Begonia dioica Buch.

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 : 35-37

Begonia dioica Buch. -Ham. ex D.Don [sect. Diploclinium]

Figs 22–23

Prodromus Florae Nepalensis: 223 ( Don 1825).

– Type: Nepal, Kathmandu, Naraianhetty , 8 Aug. 1802, Buchanan-Hamilton (lecto-: BM000043986 , here designated).

Begonia tenella D.Don , Prodromus Florae Nepalensis: 223 ( Don 1825).

– Type: Nepal, Gosain Than, 3000–4830 m, 1821, Wallich Cat. No. 3681B (lecto-: K-W, barcode K001110783 , here designated) .

Begonia amoena Wall. ex A.DC., Prodromus Systematis Naturalis Regni Vegetabilis 15 (1): 327 (de Candolle 1864).

– Type: Nepal, 1821, Wallich Cat. No. 3682A (lecto-: K-W, barcode K000761417 , here designated ).

Begonia erosa Wall., A numerical list of dried specimens of plants in the East India Company’s Museum: 129, 3688 ( Wallich 1831), nom. nud.

Citations in other publications

As B. dioica: Hara (1975: 85) , Hara et al. (1979: 181), Grierson (1991: 241), Kumar (2002: 644), Uddin (2007: 593), Dash (2010: 33); as B. tenella: de Candolle (1864: 327) , Ghazanfar & Aziz (1976: 3); as B. amoena: Fischer (1938: 97) .

Other material examined

INDIA: Arunachal-Pradesh: Dirang Dzong, 8 Aug. 1938, Ward 14055 ( BM); Senge Dzong, 18 Aug. 1938, Ward 14091 ( BM). Mizoram: Hmuifang, Jul. 1926, Parry 45 ( K); ibid., Jul. 1926, Parry 46 ( K); ibid., Jul. 1926, Parry 47 ( K); Lungleh, 1 Sep. 1931, Wenger 320 ( K).

Description

Tuberous, creeping, stoloniferous, dioecious herb, 5–11 cm high. Stolons: red, glabrous, slender, 5–15 cm long. Stipules: lanceolate, 3–4 × 1–2 mm, glabrous, caduceus. Leaves: petiole 1–5 cm long, glabrous; lamina deltate-ovate, basifixed, base shallowly cordate, 3–12.5 × 1.5–7 cm, symmetric, upper surface green with red veins or red centre, glabrous, underside red, glabrous, venation palmate, midrib 2.5–12 cm long; margin crenate to dentate, glabrous; apex acuminate. Inflorescence: cymose, terminal, few; peduncle glabrous, branching up to three times, primary 5–10 cm long, secondary and tertiary 3–5 mm long, with 2– 5 female flowers or 3– 5 male flowers; bracts lanceolate 4–5 × 2 mm, glabrous, caduceus. Male flower: pedicel 10–25 mm long, glabrous; tepals 4; outer tepals ovate-orbicular, 6–15 × 5–10 mm, pink to deep pink, glabrous, margin entire; inner tepals elliptic, 4–8 × 2–4 mm, white to pale pink, glabrous; androecium with 15–20 stamens, symmetric; filaments 1–2 mm long, unequal, fused at base into a short column; anther obovate, 1 mm long, dehiscing through short slits near the tip, not hooded, connective not extended. Female flower: pedicel 17–20 mm long, glabrous; bracteoles absent; tepals 2–3, unequal, outer two elliptic-ovate, third lanceolate, 8–15 × 3–10 mm, white to pink, glabrous; ovary 3-locular, placentae bifid; capsule ellipsoid, glabrous, with three equal rounded triangular wings; styles 3, deeply forked once and twisted once, persistent. Fruit: pendulous; capsule ellipsoid, 10 × 6 mm, glabrous; wings equal, rounded-triangular, wings 3–6 × 7–8 mm.

Distribution and phenology

Arunachal-Pradesh; also in northern Pakistan, northern India, Nepal, Sikkim and Bhutan; 1350–1850 m. Flowering: July to September; fruiting: August to October.

Conservation status

Least Concern. Begonia dioica has an AOO of 204 km 2 and an EOO of 344,000 km 2 with plenty of suitable habitat throughout its range in the Eastern Himalayas and Arakan Mountains. This species is also present in several National parks in Nepal and Bhutan along with the Lengteng Wildlife Sanctuary and Blue Mountain National Park of Mizoram.

Remarks

Distinctive characters for B. dioica are the persistent tepals on the maturing fruit, and the bright red/ crimson stolons, petioles and peduncles. Begonia labordei is the closest ally in the study area, which differs in having more denticulate leaves and more congested inflorescences; the fruits of B. dioica are further distinctive in having equal, rounded wings.

Figures

Fig. 22. Map showing the location of B. dioica Buch.-Ham. ex D.Don specimens.

Fig. 23. Photograph showing habit and female flowers of B. dioica Buch.-Ham. ex D.Don. Photograph courtesy of Sangeeta Rajbhandary of a plant in Nepal.