmas, relatively low values of pollen-ovule ratios (P/O), and undeveloped glandular cells in flowers, could not suit to wind/insect pollination. But in species of Alisma, inter-flower pollination by insects after flowers opening was discovered. Syndromes of Sagittaria potamogetifolia Merr., S. pygmaea Miq., and S. trifolia Linn., including spinesent exines of pollen grains, finger-shaped stigmatic papillas, relatively high values of pollen-ovule ratios and well-developed glandular cell in flowers, adapted to wind/insect pollination but tended to anemophily, while S. guyanensis H. B. K. ssp. lappula (D. Don) Bojin is pre-anthesis cleistogamous with remarkably low value of pollen ovule ratio. The smooth pollen grains and stigmas of Caldesia parnassifolia (Bassi ex Linn.) Parl. are unsuitable for anemophilous/entomophilous pollination, inter-flower pollination by insects of this species is indicated by the highest pollen-ovule ratio in the studied species of Alismataceae and was verified by field observation.