Begonia palmata var. khasiana (Irmsch.) Golding & Kareg.

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 : 72-73

Begonia palmata var. khasiana (Irmsch.) Golding & Kareg.

Phytologia 54: 495 ( Golding & Karegeannes 1984). – Begonia laciniata subsp. khasiana Irmsch., Mitteilungen aus dem Institut für allgemeine Botanik in Hamburg 10: 529 ( Irmscher 1939). – Type: India, Meghalaya, Khasia mountains, Hooker & Thomson 10 (lecto-: E00265074, here designated).

Other material

INDIA: Arunachal-Pradesh: 20 Oct. 2002, Hutchinson & Cox et al. 10081 ( E). Manipur: Meebold 6395 (syn B n.v.). Meghalaya: Khasi Hills, Cherrapunji, 15 Apr. 1952, Chand 5356 ( MICH); ibid., 15 Aug. 1952, Koelz 31101A ( MICH); Khasi Hills, Mawphlang, 8 Apr. 1954, Chand 7503 ( MICH); Khasi Hills, Mawryngkneng, 18 Oct. 1951, Koelz 28876 ( MICH); ibid., 4 Sep. 1951, Koelz 28337 ( MICH); Khasi Hills, Pynursla, 17 Aug. 1949, Koelz 23516 ( MICH); Khasia, Clarke 54285B (syn B n.v.); ibid., Griffith 2560 (syn B n.v.); Khasia mountains, Hooker & Thomson 10 ( BM, K); Shillong, 2 Apr. 1965, Cox & Hutchinson 306 ( E, K).

Description

Stem: red tomentose. Stipules: 10–27 mm long, red tomentose. Leaves: petiole densely red tomentose; lamina ovate, upper surface with short red pubescence all over, denser on veins, underside red, red pubescence all over, denser on veins; several lobes, long, triangular, not curved; apex acuminate or acute.

Remarks

A very variable species which has a wide distribution throughout Eastern Asia and Indochina. The lobes on the leaf margin vary from elongate acuminate to shortly triangular. Young leaves have very dense hairs which become less dense as the leaf matures. The leaves can also bear markings (Koelz 33555) ranging from a few simple spots to larger bands of colour similar to B. annulata or B. rex , although the deeply lobed margin separates B. palmata from these two species. This species is also vegetatively very similar to B. flaviflora , which is distinguished by its smaller yellow flowers. Begonia flaviflora also has shorter stipules and the upper surface of the leaves are almost glabrous with a few sparse hairs on veins, unlike those of B. palmata which usually has bristles scattered all over leaf from sparse to very dense. The longest wing on the fruit is only 1 cm long in B. flaviflora and has a crenate tip which is not seen on B. palmata .

Begonia palmata forms a natural hybrid with B. longifolia where the two are growing together, known as Begonia × chungii ( Peng & Ku 2009; Morris 2011a). This hybrid has baccate fruit with wings, and is intermediate in form between the two parents. The leaves are deltoid and lobed like B. palmata with red margin and centre, sometimes with light green spots between the red veins.

There are several infra-specific taxa under B. palmata . Two are present in the study area, with the type variety being far more common. Begonia palmata var. khasiana is distinct for having densely red villose stems, petioles and peduncles. The upper surface of the leaves is quite rough, and feels like sandpaper to the touch when dried, due to the short bristles about 200 µm long, in B. palmata var. palmata the hairs are softer and 400–700 µm long ( Irmscher 1939).

There is potential for other varieties to be present in the study area, such as B. palmata var. bowringiana (Champ. ex Benth.) Golding & Kareg. ( Golding & Karegeannes 1984; basionym: Bentham 1852), which are recorded from nearby Yunnan. However, given the variation we see in B. palmata applying these names is extremely difficult, and may not be biologically meaningful.