Organography of plants, especially of the archegoniatae and spermaphyta . mple. The chief shoots havea radial arrangement of the leaves, and each of the leaves grows out at itsbase over the point of attachment. It is thus somewhat peltate. The bluntbasal continuation standing out from the surface of the shoot serves asa hook for climbing, although not a very complete one. The formation ofthe leaves conforms in all essentials with what we have seen in Asparaguscomorensis (Fig. 215). The branches of higher order do not form thesehooks and climb ; they are dorsiventral shoots like those of Lycopo
Organography of plants, especially of the archegoniatae and spermaphyta . mple. The chief shoots havea radial arrangement of the leaves, and each of the leaves grows out at itsbase over the point of attachment. It is thus somewhat peltate. The bluntbasal continuation standing out from the surface of the shoot serves asa hook for climbing, although not a very complete one. The formation ofthe leaves conforms in all essentials with what we have seen in Asparaguscomorensis (Fig. 215). The branches of higher order do not form thesehooks and climb ; they are dorsiventral shoots like those of Lycopodiumcomplanatum ^ * See Part I, p. e 2 42 o TRANSFORMED LEAVES B. DiCOTYLEDONES. Stylidium scandens. Stylidium scandens climbs by means of leaveswith hook-like ends. Pereskia. Many species of Pereskia develop single thorn-leaves ashooks for climbing. Quisqualis indica. The features of Quisqualis indica have alreadybeen referred to-^. Upon the long shoots the stalks of well-developed foliage-leaves, whose lamina has functioned as a leaf, are transformed into hooks. Fig. 283. Bignonia albo-lutea. Portion of shoot. The two lower leaves are ternate, the two upper have a trifidtendril instead of the end leaflet. After A. Mann. which remain after the lamina has fallen, and thus offer an instructiveexample of seasonal change of function. Other Dicotyledones show a transition from formation of hooks toformation of tendrils : the lamina, which forms a curved hook, serves as ananchoring-organ, whilst the stalk is a tendril. Bignonia. Many Bignoniaceae have strong claw-hooks, for exampleBignonia unguis. These are less developed in, for example Bignonia albo-latea (Figs. 283, 284), where the history of development, as in Cobaea,shows that the hooks proceed from the lamina which is in a rudimentarycondition visible on young tendrils (Fig. 284). C. MONOCOTYLEDONES. Asparagus comorensis. The climbing-hooks of Asparagus comorensis,formed from the under portion of the peltate leaves, have
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