Studies on Morphology and Affinity of the Parkeriaceae. II. Sporogenesis, Development of the Gametophyte, and Cytology of Ceratopteris thalictroides

Abstract

1. The development and structure of sporangium and gametophyte in Ceratopteris thalictroides (L.) Ad. Brongn. have been described, as well as observations on morphology of the somatic chromosomes and meiotic behavior. 2. Sporangial development agrees with that in the higher ferns. The sporangial initial divides obliquely; the outer initial produces four capsular segments in cyclic order, and then the inner cell gives rise to four tapetal initials in the same sequence. The primary sporogenous cell undergoes successive divisions to produce eight spore mother ceils, while the tapetal initials give rise to eighty tapetal cells in two layers, the inner layer containing sixty-four, the outer sixteen cells. 3. Development of the gametophyte is regular and normal and that of the antheridium and archegonium follows the sequence usual in leptosporangiate ferns except that the formation of the primary cover cell of the archegonium is belated. The gametophyte is devoid of an apical cell and hairs, is normally thin an...