慈菇下胚轴毛的形态发育研究

慈菇种子萌发前,下胚轴基部的表皮细胞分化成生毛细胞。当下胚轴穿出种皮约1—2毫米时,生毛细胞的外壁向外突出,形成下胚轴毛。开始时,其顶端膨大,呈分泌毛状,后呈根毛状。下胚轴毛的主要功能是起固着作用。下胚轴毛发育后期,在其保留细胞核的膨大的基部和突起的毛状体之间形成一细胞壁,此时毛状体便开始萎缩脱落。下胚轴毛的基部重新形成完整的表皮细胞。

STUDIES ON THE DEVELOPMENTAL MORPHOLOGY OF HYPOCOTYLAR HAIRS OF SAGITTARIA SAGITTIFOLIA L.

The epidermal cells of the proximal end of hypocotyl of Sagittaria sag-ittifolia L. differentiate into trichoblast before seed germination. When hypocotyl emerges out of the seed coat for 1-2 mm., wall of trichoblast cell projects outward and transforms into hypocotylar hair. The main function of hypocotylar hair is for anchoring the young seedling under water temporarily. In the beginning of hypocotylar hair formation, the tip of the hair enlarges a little, showing the character of a secretory cell. Later on the hair elongates in the form of a root hair. In the later stage of its development, a cell wall is formed between the nucleated expansive portion and the projecting trichome. After the trichome begins to wither and cast off, the basal portion renews a complete epidermal cell.