华中铁角蕨孢子纹饰形成的超微结构观察

利用透射电子显微镜对铁角蕨科(Aspleniaceae)华中铁角蕨(Asplenium sarelii Hook.)孢子及其纹饰的形成过程进行观察。结果表明:①华中铁角蕨孢子囊发育为薄囊蕨型;②孢子外壁表面光滑,远极面的外壁厚约0.8~1.1μm,近极面的外壁厚约1.4~1.8μm;③孢子周壁厚度约4~5μm,染色较外壁深,分为内层和外层;内层紧帖外壁表面,其上具柱状、瘤状或疣状突起;外层向外隆起形成脊状纹饰的轮廓,脊的下方具空腔,脊的顶端具翅;④铁角蕨型与鳞毛蕨型孢子外壁和周壁纹饰的形成过程具有相似性;⑤孢子的成熟度对于孢子形态的研究是至关重要的,只有完全成熟的孢子的表面纹饰才是稳定的。

Ultrastructural Observations on the Formation of Spore Ornamentation in Asplenium sarelii

The formation and development of the spores and their ornamentations of the fern Asplenium sarelii(Aspleniaceae) were studied by means of transmission electron microscope (TEM). The results were as follows: ①The development of the sporangium of A.sarelii belongs to Leptosporangiate-type. ②The exospore is smooth, with a thickness of about 0.8-1.1 μm in the distal surface and 1.4-1.8 μm in the proximal surface. ③The perispore, with a thickness of about 4-5 μm, can be distinguished into an outer perispore and an inner perispore. The inner perispore is closely associated with the outer surface of the exospore. The inner perispore has cylinder, tuberculate, and verrucate projections on the out surface. The outer perispore uplifts and forms the lophate ornamentations. Simultaneously, cavities are formed inside the outer perispore and the fins are formed outside the perispore. ④The formation processes of the exospore and perispore of Asplenium-type spores are similar with that of Dryopteris-type spores. ⑤The maturity degree of the spore during development is a key factor for studying the spore palynology. Only the matured spore possesses stable spore ornamentation.