Part 1, 1918] RUBIACEAE ol 
TYPE LOCALITY: High mountains of [North?] Carolina. 
DISTRIBUTION: Mountain slopes, Virginia and West Virginia to South Carolina and western 
‘Tennessee. 
ILLUSTRATIONS: Britt. & Brown, Ill. Fl. f. 3394; ed. 2. f. 3913. 
16. Houstonia umbratilis B. L. Robinson, Proc. Am. Acad. 45: 401. 
1910. 
Prostrate perennial, the stems herbaceous, branched, glabrous, the branches very slender, 
matted, quadrangular, rooting at the nodes; stipules minute; leaves very shortly petiolate, the 
blades ovate or broadly ovate, 2.5—4 mm. long, 1.8-3 mm. wide, rounded or obtuse at the base, 
acute or acutish at the apex, green above and minutely scaberulous, slightly paler beneath and 
glabrous, 1-nerved; flowers terminal, solitary or geminate, the pedicels filiform, 1.5 cm. long; 
hypanthium turbinate; calyx-lobes lance-oblong, acute, twice as long as the hypanthium; 
corolla funnelform, about 7 mm. long, the lobes ovate; anthers exserted, linear-oblong. 
TYPE LOCALITY: Shaded cliffs of mountains near Monterrey, Nuevo Leon. 
DISTRIBUTION: Known only from the type locality. 
17. Houstonia serpyllacea (Schlecht.) C. L. Smith; Greenman, Proc. 
Am. Acad. 32: 284. 1897. 
Hedyotis serpyllacea Schlecht. Linnaea 9: 599. 1834. 
Mallostoma Shannoni Donn. Smith, Bot. Gaz. 18: 203. 1893. 
Arcytophyllum Shannoni Standley, Contr. U. S. Nat. Herb. 18: 128. 1916. 
Prostrate perennial, the stems 5—20 cm. long, stout, suffruticose, rooting at the nodes, yellow- 
ish, hirsutuious or glabrate; stipules minute, green, 1- or 2-cuspidate and glandular-ciliolate; 
leaves very shortly petiolate or subsessile, the blades oval, ovate-oval, or ovate-elliptic, 3-6 mm. 
long, 2—4.5 mm. wide, acute to rounded at the apex, rounded at the base, thick, glabrous, the 
margins usually revolute, scaberulo-ciliolate; flowers axillary, solitary, the pedicels stout, as- 
cending, equaling or shorter than the calyx and capsule; hypanthium glabrous or scaberulous; 
calyx-lobes lance-linear, 2-4 mm. long; corolla funnelform, about 1 cm. long, the lobes lance- 
triangular, acute, about as long as the tube, white-hirsutulous within; capsule oblong-obovate, 
4 mm. long, costate, about three fourths inferior, obtuse at the apex; seeds rounded-oblong, 
peltate, concavo-convex, coarsely scrobiculate. 
TYPE LOCALITY: Between La Joya and San Salvador [State of Mexico?]. 
DISTRIBUTION: Veracruz to Guatemala. 
18. Houstonia gracilis Brand. Zoe 5: 238. 1907. 
Perennial, from a stout vertical root, the stems erect or decumbent, 1—4 dm. long, slender, 
succulent, glabrous, sparsely branched, the internodes usually much longer than the leaves; 
stipules minute, setiferous; petioles slender, 2-4 mm. long; leaf-blades broadly ovate to lan- 
ceolate, 0.6—4 cm. long, 0.5—1.5 cm. wide, rounded to acutish at the base, subobtuse to attenuate 
at the apex, thin, bright-green, often scaberulous on the upper surface when young; flowers 
loosely cymose, the pedicels slender, 3-10 mm. long; hypanthium less than ] mm. long, gla- 
brous; calyx-lobes triangular, acute, equaling the hypanthium; corolla funnelform, purplish, 4—- 
5 mm. long, glabrous outside, the lobes ovate-oblong, obtuse, shorter than the tube, puberulent 
within; capsule subdidymous, 1.5—2 mm. long, 2.5 mm. wide, subretuse, almost wholly inferior, 
the free portion glabrous; seeds flat or concavo-convex, oval, about 0.5 mm. long, black, 
minutely scrobiculate. 
TYPE LOCALITY: On rocks near Orizaba, Veracruz. 
DISTRIBUTION: Veracruz. 
19. Houstonia brevipes Rose, Contr. U.S. Nat. Herb. 1: 83. 1890. 
Erect perennial, 3-6 dm. high, from a stout perpendicular root, the stems numerous, 
copiously branched, the branches stout or slender, erect or ascending, terete, glabrous, the 
internodes longer or shorter than the leaves; stipules minute, 1—4-setiferous; leaves sessile, 
linear-filiform, 1-3.5 cm. long, about 0.5 mm. wide, acuminate, glabrous; flowers in loose cymes, 
secund on the branches, partly sessile and partly on stout pedicels 1 cm. long or shorter; hypan- 
