Arcytophyllum fasciculatum (A. Gray) Terrell & H. Rob.

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 3or 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.