The elements of botany for beginners and for schools . l curve and coil prompt-ly after one or two light strokesby the hand. 474. Among spontaneous move-ments the most singular are thoseof Desmodium gyrans of India,sometimes called Telegraph-plant,which is cultivated on account ofthis action. Of its three leaflets,the larger (terminal) one movesonly by drooping at nightfall andrising with the dawn. But its twosmall lateral leaflets, when in acongenial high temperature, by dayand by night move upward anddownward in a saccession of jerks,stopping occasionally, as if to re-cover from exhaustion.
The elements of botany for beginners and for schools . l curve and coil prompt-ly after one or two light strokesby the hand. 474. Among spontaneous move-ments the most singular are thoseof Desmodium gyrans of India,sometimes called Telegraph-plant,which is cultivated on account ofthis action. Of its three leaflets,the larger (terminal) one movesonly by drooping at nightfall andrising with the dawn. But its twosmall lateral leaflets, when in acongenial high temperature, by dayand by night move upward anddownward in a saccession of jerks,stopping occasionally, as if to re-cover from exhaustion. In mostplant-movements some obviouslyuseful purpose is subserved: thisof Desmodium gyrans is a riddle. 475. Movements in Flowers are very various. The most remarkableare in some way connected vvitli fertilization (Sect. Xlll.). Some occurunder irritation: the stamens of Barberry start forward when touched attlie base inside: those of many polyandrous flowers (of Sparmannia verystrikingly) spread outwardly wlien lightly bruslied: the two lips or lobes. Fig. 491. Portion of stem and leaves of Telegraph-plant (Desmodium gyrans),almost of natur^ siz^i 154 VEGETABLE LIFE AND WORK. [SECTION 16. of the stigma in Mimulus close after a Some are automatic andare connected with dichogamy (339): the style of Sabbatia and of large-flowered species of Bpilobinm bends over strongly to one side or turns down-ward when the blossom opens, but slowly erects itself a day or two later. 476. Extraordinary Movements connected, with Capture of In-sects. The most strilcing cases are those of Drosera and Dionsea; for anaccount of which see How Plants Behave, and Goodales PhysiologicalBotany. 477. The upper face of the leaves of the common species of Drosera,or Sundew, is beset with stout bristles, having a glandular tip. This tipsecretes a drop of a clear but very viscid liquid, which glistens like a dew-drop in the sun; whence the popular name. When a fly or other smallinsect, attracted by the
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1887
