United States or Israel ? Vote for the TOP Country of the Week !
The extremity being lightly rubbed on the concave surface, became just perceptibly curved in 7 m., distinctly in 10 m., and hooked in 20 m. We have seen that the tendrils in the last three families, namely, the Vitaceae, Sapindaceae and Passifloraceae, are modified flower- peduncles. In two or three species of Modecca, one of the Papayaceae, the tendrils, as I hear from Prof.
In Zanonia Indica, which belongs to a different tribe of the family, the forked tendrils and the internodes revolve in periods between 2 hrs. 8 m. and 3 hrs. 35 m., moving against the sun. VITACEAE. In this family and in the two following, namely, the Sapindaceae and Passifloraceae, the tendrils are modified flower- peduncles; and are therefore axial in their nature.
The species to be described belong to ten families, and will be given in the following order: Bignoniaceae, Polemoniaceae, Leguminosae, Compositae, Smilaceae, Fumariaceae, Cucurbitaceae, Vitaceae, Sapindaceae, Passifloraceae. BIGNONIACEAE. This family contains many tendril-bearers, some twiners, and some root-climbers. The tendrils always consist of modified leaves.
Tendril-bearers have undergone much more modification than leaf-climbers; hence it is not surprising that their supposed primordial habits of revolving and twining have been more frequently lost or modified than in the case of leaf-climbers. The three great tendril-bearing families in which this loss has occurred in the most marked manner, are the Cucurbitaceae, Passifloraceae, and Vitaceae.
It is a singular fact that three families, so widely distinct as the Bignoniaceae, Vitaceae, and Cucurbitaceae, should possess species with tendrils having this remarkable power. Sachs attributes all the movements of tendrils to rapid growth on the side opposite to that which becomes concave.
Again, the tendrils of some few plants never contract spirally unless they have first seized hold of some object; if they catch nothing they hang down, remaining straight, until they wither and drop off: this is the case with the tendrils of Bignonia, which consist of modified leaves, and with those of three genera of the Vitaceae, which are modified flower-peduncles.
This genus, belonging to the same family of the Vitaceae, produces well- developed tendrils and ordinary bunches of flowers; but there are no gradations between the two states.
Word Of The Day