Tribe I. BETULEae. Flowers in scaly catkins, 2 or 3 to each bract.

Sterile catkins pendulous. Stamens 2--4, and calyx usually 2--4-parted.

Fertile flowers with no calyx, and no involucre to the compressed and often winged small nut. Ovary 2-celled, 2-ovuled.

1. Betula. Stamens 2, bifid. Fertile scales thin, 3-lobed, deciduous with the nuts.

2. Alnus. Stamens 4. Fertile scales thick, entire, persisting after the nuts have fallen.

Tribe II. 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 1-celled). Fertile flowers in a short ament or head, 2 to each bract, and each with one or more bractlets which form a foliaceous involucre to the nut. Ovary 2-celled, 2-ovuled.

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

3. Corylus. Involucre leafy-coriaceous, enclosing the large bony nut.

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

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

5. Carpinus. Each nut subtended by an enlarged leafy bractlet.

Tribe III. QUERCINEae. Sterile flowers with 4--7-lobed calyx and stamens indefinite (3--20). Fertile flowers 1 or few, enclosed in a cupule consisting of consolidated bracts, which becomes indurated (scaly or p.r.i.c.kly) and surrounds or encloses the nut.

[*] Sterile flowers in slender catkins.

6. Quercus. Cupule 1-flowered, scaly and entire; nut hard and terete.

7. Castanea. Cupule 2--4-flowered, forming a p.r.i.c.kly hard bur, 2--4-valved when ripe.

[*][*] Sterile flowers in a small head.

8. f.a.gus. Cupule 2-flowered, 4-valved, containing 2 sharply triangular nuts.

1. BeTULA, Tourn. BIRCH.

Sterile flowers 3, and bractlets 2, to each shield-shaped scale or bract of the catkins, consisting each of a calyx of one scale bearing 4 short filaments with 1-celled anthers (or strictly of two 2-parted filaments, each division bearing an anther-cell). Fertile flowers 2 or 3 to each 3-lobed bract, without bractlets or calyx, each of a naked ovary, becoming a broadly winged and scale-like nutlet (or small samara) crowned with the two spreading stigmas.--Outer bark usually separable in sheets, that of the branchlets dotted. Twigs and leaves often spicy-aromatic. Foliage mostly thin and light. Buds sessile, scaly.

Sterile catkins long and drooping, terminal and lateral, sessile, formed in summer, remaining naked through the succeeding winter, and expanding their golden flowers in early spring, with or preceding the leaves; fertile catkins oblong or cylindrical, peduncled, usually terminating very short 2-leaved early lateral branches of the season. (The ancient Latin name, of Celtic origin.)

[*] _Trees, with brown or yellow-gray bark, sweet-aromatic as well as the twigs, membranaceous and straight-veined Hornbeam-like leaves heart-shaped or rounded at base, on short petioles, and sessile very thick fruiting catkins; their scales about equally 3-cleft, rather persistent; wing of fruit not broader than the seed-bearing body._

1. B. lenta, L. (CHERRY B. SWEET or BLACK BIRCH.) _Bark_ of trunk _dark brown, close_ (outer layers scarcely laminate), very sweet-aromatic; leaves ovate or oblong-ovate from a more or less heart-shaped base, ac.u.minate, sharply and finely doubly serrate all round, when mature shining or bright green above and glabrous except on the veins beneath; _fruiting catkins oblong-cylindrical_ (1--1' long), the scales with short and _divergent lobes_.--Rich woodlands, Newf. to N. Del., and south in the mountains, west to Minn., and S. Ind. Tree 50--75 high, with reddish bronze-colored spray; wood rose-colored, fine-grained, valuable for cabinet-work.

2. B. lutea, Michx. f. (YELLOW or GRAY BIRCH.) _Bark_ of trunk _yellowish- or silvery-gray, detaching in very thin filmy layers_, within and the twigs much less aromatic; leaves (3--5' long) slightly or not at all heart-shaped and often narrowish toward the base, duller-green above and usually more downy on the veins beneath; fruiting catkins _oblong-ovoid_ (1' or less in length, 6--9" thick), the thinner scales (5--6" long) twice as large as in n. 1, and with narrower _barely spreading lobes_.--Rich moist woodlands, Canada and N. Eng. to Del., west to Minn.; also along high peaks to Tenn. and N. C. Often 60--90 high at the north; wood whiter and less valuable.

[*][*] _Trees, with chalky-white bark separable in thin sheets, ovate or triangular leaves of firmer texture, on long slender petioles; fruiting catkins cylindrical, usually hanging on rather slender peduncles; their scales glabrous, with short diverging lobes, freely deciduous; wing of the fruit much broader than its body._

3. B. populiflia, Ait. (AMERICAN WHITE BIRCH. GRAY BIRCH.) Trunk usually ascending (15--30 high); _leaves triangular_ (deltoid), _very taper-pointed_ (usually abruptly), truncate or nearly so at the broad base, _smooth and shining both sides_, except the resinous glands when young. (B. alba, var. populifolia, _s.p.a.ch_.)--Poor sandy soils, N.

Brunswick to Del., west to L. Ontario. Bark much less separable than the next; leaves on slender petioles, tremulous as those of the aspen.

4. B. papyrifera, Marshall. (PAPER or CANOE BIRCH. WHITE BIRCH.) _Leaves ovate, taper-pointed_, heart-shaped or abrupt (or rarely wedge-shaped) at base, _smooth and green above_, pale, glandular-dotted, and a little hairy on the veins beneath, sharply and unequally doubly serrate, 3--4 times the length of the petiole. (B. papyracea, _Ait._)--Rich woodlands and stream-banks, N. Eng. to N. Penn., N. Ill., and Minn., and far north and westward. Tree 50--75 high, with bark freely splitting into paper-like layers.--Var. MINOR, Tuckerman, is a dwarf form of the alpine region of the White Mts.

[*][*][*] _Tree, with greenish-brown bark, somewhat laminate, and reddish twigs, ovate leaves whitish beneath, and soft-downy peduncled fruiting catkins._

5. B. ngra, L. (RIVER or RED BIRCH.) Leaves rhombic-ovate, acutish at both ends, irregularly doubly serrate, whitish and (until old) downy underneath; petioles and peduncle of nearly the same length (3--7") and with the oblong catkin tomentose; the bracts with oblong linear nearly equal lobes; fruit broadly winged.--Banks of streams, Ma.s.s, to Fla., west to Minn., E. Kan., and Tex. Tree 50--75 high, with light-colored wood and somewhat Alder-like leaves.

[*][*][*][*] _Shrubs, with brownish bark, rounded or wedge-shaped crenate and mostly small leaves of thickish or coriaceous texture, and oblong or cylindrical glabrous and mostly erect catkins, on short peduncles._

6. B. pumila, L. (LOW BIRCH.) Stems (2--8 high) erect or ascending, _not glandular_; young branches and lower face of young leaves mostly _soft-downy; leaves_ obovate, roundish, or orbicular (6--16" long), _pale beneath, veinlets on both faces finely reticulated_; wing of the fruit mostly narrower than the body.--Bogs, W. Conn, and N. J. to Ind.

and Minn., and northward throughout Canada. Leaves usually not at all resiniferous or glandular-dotted.

7. B. glandulsa, Michx. (DWARF BIRCH.) Stems erect or mostly spreading (1--4 high), or when alpine proc.u.mbent; _branchlets glabrous, conspicuously dotted with resinous wart-like glands_; leaves roundish wedge-obovate or sometimes...o...b..cular (6--9" long), green and glabrous both sides, less reticulated; fruiting catkins mostly shorter and oblong or oval; wing of the fruit narrower than or sometimes equalling the body.--High mountains of N. Eng. and N. Y., to L. Superior, and far northward.

2. aLNUS, Tourn. ALDER.

Sterile catkins elongated and drooping, with 4 or 5 bractlets and 3 (rarely 6) flowers upon each short-stalked shield-shaped scale; each flower usually with a 3--5-parted calyx and as many stamens; filaments short and simple; anthers 2-celled. Fertile catkins ovoid or oblong; the fleshy scales each 2--3-flowered, with a calyx of 4 little scales adherent to the scales or bracts of the catkin, which are thick and woody in fruit, wedge-obovate, truncate, or 3--5-lobed, and persistent.--Shrubs or small trees, with few-scaled leaf-buds, and solitary or often racemose-cl.u.s.tered catkins, terminating leafless branchlets or peduncles. (The ancient Latin name.)

-- 1. _Flowers developed in spring with the leaves; the sterile from catkins which have remained naked over winter; while the fertile have been enclosed in a scaly bud; fruit with a conspicuous thin wing, as in_ Birch.

1. A. viridis, DC. (GREEN or MOUNTAIN ALDER.) Shrub 3--8 high; leaves round-oval, ovate, or slightly heart-shaped, glutinous and smooth or softly downy beneath, irregularly serrulate or biserrulate with very sharp and closely set teeth, sometimes sinuate-toothed and serrulate (var. SINUaTA, Regel), on young shoots often cut-toothed; fertile catkins slender-stalked, cl.u.s.tered, ovoid (6--8" long).--On mountains and mountain streams, Newf. to W. Ma.s.s., N. Y., L. Superior, and far north and west; also in the Alleghanies to N. C. (Eu., Asia.)

-- 2. _Flowers developed in earliest spring, before the leaves, from mostly cl.u.s.tered catkins which (of both sorts) were formed the foregoing summer and have remained naked over winter; fruit wingless or with a narrow coriaceous margin._

2. A. incana, Willd. (SPECKLED or h.o.a.rY A.) _Leaves broadly oval or ovate, rounded at base_, sharply and often doubly serrate, _whitened and mostly downy beneath_; stipules oblong-lanceolate; fruit orbicular.--Borders of streams and swamps, Newf. to Ma.s.s., E. Neb., Minn., and westward. Shrub or tree 8--20 high; the common Alder northward. (Eu., Asia.)

3. A. serrulata, Willd. (SMOOTH A.) _Leaves obovate, acute at base_, sharply serrate with minute teeth, thickish, _green both sides_, smooth or often downy beneath; stipules oval; fruit ovate.--Borders of streams and swamps, Ma.s.s. to Fla., west to S. E. Minn. and Tex.; common. Shrub forming dense thickets, or sometimes at the south a small tree 6--35 high.

-- 3. _Flowers in autumn (Sept.) from catkins of the season; the fertile mostly solitary in the axils of the leaves, ripening the fruit a year later; fruit wingless._

4. A. maritima, Muhl. (SEA-SIDE A.) Glabrous; leaves oblong, ovate, or obovate with a wedge-shaped base, slender-petioled, sharply serrulate, bright green, or rather rusty beneath; fruiting catkins large, ovoid or oblong (9--12" long, 6" thick).--Borders of streams and swamps. S.

Del. and E. Md., near the coast. Small tree 15--25 high. (E. Asia.)

3. CoRYLUS, Tourn. HAZEL-NUT. FILBERT.

Sterile flowers in drooping cylindrical catkins, consisting of 8 (half-) stamens with 1-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 in a scaly bud, each a single ovary in the axil of a scale or bract, and accompanied by a pair of lateral bractlets; ovary tipped with a short limb of the adherent calyx, incompletely 2-celled, with 2 pendulous ovules, one of them sterile; style short; stigmas 2, elongated and slender. Nut ovoid or oblong, bony, enclosed in a leafy or partly coriaceous cup or involucre, consisting of the two bractlets enlarged and often grown together, lacerated at the border. Cotyledons very thick (raised to the surface in germination), 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 fascicled from scaly buds of the axils of the preceding year, the fertile terminating early leafy shoots. (The cla.s.sical name, probably from ?????, _a helmet_, from the involucre.)

1. C. Americana, Walt. (WILD HAZEL-NUT.) _Leaves roundish-heart-shaped_, pointed; _involucre open above_ down to the globose nut, _of 2 broad foliaceous cut-toothed almost distinct bracts_, their base coriaceous and downy, or with glandular bristles intermixed.--Thickets, N.

Eng. to Ont. and Dak., and southward. Twigs and petioles often glandular-bristly.

2. C. rostrata, Ait. (BEAKED HAZEL-NUT.) _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_.--N. Scotia to northern N. J., Mich., Minn., and westward, and south in the mountains to Ga. Shrub 2--6 high.

4. oSTRYA, Micheli. HOP-HORNBEAM. IRON-WOOD.

Sterile flowers in drooping cylindrical catkins, consisting of several stamens in the axil of each bract; filaments short, often forked, bearing 1-celled (half-) anthers; their tips hairy. Fertile flowers in short catkins; 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 enclosed in a tubular bractlet, which in fruit becomes a closed bladdery oblong bag, very much larger than the small and smooth nut; these inflated involucres loosely imbricated to form a sort of strobile, 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 in the spring, appearing with the leaves; the sterile catkins 1--3 together from scaly buds at the tip of the branches of the preceding year; the fertile single, terminating short leafy shoots of the season.

(The cla.s.sical name.)

1. O. Virginica, Willd. (AMERICAN HOP-HORNBEAM. LEVER-WOOD.) Leaves oblong-ovate, taper-pointed, very sharply doubly serrate, downy beneath, with 11--15 princ.i.p.al veins; buds acute; involucral sacs bristly-hairy at the base.--Rich woods, common, from the Atlantic to N. Minn., Neb., E. Kan., and southward. Tree 25--45 high; hop-like strobiles full-grown in Aug.