PLANTS. 237 



leaves of grasses revive, and renew their verdure in the 

 spring. In lofty mountains, where the summer heats are 

 not sufficient to ripen the seeds, grasses abound which are 

 viviparous, and consequently able to propagate themselves 

 without seed. It is an observation, likewise, which has often 

 been made, that herbivorous animals attach themselves to 

 the leaves of grasses ; and if at liberty in their pastures to 

 range and choose, leave untouched the straws which support 

 the flowers. *= 



The GENERAL properties of vegetable nature, or proper- 

 ties common to large portions of that kingdom, are almost 

 all which the compass of our argument allows us to bring 

 forward. It is impossible to follow plants into their several 

 species. We may be allowed, however, to single out three 

 or four of these species as worthy of a particular notice, 

 either by some singular mechanism, or by some peculiar 

 provision, or by both. 



I. In Dr. Darwin's Botanic Garden, vol. 1, p. 395, note, 

 is the following account of the vallisneria, as it has been ob- 

 served in the river Rhone. " They have roots at the bottom 

 of the Rhone. The flowers of the female 'plant float on the 

 surface of the water, and are furnished with an elastic sjnral 

 stalk, which extends or contracts as the water rises or falls ; 

 this rise or fall, from the torrents which flow into the river, 

 often amounting to many feet in a few hours. The flowers 

 of the male plant are produced under water ; and as soon 

 as the fecundating farina is mature, they separate them- 

 selves from the plant, rise to the surface, and are wafted by 

 the air, or borne by the currents, to the female flowers." 

 Our attention in this narrative will be directed to two 2:)ar- 

 ticulars : first, to the mechanism, the " elastic spiral stalk," 

 which lengthens or contracts itself according as the water 

 rises or falls ; secondly, to the provision which is made for 

 bringing the male flower, which is produced under water, 

 to the female flower, which floats upon the surface. 



* Witliering's Botanical Arrangement, vol. I., p 2S, eilit. 2. 



