Begonia iridescens Dunn, 1920

Camfield, Rebecca & Hughes, Mark, 2018, A revision and one new species of Begonia L. (Begoniaceae, Cucurbitales) in Northeast India, European Journal of Taxonomy 396, pp. 1-116 : 47-48

Begonia iridescens Dunn [sect. Platycentrum ]

Fig. 30

Bulletin of Miscellaneous Information, Kew 1920: 110 ( Dunn 1920). – Type: India, Arunachal-Pradesh, Lalik Valley, Nov. 1911 – Mar. 1912, Burkill 37336 (lecto-: K000634615, here designated).

Citations in other publications

Burkill (1924: 289), Chauhan (1996: 175), Uddin (2007: 594), Hughes (2008: 57), Morris (2009c: 210), Dash (2010: 34).

Other material

INDIA: Arunachal-Pradesh: Bapu Mountain, Renging Camp, Nov. 1911 – Mar. 1912, Burkill 36246 (n.v.); ibid., Nov. 1911 – Mar. 1912, Burkill 36831 ( K 000634616); ibid., Nov. 1911 – Mar. 1912, Burkill 38821 (n.v.); ibid., Nov. 1911 – Mar. 1912, Burkill 37315 (n.v.); ibid., Nov. 1911 – Mar. 1912, Burkill 36673 ( K 000634617); ibid., Nov. 1911 – Mar. 1912, Burkill 36247 (n.v.); Igar Valley, Nov. 1911 – Mar. 1912, Burkill 36111 (n.v.); Lohit Valley, Shoehang to Paya, Rao 10627 (ASSAM n.v.); Pasighat, 10 Feb. 1928, Ward 7823 ( K); Taliha, Malhotra 57817 (ASSAM n.v.); Vatica Shingkeng Forest, Nov. 1911 – Mar. 1912, Burkill 36270 (n.v.).

Description

Rhizomatous, monoecious herb, 10 –15 cm high. Rhizome: ca 10 mm wide, villose, internodes 5–10 mm long. Stipules: lanceolate, 3–12 × 2–5 mm, pubescent to glabrous, persistent. Leaves: petiole 5–12 cm long, red villose; lamina ovate to ovate-orbicular, basifixed, base cordate with lobes overlapping, 7.5– 30 × 6–20 cm, asymmetric, upper surface green with blue iridescence and large silver spots between the veins, sparsely puberulous all over, underside green, pubescence on veins only, venation palmate, midrib 5–21 cm long; margin entire to undulate, with dense hairs; apex acute. Inflorescences: cymose, terminal, few; peduncle densely pilose, branching 3–4 times, primary 3–8 cm, secondary 2–4 cm, tertiary and quaternary 1–2 cm, with 5– 6 female and 5– 12 male flowers; bracts lanceolate, 3–6 × 1–2 mm, glabrous, margin pilose, persistent. Male flower: pedicel 10–26 mm long, sparsely pilose; tepals 4; outer tepals broadly ovate, 9–17 × 6–9 mm, pink, pilose on reverse, margin entire; inner tepals linear to spathulate, 6–12 × 3–5 mm, pink, glabrous; androecium with 15–25 stamens, asymmetric; filaments 1–3 mm long, unequal, fused at base; anther oblong-elliptic, 2–2.5 mm long, dehiscing through slits running nearly the entire length of the anther, not hooded, connective not extended. Female flower: pedicel 8–14 mm long, pilose; bracteoles absent; tepals 4–5, unequal, obovate to oblong elliptic, outer tepals 10–15 × 5–10 mm, pink, pilose on reverse, margin entire, inner tepals as in male flowers; ovary 2-locular, placentae bifid, capsule obovoid, sparsely pilose, one long oblong wing and two short triangular wings; styles 2, convoluted with slightly twisted ends, persistent. Fruit: recurved; capsule obovoid, 8–10 × 6–8 mm, sparsely red tomentose; wings not extending along pedicel, unequal; longest wing rounded oblong, 8 × 3 mm; shortest wings crescent shaped, 1–2 × 3–4 mm.

Distribution and phenology

Arunachal-Pradesh; also in Myanmar; 500–1550 m. Flowering: January to February; fruiting: February to March.

Conservation status Least Concern. Begonia iridescens has a small AOO of 28 km 2 and an EOO of 4,630 km 2, but this

is likely to reflect the very low collection density of the area. There is plenty of suitable habitat in the mountains of Arunachal-Pradesh and Northern Myanmar. The status is considered here as Least Concern.

Remarks

The leaves vary considerably in size, and are usually only 2–3 per plant, if a third is present it is often smaller. Burkill’s notes on the type specimen state the leaves lie flat against the substrate. The name refers to the blue iridescence of the upper leaf surface, also noted in B. xanthina which otherwise differs considerably in having yellow flowers and more acuminate leaf tips. A blue iridescence can also be observed on the underside of dried specimens.