Part 1, 1918] RUBIACEAE 33 
capsule; corolla 12-16 mm. long, the tube slender-funnelform, glabrous, the lobes ovate, 8 
mm. long or shorter, acute, sometimes less than half as long as the tube and sometimes two 
thirds as long, white-villosulous within; capsule subglobose, 2.5 mm. long, about two thirds 
inferior, shallowly bisulcate, rounded or slightly retuse at the apex, densely hirtellous; seeds 
crateriform, 0.8 mm. long, black, minutely roughened on the back. 
TYPE LOCALITY: High prairies, from Live Oak Creek to Las Moras, western Texas. 
DISTRIBUTION: Western Texas to Coahuila and San Luis Potosi. 
23. Houstonia polypremoides A. Gray, Proc. Am. Acad. 21: 379. 
1886. 
Houstonia polypremoides Bigelovii Greenman, Proc. Am. Acad. 32: 291. 1897. 
Erect shrub, 1-2 dm. high, fruticose below, the stems usually very numerous and much 
branched, stout, minutely scaberulous or densely hirtellous, the internodes usually longer than 
the leaves, sometimes shorter; stipules about 0.5 mm. long, mostly bicuspidate; leaves opposite, 
sessile, the lowest linear-oblong, the upper ones acerose-linear, rigid, 5-12 mm. long, scaberu- 
lous or hirtellous, rarely glabrate, the margins revolute; flowers solitary, axillary and terminal, on 
stout pedicels 13 mm. long or shorter; hypanthium very short, scaberulous or hirtellous; calyx- 
lobes lance-subulate, 3-4 mm. or rarely 1.5-2 mm. long, scaberulous, in fruit usually longer 
than the capsule; corolla salverform, white, 8-11 mm. long, the tube slender or stout, ampliate 
above, glabrous outside, the lobes oblong-ovate, about two thirds as long as the tube, obtuse or 
acutish, white-villous within; capsule subglobose, 2.5-3 mm. long, broadly rounded or subre- 
tuse at the apex, densely hirtellous; seeds crateriform, with a short hilar ridge, black. 
TYPE LOCALITY: Santa Eulalia Mountains, Chihuahua. 
DISTRIBUTION: Dry, rocky hillsides, western Texas, southern New Mexico, and Chihuahua. 
24. Houstonia fasciculata A. Gray, Proc. Am. Acad. 17: 203. 1882. 
Erect shrub, 1-4 dm. high, fruticose throughout, much branched, the branches stout, 
ascending, grayish, brown, or blackish-brown, the branchlets whitish, angulate, scaberulous 
or minutely hirtellous, densely leafy; stipules minute, setulose-denticulate; leaves opposite 
or 3- or 4-verticillate, usually with dense fascicles of leaves in the axils, sessile, 3-10 mm. long, 
linear or nearly so, bisulcate on the lower surface, acute, mucronulate, scaberulous or glabrate; 
flowers in small dense few-flowered short-pedunculate terminal cymes, on very short pedicels; 
hypanthium about 1 mm. long, scaberulous; calyx-lobes triangular-ovate, about as long as 
the hypanthium, obtuse; corolla white, 3-4 mm. long, salverform, the lobes recurved, pilose 
within; capsule oval-ovoid, 2.5 mm. long, about half inferior, obtuse at the apex, compressed, 
shallowly bisulcate, very scabrous; seeds about 1 mm. long, oblong, peltate, concavo-convex, 
black, minutely scrobiculate. 
TYPE LOCALITY: Presidio, Texas. 
DISTRIBUTION: Dry, rocky hillsides, western Texas and southern New Mexico to Coahuila. 
25. Houstonia angustifolia Michx. Fl. Bor. Am. 1: 85. 1803. 
Houstonia rupestris Raf. Ann. Gén. Sci. Phys. 5: 226. 1820. 
Hedvyotis stenophylla T. & G. Fl. N. Am. 2: 41. 1841. 
Hedyotis lasiantha Nutt.; A. Gray. Pl. Wright. 1: 81, assynonym. 1852. 
Oldenlandia angustifolia A. Gray, Pl. Wright. 2: 68. 1853. 
Oldenlandia angustifolia filifolia A. Gray; Chapm. Fl. S. U.S. 181. 1860. 
Houstonia angustifolia scabra S. Wats. Proc. Am. Acad. 18: 97. 1883. 
Houstonia angustifolia filifolia A. Gray, Syn. Fl. N. Am. 12: 27. 1884. 
Houstonia angustifolia rigidiuscula A. Gray, Syn. Fl. N. Am. 12: 27. 1884. 
Houstonia salina A. Heller, Bot. Expl. Tex. 96. 1895. 
Houstonia pulvinata Small, Bull, N. Y. Bot. Gard. 1: 289. 1899. 
Houstonia tenuis Small, FI. SE. U.S. 1109. 1903. 
Houstonia rigidiuscula Wooton & Standley, Contr. U. S. Nat. Herb. 16: 175. (1913. 
Plants perennial, the stems few or numerous, erect, ascending, or procumbent, 1-6 dm. 
long, subsimple or much branched, the branches stout or slender, quadrangular, glabrous, the 
internodes longer or shorter than the leaves; stipules whitish, scarious, 3 mm. long or shorter, 
usually deltoid, cuspidate, laciniate or setiferous; leaves sessile or nearly so, linear or oblan- 
ceolate-linear to filiform, 1-5 cm. long, 0.5-5 mm. wide, acute or acutish at the apex, mucro- 
nulate, usually attenuate to the base, thin or thick and firm, 1-nerved, usually scaberulous or 
