The structure & development of the mosses and ferns (Archegoniatae) . e Marattiaceae alone, among theother Ferns, show this great variability. Trichomes occur, but not so abundantly as in most of theLeptosporangiatae. They have mostly the form of hairs, whichare either (those formed on the margins of the youngleaves) oP persistent for a longer time, like those that cover theend of the stem apex and bases of the petioles in manyspecies. TJie Sporangium All of the Hymenophyllaceae agree closely in the position ofthe sporangia, whose development has, however, been studiedonly in TricJi
The structure & development of the mosses and ferns (Archegoniatae) . e Marattiaceae alone, among theother Ferns, show this great variability. Trichomes occur, but not so abundantly as in most of theLeptosporangiatae. They have mostly the form of hairs, whichare either (those formed on the margins of the youngleaves) oP persistent for a longer time, like those that cover theend of the stem apex and bases of the petioles in manyspecies. TJie Sporangium All of the Hymenophyllaceae agree closely in the position ofthe sporangia, whose development has, however, been studiedonly in TricJiomanes; but from the close correspondence in 1 Prantl (i), p. 26. - Bower (11), p. 30S. 3 Prantl (i). ^ Prantl, 368 MOSSES AND FERNS CHAP. other respects it is not likely that HyinenopJiylluni differs essen-tially from the latter. The sorus occupies the free end of a vein,which often continues to grow for a long time in Trichomanes,and forms a long slender placenta or columella, upon which thesporangia arise basipetally. While the receptacle is still very sp--. E.
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Keywords: ., bookcentury1800, bookdecade1890, bookidstructuredev, bookyear1895
