Unarmed trees, with large bipinnate leaves, widely spreading branches, and perfect or polygamous capitate pink or white flowers, the heads sometimes panicled. Calyx tubular to campanulate, 5-lobed. Corolla funnelform. Stamens numerous, longer than the corolla; filaments united near the base of the corolla. Pods linear, flat, 2-valved, the margins of the valves not separating from them. [In honor of Albizzi, an Italian naturalist.]

About 50 species, natives of warm and tropical regions of the Old World, the following typical.

2 Alb zzia Durazz Mag Tosc 34 II 1772 772

1. Albizzia Julibrissin Durazz. Pink Siris. Silk-Tree

Fig. 2430

A. julibrissin Durazz. Mag. Tosc. 34: 11. 1772.

A tree, up to 35° high, and trunk diameter of 1 1/2°, the bark thin and scaly, the slender twigs smooth, reddish-brown. Leaves 8'-16' long, with 8-16 pairs of pinnae; the rachis tipped by a spine; leaflets 25 to 35 pairs, oblong, inequilateral, acute, 5"-8" long, revolute-margined, dark green above, pale green and pubescent beneath; heads panicled, about 2' in diameter; flowers pink; stamens more than 1' long; ovary short-stalked; pod 4'-6' long, narrowed at both ends, papery; seeds oval, flat, 4"-5" long.

Virginia to Florida and Louisiana. Naturalized from southern Asia. April-July.

3. ÁCUAN Medic. Theod. Sp. 62. 1786.

[Desmanthus Willd. Sp. Pl. 4: 1044. 1806.] [Darlingtonia DC. Ann. Sci. Nat. 4: 97. 1825.]

Perennial herbs or shrubs, with bipinnate leaves, small stipules, and greenish or whitish small regular flowers in axillary peduncled heads or spikes. Flowers perfect, sessile, or the lowest sometimes staminate, neutral or apetalous. Calyx campanulate, its teeth short.

Petals valvate, distinct, or slightly united or coherent below: Stamens 10 or 5, distinct, mainly exserted; anthers all alike. Ovary nearly sessile; ovules 00. Pod linear, straight or curved, acute, glabrous, flat, several-seeded, 2-valved, the valves coriaceous or membranous.

About 10 species, natives of warm and tropical America, one of them widely distributed in tropical regions of the Old World. Type species: Mimosa virgata L.

Pods few, linear, erect, straight.

1.

A. leptoloba.

Pods numerous in globose heads, oblong, curved.

2.

A. illinoensis.

1 Albizzia Julibrissin Durazz Pink Siris Silk Tree 773

1. Acuan Leptóloba (T. & G.) Kuntze. Prairie Mimosa

Fig. 2431

Desmanthus leptolobus T. & G. Fl. N. A. 1: 402. 1840. Acuan leptoloba Kuntze, Rev. Gen. Pl. 158. 1891.

Herbaceous, ascending, branched, stems rough-angled, 2°-3° long. Leaves short-petioled, bipinnate; pinnae 5-10 pairs, sessile; leaflets 10-24 pairs, sessile, linear-lanceolate, acute, inequilateral, rounded at the base, usually glabrous, 1V-2" long, i" wide or less; peduncles 6"-12" long, few-flowered; stamens (always?) 5; pods 3-8, narrowly linear, acuminate, nearly straight, glabrous, about 3 times the length of the peduncle, 6-8-seeded.

Prairies, Kansas to Texas. Summer.

2. Acuan Illinoénsis (Michx.) Kuntze. Illinois Mimosa

Fig. 2432

Mimosa illinoensis Michx. Fl. Bor. Am. 2: 254.

1803. Acacia brachyloba Willd. Sp. Pl. 4: 1071. 1806. Desmanthus brachylobus Benth. in Hook. Journ.

Bot. 4: 358. 1842. A. illinoensis Kuntze, Rev. Gen. Pl. 158. 1891.

Ascending or erect, glabrous or nearly so, stems angled, 1°-3° high. Foliage resembling that of the preceding species, but the pinnae and obtusish leaflets are sometimes more numerous; peduncles 1'-2' long; pods numerous, densely capitate, oblong or lanceolate, strongly curved, 8"-12" long, acute, slightly impressed between the 2-5 seeds.

Prairies and river-banks, Ohio to Kentucky, Florida, South Dakota, Colorado, Texas and New Mexico. Illinois acacia. May-Sept.

2 Acuan Illino Nsis Michx Kuntze Illinois Mimosa 774