Monographs Details: Sipanea pratensis var. dichotoma f. glabriloba Steyerm.
Authority: Maguire, Bassett. 1967. The botany of the Guayana Highland--Part VII. Mem. New York Bot. Gard. 17: 1-439.
Family:Rubiaceae
Description:Species Description - A var dichotoma f dichotoma atque aliis corollae lobis omnino glabris 5-11 mm longis 3-7 mm latis recedit; praeterea hypanthio plerumque parce vel breviter pubescenti plerumque basi vel apice glabro; calvcis lobis 3-6 mm longis 0.3-0.8 mm latis; capsulis parce vel breviter pubescentibus; caulibus parce adpresso-pubescentibus glabris; foliorum laminis supra glabris vel parce pubescentibus subtus plerumque glabris nisi costa media nervis lateralibusque pilis brevibus adpressis instructis differt.

Distribution and Ecology - VENEZUELA. Amazonas: abundant along Yavita-Pimichin trail near Yavita, Rio Atabapo, alt 125-140 m, 10 .Tun 1959, suffrutescent, sprawling to 1 m, flowers pale pink, John J. Wurdack & Lincoln Adderley 42016 (holotype NY); San Carlos, Rio Negro, alt about 100 m, Holt & Gehriger 329; San Carlos, Rio Negro, alt about 100 m, Holt & Blake 640; alrededores de Yavita, Alto Orinoco, alt 128 m, Williams 14147; en terrenos arenosos abiertos, Yavita, alt 128 m, Williams 13876; Rio Autana, afluente del Sipapo, Cruxent 53; Piedra Catipan, alt 100-140 m, Maguire, Wurdack A Bunting 36474; bare slopes of Piedra Nunca (just N of Piedra Cucuy), Rio Negro, alt 200-250 m, Maguire & Wurdack 34951; around laja at mouth of Cano Arapacua, Rio Pacimoni, alt 120 m, Maguire & Wurdack 34918; on white sand in scrub savanna at Yavita, alt 130 m, Maguire 29319; Bolivar: exposed granitic outcrops along hills bordering Rio Toro (Rio Grande) between Rio La Reforma and Puerto Rico, north of El Palmar, Sierra Imataca, alt 200-250 m, Steyermark 87966. BRITISH GUIANA. River bank between laterite rocks, Orinduile Falls, Ireng River, alt ca 600 m, Harrison 1377; sandy dike, East Coast. Water Conservancy, SE of Georgetown, canal SE of Lamaha Stop-off, Hitchcock 16981; Rockstone, Gleason 703; sandy or rocky ground, savannas, Kaieteur Plateau, Maguire & Fanhawe 23472.

Discussion:

The longer and broader corolla-lobes, broader calyx-lobes, and more open and elongated inflorescence distinguish this form from the other forms of S. pratensis var dichotoma having glabrous corolla-lobes. This form resembles the leaf-shape in most respects of 5. pratensis var dichotoma, but is closer to var pratensis in the greater glabrity of the hypanthium, capsule, and corolla-lobes.