Organography of plants, especially of the archegoniatae and spermaphyta . it was firsttraced in Cobaea scandens ^. The efiec-tive tendrils of this plant are formedout of the end-portion of the pinnateleaves. The tendril-branches are attheir end provided with small curvedclaws, by means of which the shoot ofCobaea is able to climb for great dis-tances over tree-stems, rocks, and likeobjects. The history of development (seeFigs. 286, 287) shows that these claws,which are very small, are vestiges ofreduced or transformed laminae of leaf-lets, and the tendrils are the development o
Organography of plants, especially of the archegoniatae and spermaphyta . it was firsttraced in Cobaea scandens ^. The efiec-tive tendrils of this plant are formedout of the end-portion of the pinnateleaves. The tendril-branches are attheir end provided with small curvedclaws, by means of which the shoot ofCobaea is able to climb for great dis-tances over tree-stems, rocks, and likeobjects. The history of development (seeFigs. 286, 287) shows that these claws,which are very small, are vestiges ofreduced or transformed laminae of leaf-lets, and the tendrils are the development of the arms of thetendrils entirely conforms to that ofthe leaflets in the earliest stages, onlyin the formation of the tendrils in theupper part of the leaf a richer branch-ing sets in, and the laminar primordia ofthe leaflets is arrested very early. Thesame thing is seen in species of Bignonia(Figs. 283, 284) and of tendrils do not, however, in all cases proceed from leaf-stalks or the stalks of leaflets. They may be formed by the early elongation of. Fig. 285. Desmoncus sp. Leaf. Transitionof leaf-pinnules into hooks. Much reduced. •^ See Goebel, Vergleichende Entwicklungsgeschichte der Pflanzenorgane, in Schenks Handbuchder Botanik, iii (1884), p. 431; A. Mann, Was bedeutet Metamorphose in der Botanik? , Miinchen, 1894. TENDRILS OF CUCURBIT ACEAE 423 the primordium of the whole leaf, or of a portion of a leaf, and then theinception of a blade may no longer be visible. This is what takes place, sofar as my investigations extend, in the Leguminosae, Cucurbitaceae, andTropa6olum tricolorum ^ In the Leguminosae, as in other cases, it is theend of the leaf which is transformed into the tendril ^ and in Pisum the prim-ordium of a tendril may be caused to develop partially as a foliage-leaf(Fig. 289) ^ by separation of all other leaves and leaflets of the plant, andthis is in correspondence with what has been said above * in regard to thebehavi
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