752 RUBIACEAE (MADDER FAMILY) 



1. C. occidentalis L. Smooth ; leaves petioled, essentially glabrous, ovate 

 or lanceolate-oblong, pointed, opposite or whorled in threes, with short interven- 

 ing stipules. Swamps and along streams, s. w. N. B. to w. Ont., and south w. 

 July, Aug. Usually a shrub with us, rarely arborescent and 5 or 6 m. high. 

 (Mex., W. I.) 



Var. pubescens Raf. Branchlets and at least the lower surfaces of the leaves 

 soft-pubescent. 111. to Ga., La., and Tex. 



8. HOUST6NIA L. 



Calyx 4-lobed, persistent ; the lobes in fruit distant. Corolla usually much 

 longer than the calyx-lobes, the lobes valvate iu the bud. Anthers linear or 

 oblong. Style 1 ; stigmas 2. Ovary 2-celled. Pod top-shaped, globular, or 

 didymous, thin, its summit or upper half free from and projecting beyond the 

 tube of the calyx, loculicidal across the top. Seeds 4-20 in each cell, pitted. 

 Small herbs, with short entire stipules connecting the petioles or narrowed bases 

 of the leaves, and cymose or solitary and peduncled flowers ; these dimorphous, 

 in some individuals with exserted anthers and short included style ; in others 

 the anthers included and the style long, the stigmas therefore protruding. 

 (Named for Dr. William Houston, an English botanist, who collected in tropi- 

 cal America.) 



* Small and delicate, vernal-flowering ; peduncles l-flowered; corolla sah-er- 

 form ; upper half of the broad and someichat 2-lobed pod free ; seeds globu- 

 lar, with a very deep round cavity occupyiny the inner face. 



+- Perennial by delicate filiform creeping rootstocks or creeping stems; pedun- 

 cles filiform, 2-5 c. long. 



1. H. caerulea L. (BLUETS, IXNOCEXCE.) Glabrous ; stems erect, slender, 

 sparingly branched from the base, 0.5-2 dm. high ; leaves oblong- spatulate, 6-9 

 mm. long ; peduncle filiform, erect ; corolla light blue, pale lilac or nearly white, 

 with a yellowish eye, the straight slender long-exserted tube much longer than 

 its lobes or than those of the calyx. Moist and grassy places, N. S. to Ga., 

 w. to Ont., Wise., and Ala.; producing from early spring to midsummer its 

 delicate little flowers. 



Var. Faxonbrum Pease & Moore. Corolla white, with a prominent yellow 

 eye, the tube shorter, gradually expanding to the limb. Alpine regions, 

 White Mts., N. H. 



2. H. serpyllifblia Michx. Like the preceding species, but the filiform stems 

 prostrate, extensively creeping and rooting; leaves orbicular to ovate, 4-9 mm. 



long; corolla rather larger, and deep violet-blue. Along 

 streamlets and on mts. , Pa. to Tenn. and S. C. 



t- *- Winter-annuals, branching chiefly from the base; root 

 simple; peduncles much shorter. 



3. H. patens Ell. Stems 2 cm. to at length 1 dm. high, 

 with ascending branches and erect peduncles ; leaves spatu- 

 late to ovate ; corolla much smaller than that of no. 1, 

 violet-blue or purplish without yellowish eye, the tube longer 

 than its lobes, twice the length of the calyx-lobes. (H. minor 

 Britton.) Dry or sandy soil, Va. to 111. and Mo., s. to Ga. 

 and Tex. FIG. 913. 



4. H. minima Beck. More diffuse, commonly scabrous; 

 stems at length much branched and spreading, 2-10 cm. 

 high ; lowest leaves ovate or spatulate, the upper oblong 



913 II natens or near ' v linear ; earlier peduncles elongated and spreading 

 in fruit, the later ones short ; tube of the purplish corolla 

 not longer than its lobes or the ample calyx-lobes (3 mm. long). Dry hills, 

 s. e. la. to Tex. Mar.-May. 



