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 codonanthum S.F.Blake

Description:

Species Description - Terrestrial shrubs, prostrate and decumbent, often forming dense cushions, or erect, 0.1–1 m tall. Young branchlets ridged, ± smooth, pubescent or puberulous, the hairs eglandular, light brown, the indumentum of the mature branches similar but glabrate or puberulous. Leaves 9–12 per cm, spirally arranged, ascending; petiole 0.6–2 mm long, glabrate, the hairs eglandular; lamina elliptic or lanceolate, 0.4–1.4 × (0.1–)0.2–0.6 cm, basally attenuate or less often cuneate, marginally crenulate, apically ciliolate with eglandular hairs, apically acute or blunt-acute, adaxially glabrous or glabrate with eglandular hairs over midvein (especially in young leaves), abaxially glabrate with minute and deciduous glandular hairs, the venation obscure or hyphodromous on both sides, the midvein adaxially impressed and abaxially raised. Axillary solitary flowers and very rarely 2–3-flowered cymes; bracts 6–11, chartaceous, ovate or transverse-elliptic, 0.4–2.2 × 0.6–3.2 mm, marginally eciliate, apically obtuse, abaxially glabrous; pedicel 1.2–2.5 mm long, reduced and hidden by overlapping bracts or rarely with a portion not completely obscured, glabrous or glabrate with eglandular or glandular hairs; differentiated apical bracteoles 2, distinct, chartaceous, enveloping entire calyx tube or to part of calyx lobes, covering 36–80% of calyx, ovate, elliptic, or transverse-elliptic, 2–4.3 × 3–5.2 mm, rarely marginally ciliolate with eglandular hairs, apically obtuse, the surface softly longitudinally striate (rarely smooth in few herbarium specimens), abaxially and adaxially glabrous. Flowers 4-merous (one flower seen with a 5-merous corolla). Calyx aestivation valvate, campanulate, (4–)4.5–5.5 mm long; tube angled, (1–)1.5–2.5 mm long, abaxially glabrate with glandular hairs; limb (2.8–)3–3.5 mm long, abaxially glabrate, with eglandular or glandular hairs, adaxially glabrous; lobes triangular, (2–)2.3–3 × (1.5–) 1.9–2.7 mm, rarely marginally ciliolate with eglandular hairs, apically acute; sinuses acute (V-shaped). Corolla light green, often suffused with brick red distally or rarely completely brick red, thick-fleshy, bistratose, campanulate, (5.2–)6.7–10(–10.5) mm long, 6.5–9.5 mm diam., 6.5–9.5 mm wide at throat, abaxially glabrate with glandular hairs, adaxially glabrous; lobes (1.4–)2–3 × 2–4 mm, apically acute, adaxially rugose. Stamens 8 (10 in the 5-merous corolla), (4.7–) 5.3–7.5 mm long, included (the tips exerted in few herbarium specimens); filaments distinct, straight or rarely geniculate, broader at base, (2.8–)3.5–5 mm long, abaxially and adaxially glabrate or puberulous; anthers distinct, papillae on both thecae and tubules; thecae, (1.4–)1.6–2.1 mm long, without basal appendages; tubules 2, distinct, 1.3–2.1 mm long, dehiscing apically by oblique pores, 0.4–0.7 mm long. Ovary 4-locular; style (5.5–)6–7.7 mm long, included (exserted in few herbarium specimens). Berry white, ± spherical, 7.5–10 mm diam., the persistent calyx lobes erect or spreading, becoming succulent (at least at base), same color as mature berry; embryo white.

Distribution and Ecology - Disterigma codonanthum is known from scattered localities throughout the three cordilleras in Colombia, the Andes of Ecuador, and in Peru, where it is very rare and known only from a few collections from the north and center of the country (Fig. 19). It is mainly found at high altitudes, at 2700–3800 m, in humid, dry, grassy, or shrubby páramos and subpáramos, and less often in montane cloud forests. Flowering year-round; fruiting yearround, except for Jan, Jun, and Oct.

Discussion:

Disterigma codonanthum (Fig. 17C,D) is characterized by marginally crenulate leaves, softly longitudinally striate differentiated apical bracteoles, light green campanulate corollas often heavily suffused with brick red, adaxially glabrous, and tubules dehiscing by oblique terminal pores. The filaments of D. codonanthum are straight throughout its entire geographic range, except for Dávalos 8, León 4552, Luteyn 5757B, and Jørgensen 2177, which have flowers either with some filaments straight and others softly geniculate, or flowers with all the filaments geniculate. This polymorphism is rare in this species and it is also present in the type collection. However, because here the curvature of the filaments is soft, it is possible that geniculate filaments are observed so infrequently because the filaments are being flattened during the preparation of the herbarium specimens. This polymorphic character is of especial interest because it also occurs in D. empetrifolium (Fig. 4), a species that is thought to be closely related to D. codonanthum. These two taxa share many morphological characters with another geniculate taxon, D. pernettyoides (solitary flowers, very rarely few cymes or fascicles, similar stamens, white berries, white embryos, etc.), and the narrow-leaved collections of all of them are practically indistinguishable from each other when the flowers are sterile. Nevertheless, they can be easily distinguished when flowering, and the major differences among them are summarized in Table VIII.

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