The structure & development of the mosses and ferns (Archegoniatae) . hy\ Fig. 194.—a, Pinnule of Aspidmm spiniilosuin (Schw.), showing the sori (s) with kidney-shapedindusium, X4; B, cross-section of a pinna from a young sporophyll of Onoclea struthioj/teris;s, sorus, X40. venation of the leaves and the position of the sporangia. Theleaves range from the undivided ones of Vittaria or Scolopen-drium to the repeatedly divided leaves, usually pinnate, of suchforms as Pteris Aqtdlina. In some tropical epiphytic species, such as Asplenium nidus, Platy-cerium, species of Polypodiuin, theleaves are
The structure & development of the mosses and ferns (Archegoniatae) . hy\ Fig. 194.—a, Pinnule of Aspidmm spiniilosuin (Schw.), showing the sori (s) with kidney-shapedindusium, X4; B, cross-section of a pinna from a young sporophyll of Onoclea struthioj/teris;s, sorus, X40. venation of the leaves and the position of the sporangia. Theleaves range from the undivided ones of Vittaria or Scolopen-drium to the repeatedly divided leaves, usually pinnate, of suchforms as Pteris Aqtdlina. In some tropical epiphytic species, such as Asplenium nidus, Platy-cerium, species of Polypodiuin, theleaves are arranged so that theyform receptacles for collectinghumus. In the two latter generathese leaves are very much modi-fied, the two forms of leaves beingfamiliar to all botanists in thecommon Platycerimn alcicorne,where the closely overlappinground basal ones are very highlydeveloped.^ The sporangia may almostcompletely cover the backs ofthe sporophylls, as in Platy-ceriuin, or more commonly formdefinite sori, which may or may not have an indusium. Where -^ Goebel,
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Keywords: ., bookcentury1800, bookdecade1890, bookidstructuredev, bookyear1895
