256 



RUBIACEAE. 



VOL. III. 



5. SPERMACOCE L. Sp. PI. 102. 1753. 



Herbs, with 4-sided stems, opposite pinnately veined stipulate leaves, and small white 

 flowers, in dense axillary and terminal clusters. Calyx-tube obovoid or obconic, its limb 

 4-toothed. Corolla funnelform, 4-lobed. Stamens 4, inserted on the tube of the corolla; 

 anthers oblong or linear. Ovary 2-celled; ovules i in each cavity; style slender; stigma 

 capitate, or slightly 2-lobed. Capsule coriaceous, didymous, of 2 carpels, one dehiscent, the 

 other indehiscent. Seeds oblong, convex on the back ; endosperm horny ; embryo central ; 

 cotyledons foliaceous. [Greek, seed-point, from the sharp calyx-teeth surmounting the carpels.] 



Two or three species, natives of America. Type species : 

 Spermacoce tenuior L. 



i. Spermacoce glabra Michx. Smooth Button- 

 weed. Fig. 3925. 



Spermacoce glabra Michx. Fl. Bor. Am. i : 82. 1803. 



Glabrous, decumbent or ascending, rather stout; stems 

 io'-2o' long. Leaves lanceolate or elliptic-lanceolate, peti- 

 oled, or the uppermost sessile, i'-3' long, 4"-i2" wide, acute 

 at each end, the margins rough; corolla pubescent in the 

 throat, about \\" long, scarcely exceeding the ovate-lanceo- 

 late acute calyx teeth; stamens and style included; capsule 

 obovoid, about 2" long, glabrous; seeds black, punctate. 



On river-banks and in wet soil, southern Ohio and Ken- 

 tucky to Florida, Kansas and Texas. June-Sept. 



6. DIODIA L. Sp. PI. 104. 1753. 



Decumbent or ascending branching herbs, with opposite, mostly sessile, entire conspicu- 

 ously stipulate leaves, and small axillary white lilac or purple flowers. Calyx-tube obconic 

 or obovoid, the limb 2-4-lobed (sometimes i-6-lobed), often with minute teeth between the 

 lobes. Corolla funnelform or salverform, mostly 4-lobed. Stamens usually 4, inserted on 4 

 the throat of the corolla ; filaments slender ; anthers versatile, oblong-linear, exserted. Ovary 

 2-celled (rarely 3-4-celled) ; ovules I in each cavity; style filiform, simple or 2-cleft; stigmas 

 2. Fruit crustaceous or somewhat fleshy, oblong, obovoid, or subglobose, 2-celled, finally 

 separating into 2 indehiscent carpels. Seeds oblong, convex on the back ; endosperm horny ; 

 cotylendons foliaceous; embryo straight. [Greek, thoroughfare, where the species are fre- 

 quently found.] 



About 35 species, mostly American. Besides the following, another occurs in the Southern 

 States. Type species : Diodia virginiana L. 



Leaves linear-lanceolate ; style entire ; stigmas capitate. 

 Leaves lanceolate or oval ; style 2-cleft ; stigmas filiform. 



i. Diodia teres Walt. Rough Button- weed. 

 Fig. 3926. 



Diodia teres Walt. Fl. Car. 87. 1788. 



Spermacoce diodina Michx. Fl. Bor. Am. 1 : 82. 1803. 



Rigid, usually rough, much branched from near the 

 base, the branches prostrate or ascending, 4-sided above, 

 4'-3o' long. Leaves linear or linear-lanceolate, very 

 rough, i'-ii' long, ii"~3" wide, acute, the margins revo- 

 lute when dry ; flowers lilac or purple, 2"-^" long, usually 

 solitary in the axils ; style entire ; stigmas capitate ; fruit 

 obovoid or top-shaped, hispid, about 2" high, the usually 

 4 persistent calyx-lobes ovate to lanceolate. 



In dry or sandy soil, Connecticut to Florida, west to 

 Illinois, Kansas, Texas, New Mexico and Sonora. July- 

 Sept. Poverty-, or poor-land-weed. Poor Joe. 



1. D. teres. 



2. D. virginiana. 



