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Family:

Ericaceae (Magnoliophyta)

Primary Citation:

Mem. New York Bot. Gard. 29: 149, fig. 75H-R. 1978

Accepted Name:

This name is currently accepted.

Type Specimens:

Specimen 1: Holotype -- J. A. Steyermark

Description:

Description: Shrub 0.5-1.5(-3) m tall; mature stems terete, glabrous; twigs subterete, bluntly angled, smooth, glabrous. Leaves in whorls of 3-4, strongly imbricate, appressed to spreading, linear- to oblong-elliptic, or elliptic to ovate, (3.2-)4.5-7 x 1-1.5(-2.0) mm, base broadly cuneate, decurrent, apex acute, strongly keeled, provided with a sessile, ± triangular, red to black, callosed, terminal gland (apex with additional 4-7 tiny, triangular, reddish, sessile to short-stipitate glands which may fuse), apparent margin glabrous to minutely ciliate; petiole subterete, 0.5-2.0 mm long, glabrous. Inflorescence axillary, flowers 2-4; pedicels subterete, striate, ca. 10-13(-20) mm long, densely puberulent to short-white-pilose (with a few, short, reddish, apex minutely branched, eglandular setae ca. 0.2 mm long, or also glandular-hispid with hairs to 1 mm long); floral bract and bracteoles undifferentiated from leaves. Flowers 7-8-merous; calyx 4.5-8 mm long, lobes wide-spreading, linear-ovate, leaf-like in appearance, 4-7 mm long, acuminate, essentially glabrous or puberulent dorsally but margins minutely white-ciliate, with glands as in leaves (without apical, sessile gland but instead eglandular-mucronate, or nearly entire margin provided with tiny, sessile, ± triangular glands); petals spreading (corolla ± rotate), oblong-obovate, 10-15 mm long, rounded, margin ± erose, deep red to scarlet when fresh, glabrous; stamens ca. 5-5.2 mm long; filaments 3-3.5 mm long; anthers 1.8-2.5 mm long; ovary glabrous; style 2-3 mm long, glabrous. Capsule to 5 mm long.

Distribution: Endemic to Venezuelan Guayana and known only from the Chimantá Massif, where it is found in a variety of habitats including thickets and Bonnetia forest, shrub islands and on open rocks in savannas, and rocky sandstone slopes along streams, at elevations of (1850-)1920 to 2500 m. Flowering and fruiting specimens have been collected from Jan to Jun. This species may hybridize with L. luteus and L. decumbens. A sterile twig on a sheet containing mostly L. guyanensis (Holst 3728, MO) appears to be L. atroadenus--it is from Aparaman-tepui which lies about 25 minutes latitude north of Chimantá and would be the first collection outside of the Massif.

Type: Venezuela. Bolívar: Chimantá Massif, Abácapa-tepui, NW part of summit, 2125-2300 m, 13 Apr 1953 (fl, fr), Steyermark 74886 (holotype, NY; isotypes, F, photo F neg. 59488, US, photo NY neg. 12208, VEN). A second sheet of this number at F (#1739232) is L. luteus.

Flora and Monograph Treatment(s):

Ledothamnus atroadenus Maguire, Steyerm. & Luteyn: [Article] Luteyn, James L., et al. 1995. Ericaceae, Part II. The Superior-Ovaried Genera (Monotropoideae, Pyroloideae, Rhododendroideae, and Vaccinioideae P.P.). Fl. Neotrop. Monogr. 66: 560.
Ledothamnus atroadenus Maguire, Steyerm. & Luteyn: [Article] Maguire, Bassett. 1978. The botany of the Guayana Highland--part X. Mem. New York Bot. Gard. 29: 1-288.