239 



all diseases and insect injury. The leaves appear late but they do not 

 fall until the first killing frost when thej^ are killed, and frequently 

 practically all of the leaves will fall in one day. The staminate flowers 

 exhale a fetid odor for a few days which is about the only objectionable 

 feature in this tree. In order to obviate this objection, nurserymen are 

 now offering for sale pistillate trees which have been grafted on com- 

 mon stock. 



ACERACEAE. The Maple Family. 



ACER. The IMaples. 



Trees with terete branches; scaly buds; long petioled, opposite 

 leaves; fruit consists of two long-winged samaras which are joined at 

 their base, separating at maturity. The sap of some of the species, 

 when concentrated, yie'ds the maple sugar and sirup of commerce. 



Leaves trifoliate or pinnate 1 A. Negundo. 



Ijeaves simple. 



Winter bnds blunt; flowers appear from lateral Inids before 

 the leaves ; fruit maturing in the spring or earljr summer. 

 Leaves entirely glabrous beneath at maturity, .5-lobed; the 

 two sinuses between the three largest lobes generalljf 

 somewhat closed, formed as it were by the arcs of two 

 circles which meet to form the sinus, and which if 

 they were extended outward would cross each other 

 within a few dm. of the sinus; fruit more or less 



pubescent at maturity 2 A. saocharinum . 



Leaves are never all entirely glabrous at maturity, 3-5 



lobed; the two largest sinuses are geuerallj' angular 



with straight sides which if e.xtended outward would 



never cross; fruit smooth at maturitj'. 



Twigs smooth at maturity; leaves at maturity smooth 



beneath e.xoept a few hairs in the axils of the veins, 



or more rarely the entire lower siu'face covered 



more or less -ndth a short pubescence; mature fruit 



generally 2-3. .5 cm. long 3 A. rubrum. 



Twigs more or less pubescent at maturity; leaves 

 beneath covered with a dense tomentum which 

 remains until maturitjf or sometimes becoming 



scanty; fruit about 4-.5 em. long var. Drummondii. 



Winter buds acute, sometimes somewhat blunt; flowers 

 appear from terminal buds after the leaves; fruit matur- 

 ing in the autumn. 

 Leaves yellow green beneath; base of the petiole of the 

 terminal leaves enlarged at the base, smooth or 

 somewhat pubescent about the enlarged base 4 A. nigrum. 



