IIaM)BOOK of TkKKS ok IIIK XoiMUKKN SlATKS AND ("a.NADA. 443 



ovules several, siisiieiided. I'rnil a izlahiims coinpressed linear inn r;:inei| lardil.v deliiscent 

 legume, ((intainiuf,' tew oblunj.' ((uniiressed seeds with slender I'uuicle ;»nd no albumen. 

 Name formed from (Jreek roots meaning brittle branches. 

 For species see pp. 292-2V3. 



THE LOCUSTS. Genus ROBINIA L. 



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

 by the enl.irged bases (d" the petioles. They are confined to North America. Seven or eight 

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

 one shrubby. 



LcfliT.s' deciduous, uneiiually iiinnat(> and with spiiiescent persistent stipules; leaflets 

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

 the leaves of the year with caducous bracts and bractlets : calyx campanulate. fi-toftthed. 

 the upper i)air shorter and somewhat united: corolla papilionaceous with large reflexe(l 

 obcordate standard, oblong curved free wings and obtuse incurved keel-petals united below ; 

 stamens 10, the 9 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, susjx'uded from the vential suture in two ranks. Fruit: jjofls, 

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

 branous valves and containing several obliciue 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 lY, King of France, who first cultivated the Locust tree in Europe. 



KFA' TO THE SPECIES. 



Flowers white: branchlets and pods glabrous R. Pseudacacia. 



Flowers pinkish : branchlets and pods glandular-hispid R. viacosa. 



For species see pp. 2'.>.'i 297. 



RUE FAMILY. RUTACE.^ Juss. 



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



distributed throughout warm and temperate regions, especially of the Old AVorld, 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 



I'nited 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. Floireis regular, perfect or unisexvial. generally in cymes ; calyx with 

 3-ri lobes imbricated in the bud ; petals 3-r>, 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 introrse, longitudinally dehiscent; pistils 2-5, sei)arate or united, 

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

 aniiihilrnpous 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 GENEKA. 



Fruit a 2-valved capsule : leaves pinnate Xanthoxyluni. 



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 tro])ical and temi)erate 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 i)roi)- 

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



Leaves alternate. odd-i)innate. the leaflets generally opjiosite. oblique at base and entire 

 or crenulate. Floirers small, whitish or greenish, in axillary or terminal pedunculate cymes; 

 sepals 4-.") or obsolete: jjctals 4-."); stamens 4-."> and alternate with the petals: i)istils 2-.">. 

 oblique. stii)itate ; ovaries distinct. 1-celled. 2-ovuled ; style short, slender and couni\aur. 

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

 shining crustaceous testa, and often hanging from the open carpel at maturity susi)ended by a 

 slender funicle : cotyledons foliaceous. 



The name is from two Oreek words meaning yeUoir irood. 

 For species see pp. 2'JS-2ilO. 



