794 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



A few of the species are troublesome weeds and the leaves and unripe 

 fruits of several of them are reported to be poisonous, e. g., those of the 

 black nightshade (S. nigrum), S. triflorum, S. elaeagnifolium, and 

 S. rostratum. An alkaloid, solanin, is the active principle. However, 

 the fruits of the cultivated "wonderberry," a form of S. nigrum, are 

 used for making preserves and desserts. 



Key to the species 



1. Fruit closely invested by the accrescent calyx, this densely armed with long, 



straight, very sharp, straw-colored spines; stems and leaves similarly 



armed; plants annual; leaves pinnatifid or bipinnatifid (2). 



2. Herbage and corolla not glandular, copiously stellate-pubescent, often also 



puberulent; leaf segments broad, very obtuse; corolla yellow, 15 to 



25 mm. in diameter 1. S. rostratum. 



2. Herbage and corolla glandular-puberulent, frequently also villous or hirsute 

 with simple or forked, nonglandular hairs (3) . 

 3. Corolla violet; leaf segments broadly ovate or obovate, very obtuse. 



2. S. HETERODOXUM. 



3. Corolla yellow; leaf segments linear or lanceolate, acute or acutish; spines, 



when fresh, nearly black at base 3. S. lumholtzianum. 



1. Fruit not invested by the calyx, or loosely so (4). 



4. Herbage and calyx spiny, or if (exceptionally) unarmed, then densely and 



minutely whitish lepidote; corolla 20 to 30 mm. in diameter, purple, 



violet, or nearly white (5) . 



5. Leaf blades pinnatifid or bipinnatifid; spines up to 20 mm. long, often 



stout; stems and leaves copiously villous, the pubescence more or less 



glandular; plant annual; calyx loosely investing the fruit. 



4. S. SISYMBRIIFOLITJM. 



5. Leaf blades oblong or lanceolate, entire to coarsely sinuate-dentate; spines 



not more than 5 mm. long, slender, sometimes wanting; stems and 

 leaves densely and minutely whitish lepidote; plant perennial, with 

 long, deep, creeping rootstocks; calyx not investing the fruit or very 



loosely investing it at base 5. S. elaeagnifolium. 



4. Herbage and calyx not spiny; pubescence never lepidote (6). 



6. Plants with nearly globose tubers and long slender stolons; leaves pinnate, 



with 5 or more leaflets, some of these often very small; herbage pilose, 



usually sparsely so, with flat, simple, flaccid hairs; corolla 12 to 18 mm. 



in diameter (7). 



7. Leaflets oval, ovate, or obovate; corolla angulately 5-toothed, normally 



violet 6. S. FENDLERI. 



7. Leaflets narrowly lanceolate to broadly oblong-lanceolate; corolla 



deeply 5-cleft, normally white; plant often very sparsely pubescent, 



or glabrate 7. S. jamesii. 



6. Plants not tuberiferous or stoloniferous (8). 



8. Corolla violet or lilac purple, rarely white, 20 to 30 mm. in diameter, 



angulately 5-lobed; peduncle shorter than the pedicels, the latter with 

 a cupulate thickening at base; plant perennial, becoming some- 

 what woody at base, puberulent or soft-pilose, sometimes copiously 

 glandular but usually without glandular hairs; leaf blades ovate to 

 oblong-lanceolate, entire or undulate, occasionally somewhat 



auriculate at base 8. S. xanti. 



8. Corolla white or whitish (sometimes tinged with purple), not more 

 than 20 mm. in diameter, deeply 5-cleft; pedicels not cupulate at 

 base or very obscurely so (9). 

 9. Flowers solitary or geminate (exceptionally in 3's or 4's) , on slender, 

 strongly deflexed pedicels, without an evident peduncle; stems, 

 leaves, and calyx pubescent with stiff more or less spreading hairs; 

 seeds radially rugose; plant annual; leaf blades ovate to oblong- 

 lanceolate, entire or slightly repand 9. S. DEFLEXUM. 



9. Flowers commonly in cymes (sometimes solitary), these borne on 

 peduncles nearly as long as to longer than the pedicels; pubes- 

 cence of more or less appressed, or of soft and viscid hairs; seeds 

 not radially rugose (10). 



