LEGOIIXOS.E 385 



laterally compressed, unequally auricled at the base. The 

 cotyledons are oblong, plano-convex, and unequal-sided, owing 

 to the basal notch of the seed ; the radicle is bent at right angles 

 to the cotyledons along the basal edge of which it lies, and 

 then projects beyond them into the smaller auricle of the seed, 

 where it becomes embedded in a thickened portion of the testa 

 at the micropyle. 



Seeds containing endosperm may be subdivided into those 

 having a curved or bent radicle, and those having an entirely 

 straight embryo. The first is represented by Laburnum 

 vulgare (fig. 266), Sesbania segyptiaca, and Kennedya rubi- 

 cunda. The cotyledons of all are unequal at the base owing 

 to the position of the radicle, and indented at the sides owing 

 to a thickening at the hilum. All three belong to the suborder 

 Papilionacege, and have a small quantity of endosperm, except 

 in the case of Sesbania aegyptiaca (fig. 276), where there is a 

 considerable quantity on the backs of the cotyledons, which 

 are therefore thin. A remarkable exception occurs in Scor- 

 piurus sulcata, and other species, in which the embryo is 

 variously twisted and narrow, with the intervening spaces 

 occupied by endosperm. 



The seeds having a straight embryo belong to the suborder 

 Csesalpmiese. The radicle is slightly bent or curved in Cassia 

 Sophora, and accurnbent, thus forming a transition state be- 

 tween this and the last subgroup. A good type of the sub- 

 group is shown in Cassia Fistula (fig. 301) . The cotyledons 

 are here more or less twisted. The outer coat of the seed 

 becomes separated from the rest, forming a broad, white, 

 torn band down the middle of both surfaces. Cassia Absus 

 and Cercis Siliquastrum have orbicular cotyledons, notched 

 at the base to accommodate the radicle. Cassia obovata is 

 remarkable for the small size of its embryo, which may 

 be due to the fact that the seeds are ruminated to a con- 

 siderable depth from the periphery. The cotyledons are 

 orbicular. In all the species of Cassia mentioned the endo- 

 sperm is rather copious and cartilaginous or horny when 

 dry. 



Seedlings. The prevailing type of cotyledons throughout 

 the Order is oblong ; but there are several important modifica- 



c c 



