MAPLE FAMILY 



Stamens. Three to seven, hypogynous ; filaments long and slen- 

 der in the sterile flowers, short in the fertile. Anthers reddish, ob- 

 long, two-celled ; cells opening longitudinally. 



Pistils. In sterile flowers rudimentary ; in fertile, ovary borne on 

 narrow disk, superior, downy, tvvo-lobed, two-celled, compressed 

 contrary to the dissepiment, wing-margined ; styles two, united at 

 base only, long, exserted, red ; ovules two in each cell, one usually 

 aborts. 



Fruit. Two samaras united forming a maple key. Borne on 

 slender drooping pedicels an inch and a half to three inches long. 

 Vary in length from one and one-half to three inches. Wings di- 

 vergent, straight or curved, three-fourths of an inch broad, deep 



Staminate and Pistillate Flowers of Silver Maple, <Acer saccharinum. 



red or pale chestnut brown. Seed reddish brown. April, May. 

 Cotyledons thin, leaf-like. Seed germinates as soon as it falls to 

 the ground. 



The seed of Acer usually ripens in the autumn and germinates the fol- 

 lowing spring. The seed of the two American species with precocious flowers, 

 A. rubrum and A. Saccharinum, however, ripens at the end of a few weeks after 

 the trees flower, and germinates at once. This is a provision, perhaps, acquired 

 by these species to insure their perpetuation ; they grow in low, wet land, often 

 inundated during the winter, and the seed, if it ripened in the autumn would 

 often lie in the water through the winter and be in danger of losing its vitality ; 

 but it reaches the ground after the water has fallen in the swamps and before 

 the exposed surface of the ground has become baked by the hot sun of summer, 

 that is, when it is just in the condition to insure the germination of seed. 



CHARLES S. SARGENT. 



74 



