394 OAK FAMILY. 



1. BETULA, BIRCH. (The ancient Latin name.) Trees with slender 

 spray (or a few low shrubs), more or less spicy-aromatic twigs, sessile 

 scaly buds, flowers in early spring along with the leaves ; the sterile 

 catkins golden yellow ; the fertile ones mostly terminating very short 

 2-leaved branches of the season. 



» Trunk toith brown or yellow-gray bark, the inner bark, twigs and thin 

 strnif/lit-veined leaves spicy-aromatic; petioles short; thick fruiting 

 catkins with their thin scales rather persistent ; fruit with narrow wing. 



B. l^nta, Linn. Sweet, Black, or Cherry Birch. A rather large tree, 

 500-75"^, with fine-grained valuable wood, dark brown close bark on the 

 trunk (not peeling in thin layers) and bronze-reddish twigs, very aromatic ; 

 leaves oblong-ovate and somewhat heart-shaped, sharply doubly serrate all 

 round, soon glossy above and almost smooth ; fruiting catkins oblong- 

 cylindrical, the scales with divergent lobes. Rich woods, N. Eng., W. and S. 



B. Ititea, Michx. f. Yellow or Gray Birch. Less aromatic ; bark 

 of trunk yellowish-gray and somewhat silvery, separating in thin layers ; 

 leaves duller, more downy, and rarely at all heart-shaped ; fruiting cat- 

 kins short-oblong, with thinner and narrower barely spreading-lobed 

 scales. Same general range. 



* * Trunk with chalky-white bark peeling horizontally in thin sheets ; 

 leaves and narrow cylindrical smooth catkins slender-stalked ; bracts 

 falling with the broad-winged fruit. 



B. diba, Linn. European White Birch, but much cultivated, partic- 

 ularly the weeping and cut-leaved forms ; tree 50°-60°, with open top, and 

 small (in the normal form) leaves which are triangular-ovate with a truncate 

 or rounded (or even somewhat cordate) base, and not strongly acuminate. 



B. populif61ia, Ait. American White Birch, Gray Birch. Small 

 slender tree, 15°-30°, with mostly larger dangling leaves than the last, 

 very lustrous above, strongly triangular-ovate or diamond-ovate, the base 

 slanting, and the apex very long-acuminate. Poor soils, N. Eng. to Del., 

 and L. Ontario. 



B. papyrifera. Marsh. Paper or Canoe Birch. Large tree, from upper 

 part of Penn. N., mostly far N. and N. W. ; with ovate and even heart- 

 shaped leaves (dull and often pubescent beneath, and dark green above), 

 and more papery bark than in White Birch, separating in ample sheets. 



* * * Trunk with greenish-brown bark, hardly peeling in layers, reddish 

 twigs little aromatic, and oblong downy short-stalked catkins ; icings of 

 fruit broad. 



B. nigra, Linn. River or Red Birch. Middle-sized tree of low river 

 banks, commonest S. (but growing from Mass. to Minn, and S.); leaves 

 rhombic-ovate, whitish and mostly downy beneath. 



* * * * Shrubs with broion tight bark, small thirkish crenate leaves, and 



oblong or cylindrical glabrous mostly erect short-pedunrled catkins. 

 B. piimila, Linn. Low or Dwarf Birch. Erect or ascending, 2°-8° ; 

 leaves ohovate or orbicular, soft-downy beneath. Bogs, Conn., S. and W. 



2. ALNUS, ALDER. (Ancient Latin name. ) Small trees or shrubs, 

 with narrow leaf-buds of very few scales and often stalked, and catkins 

 mostly clustered or racemed on leafless branchlets or peduncles. 



* Flowers with the leaves in spring, the sterile from catkins which were 

 naked over winter, lohile the fertile catkin was inclosed in a scaly bud. 



A. viridis, DC. Green or Mountain Aluer. Oh mountains and far 

 N. ; ',i'^-ii° high ; leaves round-oval or ovate, glutinous ; fruit with a broad 

 thin wing. 



