Anatomy and Ultrastructure of Wolffia columbiana and Wolffia borealis, Two Nonvascular Aquatic Angiosperms

摘要: Light and electron microscope studies of Wolffia columbiana Karsten borealis (Engelmann ex Hegelmaier) Landolt & O. Wildi vegetative stages were undertaken. Asexual reproduction in both species involves the budding daughter fronds from a meristematic region reproductive pouch mother frond. A single plant (mother plus granddaughter fronds) is composed six to seven individuals at various developmental stages. The mesophyll W. (especially older thin-walled cells with few organelles; chloroplasts are concentrated instead epidermis have normal ultrastructure consisting appressed unappressed thylakoids. Anticlinal cell walls adjacent epidermal elaborate wall ingrowths characteristic transfer cells. vary size small toward dorsum large ventrum. Chloroplasts dorsal...