Handbook of Teees of the Northern States and Canada. 443 



ovules sevei-al, suspended. Fruit a glabrous compressed linear margined tardily dehiscent 

 Jegume, containing few oblong compressed seeds with slender funicle and no albumen. 

 Name termed from Greek roots meaning brittle branclies. 

 For species see pp. 292-21)3. 



THE LOCUSTS. Genus ROBINIA L. 



Trees and shrubs with slender zigzag branchlets and minute superposed buds covered 

 by the enlarged bases of the petioles. They are confined to North America. Seven or eight 

 species are known, of which four are represented in the United States, three arborescent and 

 one shrubby. 



Leaves deciduous, unequally pinnate and with spinescent persistent stipules; leaflets 

 entire, petiolulate with minute bristle-like stipels. Floirers in racemes from the axils of 

 the leaves of the year with caducous bracts and bractlets ; calyx campanulate, .")-toothed. 

 the upper pair shorter and somewhat united ; corolla papilionaceous with large reflexed 

 obcordate standard, oblong curved free wings and obt\ise incurved keel-petals united below ; 

 stamens 10. the inferior united and one superior free at least to base ; anthers uniform or 

 every other one smaller; pistil superior, stipitate with subulate inflexed hairy style and ter- 

 minal stigma; ovules numerous, suspended from the ventral suture in two ranks. Fruit: pods, 

 compressed, linear-oblong, flat-margined along the seed-bearing suture, with 2 thin mem- 

 branous valves and containing several oblique reniform seeds with persistent incurved funicle, 

 fleshy cotyledons and reflexed radicle. 



The genus is named in honor of Jean and Vaspasean Robin, father and son, herbalists to 

 Henry IV, King of France, who first cultivated the Locust tree in Europe. 



KEY TO THE SPECIES. 



Flowers white ; branchlets and pods glabrous R. Pseudacacia. 



riowers pinkish ; branchlets and pods glandular-hispid R. viscosa. 



For spceics see pp. 2!IJf 297. 



RTJE FAMILY. RUTACE.E Juss. 



An important family of trees and shrubs with pungent or aromatic properties, widely 



distributed throughout warm and temperate regions, especially of the Old World, and most 



abundant in South Africa and Australia. About eight hundred eighty species, grouped in 



one hundred ten genera, are recognized, but only five of the genera are represented in the 



United States, this number including Citrus (the Bitter-sweet Orange, etc.) of Florida. 



Leaves compound (sometimes simple) usually glandular-punctate, without stipules or 

 with stipular spines. Floorers regular, perfect or unisexual, generally in cymes ; calyx with 

 3-5 lobes imbricated in the bud; petals ^-V>, hypogynous or perigynous. imbricated in the bud; 

 stamens as many as the petals or twice the number, distinct or united below and inserted on 

 the receptacle ; anthers iutrorse, longitudinally dehiscent : pistils 2-5, separate or united, 

 sessile or stipitate, the styles usually united and ovary containing 2 pedulous anatropous or 

 amphitropous ovules. Fruit usually a capsule but in other cases a samara or drupe; seed 

 with horny or crustaceous coat and containing an axile embryo in fleshy albumen. 



KEY TO THE GENERA, 



Fruit a 2-valved capsule ; leaves pinnate Xanthoxylum. 



Fruit a samara winged all around ; leaves trifoliate Ptelea. 



THE PRICKLY-ASHES. Genus XANTHOXYLUM L. 



Trees and shrubs of about one hundred species, with prickly twigs and of wide distribu- 

 tion in tropical and temperate regions. Five species are found in the United States of which 

 one is a shrub and the others small trees mainly of the southern states. The bark, especially 

 of the roots, of all the representatives of the genus contains active stimulant and tonic prop- 

 erties and is used in the treatment of rheumatism, to excite salivation and to relieve toothache. 



Leaves alternate, odd-pinnate, the leaflets generally opposite, oblique at base and entire 

 or crenulate. Flowers ^.maW. whitish or greenish, in axillary or terminal pedunculate cymes; 

 sepals 4-5 or ob.solete ; petals 4-5 ; stamens 4-5 and alternate with the petals ; pistils 2-5, 

 oblique, stipitate; ovaries distinct, 1-celled. 2-ovuled ; style short, slender and connivant. 

 Fruit a capsule with two thickish valves and containing 1-2 oblong seeds with smooth black 

 shining crustaceous testa, and often hanging from the open carpel at maturity suspended by a 

 slender funicle ; cotyledons foliaceous. 



The name is from two Greek words meaning yellow wood. 

 For speeics see pp. 298-299. 



