Heterostemma beddomei (Hook.f.) Swarupan. & Mangaly,

Heterostemma beddomei (Hook.f.) Swarupan. & Mangaly, View in CoL

Bot. J. Linn. Soc. 101(2): 254. 1989. Oianthus beddomei Hook.f., Fl. Brit. View in CoL India 4(10): 49. 1883.

Lectotype (designated by Rodda, 2016): INDIA, Kerala (Mysore state, 1862), Wyanad district, Beigoor forests ( Begur Reserve Forest ), 04.08.1862, ex Beddome s.n. ( K, drawing). Fig. 1 View Fig

Twining vine, about 3 m long, with milky white latex in all vegetative parts. Roots wiry, branched. Stem slender, cylindrical, pubescent and/or with two opposite longitudinal lines of hairs. Leaves decussate, chartaceous when dry; lamina ovate or broadly or narrowly ovate-lanceolate or ovate-cordate, 6–14 × 2–6 cm, apex acuminate, base cordate or obtuse, 3–7-nerved from base, ciliolate along margins, veins pubescent or not, glabrous; petiole 1.5–3.5 cm long, grooved, sparsely pubescent on grooves or glabrous. Inflorescence extra-axillary, umbellate cymes; cymes initially single (peduncle 4–6 mm long, pubescent) and later 2–4 cymes borne along the rachis (rachis 1–2.5 cm long, pubescent); each cyme 4–12 (20–30)-flowered; pedicels 3–4.3 mm long, pubescent or with one or two longitudinal lines of hairs present. Bracts minute, triangular, deciduous. Calyx lobes connate at base, tube 0.2– 0.4 mm long; lobes ovate or triangular or ovate-lanceolate, 1−1.5 × 0.6−1 mm, apex obtuse. Corolla depressed globose, disciform, 9−9.6 mm in diam., white or yellowish-white or dark pink, hairy on inner surface and glabrous or rarely pubescent on outer surface; tube 7–8 mm long; lobes short, broadly triangular, 1.8−2.3 × 1.9−2.1 mm, fleshy, apex obtuse and slightly recurved. Gynostegium sessile, cupular in outline, 4–4.8 mm in diam. Staminal corona lobes 5, inserted at the base of the stamens, erect, connate at the base, fleshy, dark pink or yellow, reniform, 1.9–2.2 mm long, 2–2.3 mm wide, apex spreading and sparsely crenate on margins; pollinaria 5, erect; pollinium ovoid or ellipsoid, c. 0.2 × c. 0.14 mm mm, yellow, with sub-apical germination crest, attached to the short and hyaline caudicles, laterally slightly above the base; corpusclum oblong, reddish brown. Ovary ovoid, 2–2.5 mm long, glabrous; stigma conical or pentagonal. Follicles 2, diverging, terete, 6–14 cm long, tapering towards apex. Seeds many, broadly ovate to orbicular, 8–10 mm in diam.; coma silky white.

Flowering & fruiting: Flowering from September to October and fruiting from late September to December.

Habitat: It grows in blackish-red soils of dry deciduous forests at elevations between 500–900 m.

Distribution: Endemic to South India.

Specimens examined: INDIA, Telangana, Nagarkurnool district, Amrabad Tiger Reserve , Lingala area ,about 550m, 03.09.2018, B.Sadasivaiah & A. Ramakrishna 3549 ( CAL, TBGH); Amrabad Tiger Reserve , Mannanur range, Pullayapally, about 860 m, 12.12.2020, B. Sadasivaiah & A. Ramakrishna 4325 ( TBGH); Mannanur range, Gundam base camp, about 840 m, 23.10.2021, K. Prasad 5253 ( BSID) .

Conservation status: Heterostemma beddomei is a narrow endemic species, hitherto known only from Kerala and doubtfully from Karnataka ( Jagtap & Singh, 1999). In India, many publications focussing on threatened species do not include this species, and it has not been given any conservation status ( Henry et al., 1979; Jain & Sastry, 1984; Nayar & Sastry, 1987, 1988, 1990; Rao et al., 2003). This species was first collected by Beddome in 1862, and the present collections are made in 2018, 2020 and 2021. The time gap between these collections is more than 150 years from its first collection and it is now recorded in four restricted locations in the Eastern Ghats (Telangana) and Western Ghats (Kerala). In the present study, we have noticed more than 100 individuals of Heterostemma beddomei , occurring in three nearby locations in the Eastern Ghats of the Amrabad Tiger Reserve and further explorations in the earlier documented locations are necessary to ascertain the extend of its extant populations. Currently, as per the IUCN guidelines ( IUCN, 2022), the species is assessed here as ‘Data Deficient’ (DD).

Notes: No herbarium material of Heterostemma beddomei exists, and the only extant original material is a drawing by Beddome (K). The drawing, which gives scanty information and does not depict all the characters, leads to misidentifications of the species. Heterostemma beddomei is very similar to H. disciflorum , having common morphological characters: twining habit, corolla lobes short and triangular without any inner appendages. However, H. beddomei has ovate or broadly or narrowly ovate-lanceolate or ovate-cordate leaves with acuminate apex and cordate or obtuse base (vs. elliptic-oblong to ovate-oblong, sub-acute apex, sub-cordate base in H. disciflorum ), calyx lobes ovate-lanceolate, ovate or triangular (vs. oblong), and corolla inner surface hairy (vs. glabrous).