Monographs Details: Mesechites acutisepala Monach.
Authority: Maguire, Bassett & Wurdack, John J. 1958. The botany of the Guayana Highland--Part III. Mem. New York Bot. Gard. 10: 1-156.
Family:Apocynaceae
Description:Latin Diagnosis - Frutex scandens gracilis; foliis oppositis chartaceis non nitidis; petiolis 5-15 mm longis; laminis laneeolatis, 4.5-11 cm longis, 1.5-3 cm latis, ad basin obtusis vel subrotundatis, ad apicem acuminatis; nervis secundariis principalibus utroque 10-15 paene rectis, prope marginem arcuatis; venis tertiariis obscuris, glandulis ad basin laminae 2 vel 4, pectinatis; floribus aggregatis; pedicellis usque ad 6 mm longis; lobis calicis lanceolatis ca. 4-5 mm longis, ad apicem angustatis acutisque; tubo corollae 1.5 cm longo (floribus nondum expansis), extus glabro, intus insertio staminum pubescenti; lobis corollae (in alabastro) 4.5 mm longis; staminibus ca. medio tubi corollae insertis; antheris 4 mm longis glabris, lobis basilaribus obtusis; ovario glabro; nectarinis 5.

Species Description - Slender vine, the stem glabrous or sparsely puberulent-hirtellous, moderately lenticelled, the nodular appendages inconspicuous, deltoid, less than 0.5 mm long, easily lost; leaves opposite, chartaceous, dull; petiole 5-15 mm long, channelled above; blades lanceolate, obtuse to subrounded at the base, acuminate at the apex, 4.5-11 cm long, 1.5-3 cm wide, faintly puberulent along the midrib, the principal secondary nerves about 10-15 pairs diverging from the midrib almost at right angles and straight for a considerable distance before arching near the margins, tertiaries faint; glands at the base of the blade 2 or 4, pectinate, conic,, up to 1 mm long; flowers greenish, clustered at the apex of an axillary peduncle 2-9 cm long, the pedicel up to 6 mm long; calyx-tube about 1.7 mm long, squamellae within at the apex to about halfway down the tube, the calyx-lobes oblong or deltoid-lanceolate, narrowed and acute at the apex, 4-5 mm long, ciliolate; corolla pale pink below, salverform, the throat slightly dilated, the tube 1.5 cm long (flowers not expanded), glabrous outside, pubescent at the insertion of the stamens within, the corolla-lobes dextrorsely contorted, 4.5 mm long (in bud) ; stamens inserted at about middle of the corolla-tube, the anthers 4 mm long, glabrous; nectaries 5, concrescent at the base.

Discussion:

Figure 16

Type: Bassett Maguirc, R. S. Cowan d' John J. Wurdack 29488, Rio Cunucunuma, Rio Orinoco, Amazonas, Venezuela, at landing, Playa Alta, Nov 9, 1950, vine, flowers greenish, lower one-third of corolla pale pink (unicate, NY).

M. acutisepala is characterized by the acute lobes of the calyx and the straight wide-spreading secondary nerves. The only other known South American species with acute sepals is the Colombian M. citrifolia (H.B.K.) Woodson. The leaf texture in M. acutisepala is thinner, the secondaries spread at a wider angle and are not barbate at the axils, the tertiaries are fainter, the leaf base is not subcordate; the calyx is obviously much larger than that of M. citrifolia. Our species more probably developed from the widely distributed variable M. trifida (Jacq.) Muell.-Arg.; it is easily distinguished from it by the acute calyxlobes and the more erect and straight secondary nerves.