Organography of plants, especially of the archegoniatae and spermaphyta . er-plantsof most different cycles of affinity, whether itarise by branching, as is usual, or by the formationof holes, as in Ouvirandra ^, has clearly a relation-ship to the conditions of life, just as have the gillsin animals. The long drawn-out tips of the leavesof many plants which grow in wet regions serve asdrip-tips -, and are therefore adapted to the rapiddrying of the leaf-surface. On the other hand, wefind that many forms of leaves appear through variation and stand only in very indirect rela-tionship , and cann
Organography of plants, especially of the archegoniatae and spermaphyta . er-plantsof most different cycles of affinity, whether itarise by branching, as is usual, or by the formationof holes, as in Ouvirandra ^, has clearly a relation-ship to the conditions of life, just as have the gillsin animals. The long drawn-out tips of the leavesof many plants which grow in wet regions serve asdrip-tips -, and are therefore adapted to the rapiddrying of the leaf-surface. On the other hand, wefind that many forms of leaves appear through variation and stand only in very indirect rela-tionship , and cannot at any rate be regarded as direct adaptations, to environment ^. The fern-leaved varieties of beechand other plants and the remarkable crested and other so-called mon-strous leaves in ferns are of this character (Fig. 225). In these circumstances it will be more satisfactory in dealing with thispart of the subject if a few examples be described, drawn from plants inwhich the configuration of the/^/m^^-/mt/^j is strikingly different at differentperiods of their Fig. 225. PoI}-podium vulg^ which, in some pinnules,shows more copious branching thanusual. ^ See Goebel, Pflanzenbiologische Schilderungen, ii (1893), p. 320. Jungner, Anpassungen dor Pflanzcn an das Klima in den Gegenden der regenreiclicn Kamerun-gebirge, in Botanischcs Centralblatt, xlvii (1S91), p. 353; Stahl, Regenfall und Blattgestalt, inAnnales du Jardin botanique de Bnitenzorg, xi (1S93), p. 100. See Goebel, op. cit., ii (1S93), p. 320, where I show that the Podostemaceae may underlike external conditions exhibit manifold relationships of configuration. See also Goebel. op. (1889), Introduction ; id., Uber Studium und Auffassung der Anpassungserscheinungen bei Pflanzen,Akademie-Rede, Miinchen, 1S9S. * See Part I, p. 1S5. 346 CONFIGURATION OF LEAF AND ENVIRONMENT (i) PTERIDOFHYTA. Where the configuration of the leaf is so simple, as it is in the Lyco-podineae and Equisetaceae ^, it is hardl
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