关键词: 苏铁属, 花粉形态

Abstract: The pollen morphology of the genus Cycas from China has been investigated under LM and SEM. The pollen grains are of medium size, with polar axis 26.5-35.7 /^m, and equatorial ax-is 20.6- 26.4 fim in length. In shape they are elliptic or circular on AMB, and boat- or kidney-shaped on equatorial contour, with a single deep and longitudinal furrow reaching from end to end on distal face. The opening or closure of the furrows and pollen shape change when th grains are dry or moistened. The inner surface of the furrows are ofter wringled with strips. The distal surface are smooth or rarely minutely warty while on the opposite face it is perforate of foveolate. The interspecific differences are very obscure, implying a natural group of Cycas. The genus Cycas is similar to other genera ofcycads in pollen morphology. Similar pollen type is found only in the genus Ginkgo. Their pollen resemblence implys that their relationship is possibly closer than cycads with other extant taxa of gymnosperms.

Key words: Cycas