Arachnothryx leucophylla (Kunth) Planch.

Rondeletia leptodictya B. L. Robinson, Proc. Am. Acad. 45: 402
1910.
Shrub, 2 meters high, the branches slender, terete, reddish-brown, thinly white-tomentulose whan young, but soon glabrate; stipules linear-lanceolate, 5-10 mm. long, erect, persistent, long-attenuate, thin, brown, pilose on the margins; leaves opposite, the petioles slender, 5-12 mm. long, tomentose or glabrate, the blades broadly obovate to elliptic-oblong, 4—1 1 cm. long, 1.5-5 cm. wide, acute or obtuse at the base, abruptly acute to attenuate at the apex, with an acute tip, thin, green on the upper surface and thinly villosulous, finely reticulate, beneath loosely white-tomentose when young, glabrate in age, the costa prominent, the lateral veins 7-10 on each side, very slender, ascending at an acute angle; inflorescence terminal, the peduncles slender, 4-6 cm. long, the flowers numerous, sessile in a dense globose head; hypanthium globose, densely white-tomentose; calyx-lobes 4, subequal, linear-oblong or oblanceolate, 2 mm. long, obtuse, tomentulose outside, sericeous within, spreading or reflexed in age; corolla blood-red, the tube very slender, 12-14 mm. long, thinly arachnoid-tomentose outside, glabrous in the throat, the 4 lobes oblong, obtuse, 3-4 mm. long, spreading; style exserted.
Type locality: Banks of the Rio Petatlan, near the boundary between Michoacan and Guerrero, at an altitude of 500 meters.
Distribution: Known only from the type locality.

Rondeletia leucophylla H. B. K. Nov. Gen. & Sp. 3: 395. 1820
Rondeletia elongata Bartl.; DC. Prodr. 4: 409. 1830.
Bouvardia discolor H. & A. Bot. Beech. Voy. 428. 1840. Not Rondeletia discolor H. B. K. 1820.
Arachnothryx elongata Planch. Fl. Serres 5: 442. 1849.
Rondeletia dubia Hemsl. Diag. PI. Nov. 28. 1879.
Rondeletia leucophylla calycosa Greenman, Proc. Am. Acad. 39: 92. 1903.
Shrub, about 1 meter high, the branches slender or stout, brown or reddish-brown, densely pilose or white-tomentose when young; stipules triangular-lanceolate or lance-subulate, 5-12 mm. long, attenuate, erect, persistent, thin, brown, pilose outside; leaves opposite, the petioles stout or slender, 2-20 mm. long, densely pilose or tomentose, the blades ovate, elliptic-oblong, lance-oblong, or narrowly lanceolate, 3-14 cm. long, 1-6 cm. wide, acute to broadly rounded at the base, acute to attenuate at the apex, thin, green above and densely pilose, beneath densely white-tomentose, with a loose tomentum, this sometimes deciduous in age, the lower surface then pilose, the costa prominent, the lateral veins slender, 6-10 on each side, subarcuate, ascending at an angle of about 45°; inflorescence terminal and axillary, cymose-paniculate, pedunculate, densely many-flowered, 4-6 cm. long and broad, the flowers sessile or subsessile; bracts elongate, linear-attenuate; hypanthium white-lanate and pilose; calyx-lobes 4, linear or oblong-linear, 3-6 mm. long, unequal, acute or attenuate, erect or spreading; corolla red, whitetomentose outside, the tube stout, 8-16 mm. long, naked in the throat, the 4 lobes oblong or rounded, 4-6 mm. long rounded at the apex, spreading; anthers short-exserted, yellow; capsule subglobose, 3 mm. long, densely white-tomentose ard pilose; seeds minute, angulate, pale-brown.
I . PE LOCALITY: Between Alto del Peregrino and Rio Papagallo, Guerrero. DISTRIBUTION: Sinaloa and Jalisco to Oaxaca.