FAGACEAE. 97 



subtending 2 or 3 flowers, the calyx present. Pistillate aments seldom 

 drooping, the bracts membranous or thickened and woody, each bearing 2 

 or 3 pistils, the calyx wanting. Fruit a cone-like aggregate of the accres- 

 cent bracts each of which subtends a nut. 



Stamens 2 : bracts of the mature pistillate aments membranous, 3-lobed deciduous 

 with the nuts. 1. Betula. 



Stamens 4 (3-6) : bracts of the mature pistillate aments thickened and 



woody, persistent. 2. Alnus. 



1. BETULA [Tourn.] L. Shrubs or trees, the bark often aromatic. 

 Staminate flowers with 2 stamens, the anther-sacs separated. Bracts of the 

 pistillate aments 3-lobed, thin and appressed or ascending at maturity. — Spr. 

 — Birch. 



Fruiting aments peduncled : samaras wider than long. 1. B. nifjra. 



Bark brown : leaf-blades shining above : mature pistillate 

 bracts with 2 short broad divergent lateral lobes : nut 

 with triangular-obovate or cuneate wings. 2. if. lenta. 



Bark yellowish or silvery : leaf-blades dull above : mature 

 pistillate bracts with 2 ascending lateral lobes : nut 

 with orbicular-obovate wings. 3. B. alleghcnicnsis. 



1. B. nigra L. Tree becoming 30 m. tall, the younger bark silvery or yellow: 

 leaf -blades rhombic-ovate, 3-6 em. long^ broadly cuneate at the base, more or 

 less tomentose beneath except in age: staminate aments with suborbicular 

 bracts: mature pistillate aments 3-4 cm. long, less than 1 cm. thick, the bracts 

 6-7 mm. long, tomentulose: wings of the fruit reniform, ciliate. Common, 

 along streams. — Eiver-birch. Eed-birch. 



2. B. lenta L. Tree becoming 25 m. tall, the bark brown: leaf -blades ovate, 

 oblong-ovate, or oblong-lanceolate, 4-12 cm. long, rounded or cordate at the 

 base, silky on the nerves beneath: staminate aments with ovate bracts: mature 

 pistillate aments 1.5-3 cm. long, over 1 cm. thick, the bracts 5-6 mm. long and 

 quite or nearly as wide, usually glabrous: wings of the fruit triangular-obovate 

 or cuneate, not ciliate. — • Common, in woods and on hillsides. — Sweet-birch. 

 Cherry-birch. Black-birch. 



3. B. allegheniensis Britton. Tree becoming 30 m. tall, the bark yellowish or 

 silvery: leaf -blades ovate to oblong-ovate, 5-10 cm. long, rounded or cordate at 

 the base, pubescent on the nerves beneath: staminate aments with ovate or 

 oval-ovate bracts: mature pistillate aments 1.. 5-2.5 cm. long, very stout, the 

 bracts 7-9 mm. long, quite or fully as wide, ciliate : wings of the fruit orbicular- 

 obovate. — Susquehanna valley and tributary streams and in neighboring 

 ravines ; also in the Welsh mountains. — Schists, quartzite. — Southern Yel- 

 low-birch. 



2. ALNUS [Tourn.] L. Shrubs or trees, the bark astringent. Staminate 

 flowers with 3-6 stamens, the anther-sacs connected. Bracts of the pistillate 

 aments not lobed or obscurely so, woody and spreading at maturity. 



1. A. rugosa (Du Eoi) Spreng. Shrub, or tree becoming 13 m. tall: leaf- 

 blades thickish, obovate or oval, 4-10 cm. long: mature pistillate aments 1.5-2 

 cm. long, the bracts 3-lobed: nuts 1.5 mm. long, sharp-margined. — Common, in 

 low woods and thickets. — Winter and Spr. — Alder. Smooth-alder. 



Family 3. FAGACEAE. Beech Family. 



Shrubs or trees, the wood usually coarse-grained. Leaves sometimes 

 persistent : blades simple, entire, toothed, or lobed. Staminate aments 

 elongate or globular, the calyx of 4—7 partially united sepals. Pistillate 



Lancaster County Flora 7. 



