362 ON SEEDLINGS 



Leaves simple, cauline, opposite, rarely three at the same level 

 and verticillate, exstipulate, petiolate, glabrous except at the very 

 base on the under side ; petioles terete, generally slightly channelled 

 on the upper side when young, ultimately not channelled. 



1st pair ovate, acuminate, cordate, and palmately five-nerved at 

 the base, reticulate, irregularly and obtusely serrate. 



2nd pair palmately five-nerved and lobed or lobulate, irregularly 



FIG. 252. Acer Pseudo-Platanus. Half nat. size. 



and coarsely dentate-serrate ; terminal lobe triangular ovate, obtuse ; 

 middle lobes very broad and short, obtuse ; basal lobes small or 

 merely tooth-like and obtuse. 



3rd pair similar. 



Ultimate leaves large, palmately five-nerved and -lobed, subcor- 

 date at the base ; lobes triangular-ovate, acuminate, obtuse, rather 

 coarsely, irregularly, and distantly serrate ; basal lobes smallest. 



Acer macrophyllum, Pursh. 



Fruit of two, rarely three samaras ; wings ascending, oblong, ob- 

 tuse, asymmetrical or half-elliptic, reticulate, nearly glabrous except 

 on the thickened portion along the lower side, which is covered with 

 adpressed hairs or bristles ; seed-bearing portion of fruit ovoid, densely 

 covered with rigid spreading bristles or spiny hairs, rather tumid. 



Seed nearly horizontal or slightly ascending, short, deep, some- 

 what obovate in vertical section at right angles to the placenta, and 

 triangular in vertical section parallel with the placenta, rather 

 tumid and conforming to the cavity of the fruit, exalbuminous ; 

 tegmen enormously thickened near the hilum, forming an irregularly 

 conical process projecting into the middle of the seed. 



