OP THE SEED-VESSEL AND ITS KINDS. 277 



an essential part, the seeds being frequently 

 naked, and guarded only by the calyx, as 

 in the first order of the Linnsean class 

 Didy?iamia 9 of which Lamium, Engl.Bot. 

 t. 768, and Galeopsis, t, 667? are exam- 

 ples ; also in the great class of compound 

 flowers, Syngenesia, as well as in liumex, 

 t. 724, Polygonum, t. 989, the Umbelli- 

 ferous tribe, numerous Grasses, &c. 



The use of the Seed-vessel is to protect 

 the seeds till ripe, and then in some way 

 or other to promote their dispersion, either 

 scattering them by its elastic power, or 

 serving for the food of animals in whose 

 dung the seeds vegetate, or promoting the 

 same end by various other means. The 

 same organ which remains closed so long 

 as it is juicy or moist, splits and flies 

 asunder when dry, thus scattering the 

 seeds in weather most favourable for their 

 success. By an extraordinary provision of 

 Nature, however, in some annual species of 

 Mesembrypithemum, natives of sandy de- 

 serts in Africa, the seed-vessel opens only 

 in rainy weather; otherwise the seeds 

 might, in that country, lie long exposed 



