Trees of the Northern United States Part 15

ORDER =XIV. RHAMNaCEae.=

(BUCKTHORN FAMILY.)

An order mainly of shrubs, but including in the north-eastern United States two or three small trees.

GENUS =20. RHaMNUS.=

Shrubs or small trees with deciduous (rarely evergreen), usually alternate (rarely opposite), pinnately veined leaves. Flowers small, 4-parted, inconspicuous, in cl.u.s.ters in the axils of the leaves. Fruit berry-like, with 2 to 4 seed-like nuts.

* Branches terminating in thorns 1.

* Plant without thorns. (=A.=)

=A.= Leaves deciduous 2.

=A.= Leaves evergreen 3.

[Ill.u.s.tration: R. cathartica.]

1. =Rhamnus cathartica, L.= (COMMON BUCKTHORN.) Leaves ovate, minutely serrate, alternate or many of them opposite; branchlets terminating in thorns. Flowers greenish. Fruit globular, 1/3 in. in diameter, black with a green juice, and 3 or 4 seeds; ripe in September. A shrub or small tree, 10 to 15 ft. high, from Europe; cultivated for hedges, and found wild in a few places, where it forms a small tree.

[Ill.u.s.tration: R. Caroliniana.]

2. Rhamnus Caroliniana, Walt. (CAROLINA BUCKTHORN.) Leaves 3 to 5 in.

long, alternate, oblong, wavy and obscurely serrulate, nearly smooth, on slender p.u.b.escent petioles. Flowers greenish, 5-parted, solitary or in umbellate cl.u.s.ters in the axils. Fruit berry-like, globular, the size of peas, 3-seeded, black when ripe in September. A thornless shrub or small tree, 5 to 20 ft. high. New Jersey, south and west. Usually a shrub except in the Southern States.

[Ill.u.s.tration: R. Califrnicus.]

3. =Rhamnus Califrnicus=, Esch. (CALIFORNIA BUCKTHORN.) Leaves evergreen, oval-oblong to elliptical, 1 to 4 in. long, rather obtuse, sometimes acute, generally rounded at base, serrulate or entire. Fruit blackish purple, with thin pulp, in., 2- to 3-seeded. A spreading shrub, 5 to 18 ft. high, without thorns; from California.

GENUS =21. HOVeNIA.=

Leaves alternate, deciduous, simple, oblique at base. Fruit an obscurely 3-lobed, 3-celled, 3-seeded pod in dichotomous cl.u.s.ters, both axillary and terminal.

[Ill.u.s.tration: H. dulcis]

=Hovenia dulcis=, Thunb. Leaves long-petioled, more or less ovate to cordate, serrate, palmately 3-ribbed, much darker on the upper surface; both sides slightly roughened with scattered hairs. Fruit sweet, edible, in cl.u.s.ters in the axils of the leaves; seeds lens-shaped, with a ridge on the inner side. Flowers white; in July. A large, broad-topped tree, introduced from j.a.pan. Hardy at Washington, but dies to the ground in the Arnold Arboretum, Ma.s.sachusetts.

GENUS =22. ZZYPHUS.=

Leaves simple, alternate, deciduous, 3-ribbed. Flowers axillary, 5-petaled. Fruit fleshy, drupe-like, containing a 1- to 2-celled nut.

[Ill.u.s.tration: Z. vulgaris.]

=Zzyphus vulgaris=, Lam. (JUJUBE.) Leaves ovate-lanceolate, obtuse, serrate, smooth, and glossy green on both sides, upper side quite dark; slightly hairy beneath on the veins; p.r.i.c.kles twin, one recurved, sometimes none. New growth of the year green, and resembling a once-pinnate compound leaf and usually dropping off in the autumn like one. Leaves 10 to 20 on a twig, 2-ranked; flowers and drupes nearly sessile in the axils; fruit small ( in.), blood-red when ripe. A small tree (10 to 30 ft. high), of recent introduction from Syria; hardy at Philadelphia, but needing some protection at the Arnold Arboretum, Ma.s.sachusetts.

ORDER =XV. SAPINDaCEae.= (SOAPBERRY FAMILY.)

A large order represented in all countries, and so varied in its characteristics as to form several sub-orders.

GENUS =23. aeSCULUS.=

Deciduous trees or sometimes shrubs, with opposite, palmately compound leaves with serrated, straight-veined leaflets. Flowers usually conspicuous in dense terminal panicles. Fruit large, leathery-coated, often rough, with one or few large Chestnut-like but bitter seeds. Fruit large in midsummer, hanging on the tree until frost.

* Fruit p.r.i.c.kly. (=A.=)

=A.= Leaflets usually 7; flowers widely spreading 1.

=A.= Leaflets 5-7, red-spotted and rough; flowers rosy red _aesculus rubicunda_ (1).

=A.= Leaflets usually 5; flowers not much spreading 2.

* Fruit smooth or nearly so. (=B.=)

=B.= Flowers bright red 3.

=B.= Flowers yellow, purplish or pinkish 4.

=B.= Flowers white, in long, slender, erect cl.u.s.ters 5.

[Ill.u.s.tration: ae. Hippocastanum.]

1. =aesculus Hippocastanum.= (COMMON HORSE-CHESTNUT.) Leaves of 7 obovate, abruptly pointed, serrated leaflets. Flowers very showy in large cl.u.s.ters, with 5 white, purple and yellow spotted, broadly spreading petals. A variety with double flowers is in cultivation. May or June. Fruit large, covered with p.r.i.c.kles. Seeds large, chestnut-colored. Tree of large size, with brown twigs; cultivated everywhere; from Asia.

[Ill.u.s.tration: ae. rubicunda.]

_aesculus rubicunda_ (Red-flowering Horse-chestnut) is frequent in cultivation; leaflets 5 to 7, red-spotted and rough; flowers rosy red.

It is probably a hybrid between the common Horse-chestnut and one of the Buckeyes.

[Ill.u.s.tration: ae glabra.]

2. =aesculus glabra=, Willd. (OHIO BUCKEYE.) Leaves with 5 oval-oblong, ac.u.minate, serrate, smooth leaflets. Flowers not showy, yellowish-white, with 4 somewhat irregular, slightly spreading petals. June. Fruit small, 1 in. in diameter, covered with p.r.i.c.kles, at least when young; ripe in autumn. Small to large tree, wild in the basin of the Ohio River, along river-banks. Sometimes cultivated.

[Ill.u.s.tration: ae. Pavia.]

3. =aesculus Pavia=, L. (RED BUCKEYE.) Leaves of 5 to 7 oblong-lanceolate, finely serrate, generally smooth leaflets, of a shining green color, with purple veins and petioles. Flowers (corolla and calyx) bright red, with included stamens; corolla of 4 petals, not spreading; calyx tubular. Fruit smooth, oblong-obovate, 1 in. long.

Small tree or shrub, 10 to 20 ft. high, with purple twigs. Virginia west and south, and occasionally cultivated throughout.

[Ill.u.s.tration: ae. flava.]

4. =aesculus flava=, Ait. (SWEET BUCKEYE.) Leaves with 5 to 7 serrulate, elliptical, ac.u.minate leaflets, usually smooth, sometimes minutely p.u.b.escent beneath; the p.u.b.escent petiole flattish toward the base.

Flowers yellow, not spreading. Spring. Fruit globose, uneven but not p.r.i.c.kly, 2 in. in diameter. Seeds large (1 in.), 1 or 2 in number, mahogany-colored; ripe in autumn. Often a large tree, sometimes only a shrub, 6 to 70 ft. high, in rich woods; Virginia to Indiana, and southward. Cultivated occasionally throughout.