Monographs Details – Ericaceae

Monographs Details:

Authority:

Pedraza-Peñalosa, Paola. 2010. (Ericaceae, Vaccinieae). Fl. Neotrop. Monogr. 108: 1-126. (Published by NYBG Press)

Family:

Ericaceae

Scientific Name:

Disterigma pallidum A.C.Sm.

Description:

Species Description - Epiphytic or terrestrial shrubs, erect, 0.75–3 m tall. Young branchlets ridged, ± smooth, puberulous, the hairs eglandular or glandular, white, the indumentum of the mature branches similar but glabrate. Leaves 2–4 per cm, apparently distichous, diffuse; petiole 1.6–3.6 mm long, glabrate, the hairs eglandular or glandular; lamina elliptic or at times ovate, 0.9–1.8 × 0.47–0.95 cm, basally obtuse or cuneate, marginally entire, slightly revolute toward the base, apically ciliolate with eglandular hairs (especially in young leaves), apically obtuse and shortly apiculate, sometimes acute or obtuse, adaxially glabrate with eglandular hairs, abaxially glabrate with glandular hairs, the venation adaxially hyphodromous with the midvein impressed, abaxially obscure. Axillary solitary flowers and rarely 2-flowered fascicles; bracts 4–6, chartaceous, ovate, 0.7–1.6 × 0.7–1.6 mm, marginally eciliate, apically obtuse or acute, abaxially glabrous; pedicel 0.7–1.3 mm long, reduced and hidden by overlapping bracts, glabrate with glandular hairs; differentiated apical bracteoles fused by one of their lateral margins into 1, very rarely a couple of flowers with 2 differentiated apical bracteoles, chartaceous, enveloping entire calyx tube or sometimes just the base of the calyx tube, covering 29–50% of calyx, ovate or transverse-elliptic, (1.3–)1.5–3.4 × (2–)3–4.6 mm, marginally ciliolate with eglandular hairs, apically obtuse and emarginate, or obcordate, the surface smooth with 1–2 diffuse keels, abaxially and adaxially glabrous. Flowers 4- merous. Calyx aestivation valvate, cylindric, (4.7–) 5.5–7.5 mm long; tube terete, 2.4–3.1 mm long, abaxially glabrate with eglandular or glandular hairs; limb 2.8–4.9 mm long, abaxially glabrate with eglandular hairs, adaxially glabrous; lobes triangular, 1.6–2.8 × 0.9–1.8 mm, marginally eciliate, apically acuminate and drying darker; sinuses rounded (U-shaped). Corolla bright pink, thick-fleshy, bistratose, tubular, (9.9–)11.9–15 mm long, 3–3.6 mm diam., 2.1–2.5 mm wide at throat, abaxially and adaxially glabrous; lobes 1.7–2.4 × 1.1–2 mm, apically acute, adaxially smooth. Stamens 8, (8.7–)11–13.5 mm long, included; filaments distinct, straight, ± linear with parallel sides, (6.7–)8.7–11 mm long, abaxially glabrous, adaxially glabrate distally; anthers distinct, papillae on both thecae and tubules; thecae (1.5–)1.9–2 mm long, without basal appendages; tubules 2, distinct, (1.1–)1.4– 1.7 mm long, dehiscing introrsely by longitudinal slits, (0.8–)1–1.3 mm long. Ovary 4-locular; style 12–13 mm long, exserted. Berry purple, ± spherical, 5–6.7 mm diam., the persistent calyx lobes erect or spreading, becoming succulent (at least at base), same color as mature berry; embryo color unknown.

Distribution and Ecology - Disterigma pallidum is endemic to Dept. La Paz, Bolivia, at the area of Cotapata-Coscapa-Chuspipata, on both the new and old roads to Coroico, and the valley of the river Zongo (Fig. 36). This species is found at 2950–3500 m in montane cloud forests ("ceja de montaña") or in the transition to humid puna ("yungas"). It is frequently associated with Sphagnum and has been recorded growing in both primary and secondary vegetation, as well as along roadsides. Flowering in Jan–Jul and Nov–Dec; fruiting in Mar–Apr and Nov.

Discussion:

Disterigma pallidum is easily distinguished because it has only one differentiated apical bracteole as a result of the fusion of the original pair by one of their ends; the resulting bracteole has the apex emarginate or obcordate. Rarely, flowers with two distinct differentiated apical bracteoles (a handful among all examined specimens) can be found. Disterigma pallidum (Fig. 34D) can also be characterized by its apparently distichous leaves, with the apex obtuse and shortly apiculate; calyces with the apex of the lobes often drying darker and with rounded sinuses; long, tubular, and bright pink corollas; and purple berries. In the original description, it is incorrectly mentioned that the flowers have two differentiated apical bracteoles. Also, flowers were described as smaller than those here observed; the dimensions of the original description are here within parenthesis as the lower range of the measurements. Although Disterigma pallidum has a distinctive combination of characters and can be singled out because of its bracteoles, it superficially looks like a small-leaved form of D. alaternoides or D. humboldtii, two species that are less frequent in the central Andes where D. pallidum grows. Disterigma pallidum can be easily differentiated from D. alaternoides and D. humboldtii because its corollas are bright dark pink (vs. white to light pink in the other species) and because it has longer calyces ([4.7–]5.5– 7.5 mm vs. [2.5–]3.5–5.5 mm), corollas ([9.9–]11.9–15 mm vs. [5.2–]7–9[–10] mm), and stamens ([8.7–]11– 13.5 mm vs. [4.5–]5–7[–8] mm).

Distribution:

Bolivia South America| La Paz Bolivia South America|

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