BETULACEAE (BIRCH FAMILY) 333 



clustered, spiked, or in scaly catkins; the l-celled and l-seeded nut with or 

 without a foliaceous involucre. Ovary 2-celled, with 2 pendulous anatropous 

 ovules in each cell ; fruit seemingly l-celled and 1-ovuled ; styles 2. Seed with 

 no albumen, filled with the embryo, and with 1 integument. 



Tribe I. CORYLEAE. Sterile catkins pendulous, with no calyx ; stamens 3 or more to each bract 

 and more or less adnate to it, the filaments often forked (anthers l-celled). Fertile flowers in a 

 short ament or head, 2 to each bract, and each with one or more bractlets which form a folia- 

 aceous involucre to the nut. 

 * Bract of staminate flower furnished with a pair of bractlets inside ; fertile flowers few. 



1. Corylus. Involucre leafy-coriaceous, inclosing the large acorn-like nut. 



* * Bract of staminate flower simple ; fertile flowers in short catkins; nut small, achene-like. 



2. Ostrya. Each ovary and nut included in a bladdery and closed bag. 



3. Carpinus. Each nut subtended by an enlarged spreading leafy bractlet. 



Tribe II. BETULEAE. Flowers in scaly catkins, 2 or 3 to each bract. Sterile catkins pendulous. 

 Stamens 2-4, and calyx usually 2^-parted. Fertile flowers with no calyx, and no involucre 

 to the small compressed and often winged nut. 



4. Betula. Stamens 2, bifid. Fertile scales thin, 3-lobed, deciduous with or soon after the nuts. 



5. Alnus. Stamens 4. Fertile scales thick, becoming woody, long-persistent. 



1. C6RYLUS [Tourn.] L. HAZELNUT. FILBERT 



Sterile flowers consisting of 8 (half-) stamens with l-celled anthers, their 

 short filaments and pair of scaly bractlets cohering more or less with the inner 

 face of the scale of the catkin. Fertile flowers several from a scaly bud ; ovary 

 tipped with the short limb of the adherent calyx, one of the ovules sterile ; style 

 short ; stigmas 2, red, elongated and slender. Nut ovoid or subglobose, inclosed 

 in a leafy or partly coriaceous cup or involucre consisting of the two bractlets 

 enlarged and often grown together and lacerated at the border. Cotyledons very 

 thick (raised to the surface in germination), sweet and edible ; the short radicle 

 included. Shrubs or small trees, with thinnish doubly-toothed leaves (folded 

 lengthwise in the bud), flowering in early spring ; sterile catkins single or fas- 

 cicled from scaly buds of the axils of the preceding year, the fertile terminating 

 early leafy shoots. (The classical name, probably from icbpvs, a helmet, from 

 the involucre.) 



1. C. americana Walt. (HAZELNUT.) Twigs and petioles often glandular- 

 bristly ; leaves roundish-heart-shaped, pointed; involucre open above down to 

 the globose nut, of 2 broad foliaceous cut-toothed almost ^distinct bracts, their 

 bases coriaceous and downy or with glandular bristles intermixed ; pericarp 

 bony. Thickets, N. E. to Sask., and southw. 



2. C. rostrata Ait. (BEAKED H.) Twigs and petioles not glandular-bristly ; 

 leaves ovate or ovate-oblong, somewhat heart-shaped, pointed ; involucre of 

 united bracts, much prolonged above the ovoid nut into a narrow tubular beak, 

 densely bristly ; pericarp thinnish and membranaceous. Que. to B. C., s. to 

 Del., Mich., Mo., and westw.; also in the mts. to Ga. 



2. 6STRYA [Mich.] Scop. HOP HORNBEAM. IRONWOOD. 



Sterile flowers consisting of several stamens in the axil of each bract ; fila- 

 ments short, often forked, bearing l-celled (half-) anthers ; their tips hairy. 

 Fertile flowers a pair to each deciduous bract, each of an incompletely 2-celled 

 2-ovuled ovary, crowned with the short bearded border of the adherent calyx, 

 tipped with 2 long-linear stigmas, and inclosed in a tubular bractlet, which in 

 fruit becomes a closed bladdery ellipsoid bag, very much larger than the small 

 smooth nut ; these inflated involucres loosely imbricated to form a sort of stro- 

 bile, in appearance like that of the Hop. Slender trees, with very hard wood, 

 brownish furrowed bark, and foliage resembling that of Birch ; leaves open and 

 concave in the bud, more or less plaited on the straight veins. Flowers appear- 

 ing with the leaves ; the sterile catkins 1-3 together from- scaly buds at the tips 



