Rhombic-Leaved Alder 



263 



lobed with the lobes toothed, 5 

 to 10 cm. long, mostly rounded 

 or somewhat heart-shaped at 

 the base; the upper surface is 

 bright green and smooth, the 

 lower light green and either 

 smooth or hairy, at least along 

 the veins, which are quite promi- 

 nent; the leaf-stalks vary from i 

 to 2.5 cm. in length; and the 

 thin ovate stipules, which fall 

 away while the leaves are un- 

 folding, are about i cm. long. 

 The catkins of staminate flowers 

 are 2.5 to 4.5 cm. long; each 

 flower has 4 stamens with iila- 

 ments about as long as the ca- 

 lyx. The ripe pistillate catkins 

 are oblong, i to 2 cm. long, their 

 scales thickened and lobed at 

 the top; the round-obovate nut 

 is about 2.5 mm. long and narrowly winged 



Fig. 221. Thin-leaved Alder. 



5. RHOMBIC-LEAVED ALDER Alnus rhombifoUa Nuttall 



This tree is one of the largest North 

 American alders, attaining a height of 25 

 meters or more and a trunk diameter of 

 about I meter; it ranges from Washington 

 and Idaho, through Oregon to San Ber- 

 nardino county California, occurring most 

 abundantly in river valleys. 



The dark brown bark is thick, somewhat 

 fissured and scaly. The young twigs are 

 green and hairy, but early become reddish 

 and smooth, and finally brown. The buds 

 are narrow, hair}% bluntish, and about i 

 cm. long. The leaves are mostly oval, 

 sometimes broadly so, sometimes ovate, 

 blunt or pointed, thickish, irregularly finely 

 toothed, usually narrowed or wedge-shaped 

 at the base, 5 to 12 cm. long, the stalk i to 

 2 cm. long; they are hairy on both sides when young, and when mature are rather 



222 



Rhombic-leaved Alder. 



