504 ON SEEDLINGS 



Cotyledons oblong-obovate, minutely emarginate, finely pubes- 

 cent, light green with reddish petioles, pinnatinerved like the leaves. 



Stem erect, terete, herbaceous, finely pubescent ; 1st internode 

 3-7 mm. long. 



First leaves simple, cauline, opposite, oblong, obtuse, dentate- 

 serrate, petiolate, stipulate, finely pubescent, light green, pinnati- 

 nerved. 



PLATANACE.E. 



Benth. et Hook. Gen. PL iii. 396. 



Fruit and Seed. The ovary is linear, one-celled and one- 

 ovuled with the wall greatly thickened on one side. The ovule is 

 (solitary, rarely are there two, one of which becomes aborted, 

 pendulous from the apex of the cavity and orthotropous. This 

 arrangement is very rare, as in dicotyledonous plants the ovule 

 when single and orthotropous is in almost all other cases 

 erect, the result of which seems to be to facilitate the easy 

 access of the pollen-tube to the micropyle. The achenes are 

 linear, surrounded at the base by long brown hairs, greatly 

 thickened or clubbed in the upper part, and surmounted 

 obliquely or on one side by the persistent remains of the 

 style. The seed is solitary, pendulous, and linear with a 

 membranous testa. Endosperm is usually present in small 

 quantity surrounding the embryo, but is said to be some- 

 times absent. The embryo completely fills the remainder of 

 the cavity, and is straight and linear. The cotyledons are 

 plano-convex, very little wider than the inferior radicle and 

 about equal to it in length or slightly longer. They gene- 

 rally lie in the broader plane of the seed with their edges 

 towards the thickened portion, but are sometimes oblique 

 to it. 



The Order is represented by the single genus Platanus, con- 

 sisting of five to six species. The above characters are well 

 seen in longitudinal and transverse sections of the achene of 

 a species of Platanus, probably P. orientalis (fig. 652). 



Seedlings. The seedling of P. orientalis (fig. 653) is com- 

 paratively small in conformity with the seed, but rapidly gains 



