52. VlTACEAE 109 



1. Rhamnus L. — Buckthorn 

 1. Winter buds scaly. 



2. Leaves opposite or subopposite, ovate, abruptly acute; twigs 

 rigid, often spine-like; flowers usually 4-merous; petals 

 piesent; drupe with 3 or 4 nutlets; roadsides and edges of 

 woods, occasional, in the northern half of 111.; nal. from 



Eurasia. May-June. Conunon Buckthorn R. cathartica L. 



2. Leaves alternate; native shrubs 1-2 m tall; twigs not at all 



spine-like. 



3. Leaves elliptical, serrulate, pubescent beneath; twigs puberu- 



lent; flowers 4-inerous; petals present, small; drupe with 2 



nutlets; alluvial soil, bluffs, river banks, the common species 



in 111.; absent from the southern counties. May 



R. lanceolata Pursh 



3. Leaves oval or obovate, strongly veined, crenate-serrate; twigs 

 glabrous; flowers 5-merous; petals none; drupe with 3 

 nutlets; wooded swamps, chiefly in n. 111. Alder Buckthorn 



R. alnifolia L'Her. 



1. Winter buds naked; leaves alternate; flowers 5-merous; shrubs or 



small trees 3-10 m tall. 



4. Leaves obscurely serrulate; flowers in peduncled cymes, the 



pedicels pubescent; calyx-lobes lanceolate, aciuninate; drvipe 



8-10 mm in diameter, with 3 nutlets; wooded slopes, rare; 



known from Gallatin, Jackson, Monroe, Pope, and Randolph 



coimties. May-June. Carolina Buckthorn 



R. caroliniana Walt. 



4. Leaves entire or undulate; flowers fascicled; pedicels glabrous; 

 calyx-lobes ovate, acute; drupe 6-8 mm in diameter, with 2 

 nutlets; woods and roadsides, occasional; nat. from Eurasia. 

 May- June. Glossy Buckthorn R. frangula L. 



2. Ceanothus L. 

 1. Leaves ovate, acute; seeds smooth; thickets and open woods, 



common. June- July. New Jersey Tea C. americanus L. 



1. Leaves elliptic-lanceolate; seeds pitted; sandy soil in the northern 



counties of 111., not common. \C. ovalis Bigel.] C. ovatus Desf. 



52. Vitaceae Lindl. — Grape Family 

 1. Leaves simple, or pinnately compound. 



2. Inflorescence longer than broad; petals united in a cap, falling away 

 without separating; pith interrupted at the nodes; fruit edible; leaves 



simple, palmately-lobed or dentate 1. Vitis 



2. Inflorescence broader than long; petals separate, spreading; pith not 



interrupted at the nodes; fruit not edible 2. Ampelopsis 



1. Leaves palmately compound with usually 5 leaflets 3. Parthenocissus 



1. Vitis L. — Grape 

 1. Mature leaves grayish or rusty arachnoid-pubescent beneath. 

 2. Pubescence of lower leaf surface a thin web; grapes 1-2.5 cm in 



