266 MANUAL OF BOTANY 



Shot (Canna) and Paeony a.lso somewhat black, in the Arnatto 

 and Barricarri (Adenanthera) red, in French Beans and the 

 seeds of the Castor-oil plant beautifully mottled, and various 

 other tints may be observed in the seeds of different plants. 



The testa also varies in texture, being either of a soft nature, 

 or deshy and succulent, or more or less spongy, or membranous 

 or coriaceous, or, when the interior of its cell-walls is much 

 thickened, it assumes various degrees of hardness, and may 

 become woody, crustaceous, &c. 



The siu:face of the testa also presents various appearances, 

 and is often furnished with different appendages. It may 

 be smooth, as in Adenanthera ; or wrinkled, as in Nigella, ; 

 striated, as in Tobacco ; marked with ridges and furrows, as 

 in Delphinium {fig. 579) ; netted, as in Nasturtium {fig. 578) ; 

 alveolate or pitted, as in the Poppy ; tuberculated, as in the 



Fig. 578. Fig. 579. FiG. 580. 



Fi(/. 578. Rounded seed of the Watercress {Naslurthim officinale). The testa 



is reticulated or netted. Fig. 579. Obovoid seed of the Larkspur {^Del- 



phinium), the testa of which is marked with ridges nnd furrows. Fiij. 



580. Seed of Oliickweed (SteUaria). the testa of which is tuberculated. 



Chiekweed {fig. 580) ; spiny, as in the Mulberry, &e. The 

 testa of some seeds is also furnished with hairs, which may 

 either cover the entire surface, as in the various species of 

 Gossypium, where they constitute the material of so much value 

 called Cotton, and in the Silli-cotton tree {Bomiax) ; or they 

 may be confined to certain points of the surface, as in the 

 Willow, Asclepias {fig. 582), and Epilohiwin {fig. 587). In the 

 latter cases the tufts of hairs, thus confined to certain points of 

 the testa, constitute what is called & coma, and the seed is said 

 to be comose. 



Other seeds, again, have winged appendages of various 

 kinds ; thus, in the Sandwort {fig. 581), the testa is prolonged, 

 so as to form a flattened margin to the seed, which is then de- 

 scribed as marginate or bordered ; while in the seeds of Catalpa, 

 Bignonia, Swietenia, Moringa, &c., the testa forms wings, and 



