166 ON SOUTH-AMERICAN APOCYNACEX. 
lanceolate, fleshy, glabrous, with revolute margins, 4-2 in. long, 25-5 lines broad ; racemes 
axillary, on a very long naked peduncle, bearing 1 or more flowers ; sepals short; corolla 
hypocrateriform, with a long, narrow, cylindrical tube, swollen a little below the mouth; 
segments rotate, roseate red; disk of 2 orbicular lobes. 
PRESTONIOPSIS. 
This is a very good genus, established by Müller, in 1860, upon the Echites pubescens 
of Willdenow (non Hook.), one of Humboldt's plants, the exact locality of which was not 
known; but this I find is Bogota. The plant was first noticed by Willdenow, under a 
short account stating that it had an axillary subumbellate inflorescence. Müller has 
given a copious floral character of it from a specimen stated to be incomplete ; my ex- 
amination of Mutis's plant confirms the correctness of Müller's details in every particular. 
He observes that, although it offers a slight resemblance to Prestonia in habit and ag- 
gregated flowers, it is very dissimilar in its floral structure; and he points to Laseguea 
as its nearest ally. According to my view, the genus must be placed in the Dipladeniee, 
on account of its bilobed disk. In habit it approaches Wicradenia ; and in the small size 
of its flowers it offers some similarity to Homaladenia. The calyx consists of 5 narrow, 
very acuminate sepals of unequal length, quincuncially imbricate, and furnished within 
with a basal, bidentate scale; the tube of the corolla is cylindrical, as long as the sepals, 
and narrowed at its base for a quarter of its length; segments as long as the tube, 
narrowly oblong, and erect, dextrorsely convolute in «estivation ; stamens seated at the con- 
striction of the tube; filaments short, glabrous, affixed toa tuft of white hairs in the sinus 
of the anthers; anthers sublinear, with an apical membrane, and shortly cordate at the 
base, cohering in a cone by their agglutination to the clavuncle; disk of 2 broadish, flat, 
opposite lobes, shorter than the 2 free ovaries; a short style surmounted by a very thick 
5-grooved clavuncle, indusiate at its base by a narrow membrane; stigmata 2, short and 
terminal; 2 follicles, subulately terete, rather stout, subdivaricate; seeds many, subu- 
lately terete, with a very erect apical coma nearly twice its length. 
1. Prestoniopsis PUBESCENS, Müller, Bot. Zeit. 1860, p. 22, tab. 1 (in parte infer.) figs. 1-6; id. Linn. 
xxx. p. 439: Echites pubescens (non Hook. & Arn.), Willd. in R. € Sch. iv. p. 796; Kunth. Nov. Gen. 
iii. 453; A. DC. Prodr. viii. 476. In Nova Granada: v. s. in herb. Mus. Brit. Bogotá (Mutis). 
This is said to be a scandent shrub; its branches are somewhat stout, lenticellately 
verrucose, pubescent, compressed, and dilated at the nodes by a transverse ridge ; axils 
2-3 in. apart; leaves opposite, subpatent, oblong-ovate, cordate at the base, acutely 
acuminate, darkish green above, with immersed nerves, pubescent, yellowish opake be- 
neath, nerves prominent, 33 in. long, 12 in. broad, on pubescent petioles 5 lines long; 
inflorescence axillary, on a peduncle 93 lines long; flowers very numerous, in a subcapi- 
tate head, on pedicels obsoletely pilose, 3 lines long, each with 2 acute bracts 13 line long; 
sepals linear-lanceolate, very acuminate, unequal in length, 4-5 lines long, quincuncially 
imbricate, pilose outside, with an internal, bidentate, linear scale; tube of corolla 
