STERCULIACE^E 265 



and brittle, resembling bark ; the raphe ventral, composed of 

 tough fibres, separable from the seed, and extending from near 

 the apex to the base of the cavity of the nut ; micropyle 

 superior; endosperm absent. Embryo straight, very large 

 and fleshy, filling the seed, pale pink or flesh-coloured. 

 Cotyledons thick, plano-convex, sometimes slightly wrinkled, 

 frequently if not always unequal, broadly oblong-oval in outline, 

 auricled at the base and embracing the radicle. The largest one 

 is sometimes placed with its back to the ventral, sometimes to 

 the dorsal suture, or irregularly. The embryo is frequently 

 abnormal, assuming various shapes, while the cotyledons are 

 of different lengths, variously twisted and deformed, or they 

 may even be deeply lobed, divided or multiplied, and irregular 

 in size and number. The radicle when normal is short, stout, 

 and grasped by the auricles of the cotyledons, beyond which it 

 does not protrude. The plumule is small and densely covered 

 with short, brown hairs. 



The species of Cola and Herrania agree with Heritiera in 

 having exalbuminous seeds and thick cotyledons, but the 

 radicle is close to the hilum. Myrodia has exalbuminous seeds 

 and unequal, conferrurninate or amalgamated cotyledons, the 

 larger including or partly enclosing the smaller one. 



A third type is presented by Eeevesia, in which the seeds 

 have a fleshy endosperm, a straight embryo, and flat foliaceous 

 cotyledons. The seeds are also laterally fixed and produced 

 into a wing on the back. Physodium and Abroma have also a 

 straight embryo, broad, flat, cordate cotyledons, and albuminous 

 seeds ; flat, foliaceous cotyledons, and a straight embryo, also 

 occur in Melochia, Dicarpidium, Waltheria, Eulingia, Com- 

 mersonia, Seringia, Thomasia, Guichenotia, and Lasiopetalum, 

 but the embryo varies considerably in shape both before and 

 after germination. 



A fourth type, having exalbuminous seeds and spirally 

 convolute cotyledons, is presented byKleinhoviaand Buettneria, 

 the cotyledons being folded round the radicle, at any rate in 

 the latter. Slightly different from this are those seeds having 

 a thin layer of endosperm, which is even altogether absent in 

 all the species of Helicteres, Eriolsena, and Ayenia. The coty- 

 ledons also vary in being convolute or contorted and plicate. 



