Abstract

Light and electron microscopic studies were undertaken on the flower structure and anther dehiscence of Wolffia arrhiza L. The anthesis is protogynous. The pistil and the stamen were located in dorsal flower cavity and the pistil protrude first. The inner structure of the pistil and the stamen described with special notes on the anther dehiscence line and the septal cells. The pistil is comprised of a concave stigma, a style and a unilocular ovary with one orthotropous ovule. The bitegumic ovule is covered with a secretary substance within the ovary. The stamen has a filament and bilobed monothecous anther. The tannin body in the stomial cells as well as stigma and style may act as a deterrent. Meanwhile, the uneven thickening of the septal walls and the massive central vacuole of the septal cells probably aid the dehiscence of the anther sac.

中文摘要

應用光學及電子顯微鏡檢觀察無根萍之花的內部構造與花藥開裂。無根萍於葉狀體背部花腔內先後分別長出雌蕊和雄蕊，通常為雌先熟。除就雌蕊和雄蕊內部構造詳加描述外，特別探討花藥開裂線及藥隔之細胞特性。開裂線上的口邊細胞、柱頭及花柱細胞內富含單寧，可能具保護防禦功能。藥隔之細胞其細胞壁加厚不均勻且具大型液胞，此等特性與花藥內壁纖維質增厚可能共同促成花藥之開裂。

Keyword: Flower structure, Lemnaceae, Stomia, Wolffia.