Begonia glutinosa Kiew, 2007

Kiew, Ruth, 2007, Notes on Vietnamese Begonia (Begoniaceae), including three new species, Adansonia (3) 29 (2), pp. 229-238 : 230-232

1. Begonia acetosella Craib

Kew Bulletin Miscellaneous Information: 153 (1912);

Tebbitt Brittonia 55: 22, figs 1D, 2 (2003).

Begonia aptera auct . non Blume: Gagnepain in Lecomte, Flore générale de l’Indo-Chine 2: 1110 (1921); Hô., Cây Cô Viêt Nam 1: 729, fig. 2023 (1991), Cây Cô Viêt Nam 1: 577, fig. 2305 (1999).

MATERIAL CITED. — Mt Ba Vi, Petelot 7084 ( B, n.v.). — Sa

Pa, Sino-Vietnam team & C. Y. Wu 379 ( KUN, n.v.). —

Tam Dao, D’Alleizette s.n. ( L, n.v.). — Lang Bian, Eber-

hardt (not located).

REMARKS

This is one of the wingless berry begonias in Vietnam. Tebbitt (2003), in his revision of sect. Sphenanthera , has shown that Gagnepain’s taxon belongs to Begonia acetosella . He recognised two varieties of B. acetosella , but only var. acetosella occurs in Vietnam.

DISTRIBUTION

Vietnam (Hà Tây [Mont Ba Vi], Lâm Dông [Massif du Lang Bian], Lào Cai [Sa Pa], and Vinh Phu [Massif du Tam Dao]), Myanmar, N Thailand, Laos, and SW China.

2. Begonia glutinosa Kiew , sp. nov. ( Fig. 1 )

Begonia wallichiana auct . non A.DC.: Gagnepain in Lecomte, Flore générale de l’Indo-Chine 2: 1115 (1921);

Hô., Cây Cô Viêt Nam. 1: 743, fig. 2065 (1991), Cây Cô Viêt Nam. 1: 588, fig. 2351 (1999).

Species in fructu Begonia bonii Gagnep. optime congruens, sed habitu erecto (nec rhizomato), foliis minoribus 4-8 × 3-5 cm (nec 7-11 × 5-7 cm) et inflorescentiis brevioribus 2-3 cm longis (nec usque 20 cm) differt. Sect. Reichenheimia .

TYPUS. — Vietnam, Lang Son (Massif du Cai Kinh, route de Thanh-moi au col de Dao-ben), 5.X.1917, Bois s.n. (serres du Muséum) (holo-, P barcode P00539150 ; iso-, P barcodes P00539151 , P00539152 ) .

OTHER MATERIAL EXAMINED. — Vietnam. Lang Son (Thanh Moi), 18.VII.1916, Bois s. n . (P).

DESCRIPTION

Annual, cane-like herb densely covered in downy viscid hairs on stems, petioles, lower leaf surface, upper and lower surface of the midrib and veins, inflorescences and pedicels, in the dried state appearing minutely and densely pubescent. Rhizome short, erect stems to 50 cm tall, robust and 3-6 mm thick, internodes 2.5-5.2 cm long, nodes constricted, pale green, becoming reddish; branches c. 4.5 cm long, pale green, zigzag. Stipules caducous, lanceolate, c. 2 mm long. Leaves oblique; petioles 3-7 cm long; laminas more or less asymmetric, broadly ovate, 4-8 × 3-5 cm, basal lobe c. 2 cm long, bright green above, pale beneath, base cordate, margin shallowly dentate-crenate, apex shortly acuminate; venation palmate-pinnate with 2 pairs of veins at the base, 2 pairs along the midrib and 2 veins in the basal lobe, veins very fine, in dried state scarcely prominent beneath. Inflorescences axillary, cymose, 2-3 cm long, erect, few-flowered (with up to 3 male flowers and one female flower), protandrous, male flowers above, with a single female flower below; peduncle downy. Bracts like the stipules, lanceolate, 1-3.5 × 1.5 mm long. Flowers pale pink, pedicels 5-20 mm long. Male flowers with pedicels 10-15 mm long, tepals 4, outer two oval, c. 8 × 7 mm, outside downy with viscid hairs; the interior two narrowly obovate-linear, c. 5 × 3 mm, androphore c. 1 mm long, stamens c. 20, filaments longer than the anthers, anthers elliptic, c. 1 mm long, locules lateral, not reaching the top of the connective. Female flowers with pedicels 7-12 mm long, tepals 5, slightly glandular outside, 5-6 × 2.5-3.5 mm, the inner ones smaller than the outer ones; ovary orbicular or slightly rhomboid in outline, 12-16 × 12-13 mm, densely downy, styles 3, free, bifurcating and lyreshaped, spirally twisted at the apex. Fruits downy, oval in outline, 12-16 × 12-13 mm; wings 3, equal, 3-4 mm wide or sometimes slightly unequal with the longer wing c. 5 mm wide, very thinly fibrous with a conspicuous network of veins, locules 3, placentas 1 per locule with two short side branches, dehiscing between the locules and wings.

REMARKS

The name “ Begonia wallichiana ” has had a tortuous history and is in fact correctly applied to a Brazilian species ( Doorenbos 1975). The Himalayan species to which this name was also applied is now correctly known as B. minicarpa H.Hara ( Hara 1972) , but the latter species bears no resemblance to the Vietnamese one. It is a small begonia that grows to 22 cm tall, has lanceolate triangular leaves attenuate to the apex with a short petiole to 2 cm long. The capsule too is small (to 4 mm long) and it has unequal wings, the larger 4-5 mm wide and the smaller two 2-3 mm wide. The Vietnamese taxon is clearly not this species. It is a new species.

This is a very distinct species by the combination of its cane-like habit, its relatively small leaves and fruits with three more or less equal, rounded wings. It is the only Vietnamese begonia reported to have viscid hairs, hence the species epithet. The type was grown from seed collected by D. Bois from “Cai Kin route de Thanh-moi au col de Deo-ben” in December 1908 (last digit not clearly legible). Among the Vietnamese species with short stems to 50 cm tall that are not succulent (i.e. that excludes species in sect. Parvibegonia), it superficially resembles Begonia boisiana Gagnep. , but its leaves are much more oblique and unequal and, more importantly, it differs in its fruits that have three equal wings (in B. boisiana they are conspicuously unequal). In addition, Gagnepain (1921) considered differences in stigma morphology important – his B. wallichiana has lyre-shaped stigmas while B. boisiana has suborbicular ones. Begonia boisiana , which has fruits with three locules each with two placentas, belongs to sect. Petermannia .

In its fruits with three equal wings, three locules each with a single placenta, it falls within sect. Reichenheimia . The three other Vietnamese species in this section, B. bonii Gagnep. , B. harmandii Gagnep. and B. pierrei Gagnep. are different from this species in being stemless begonias that produce inflorescences with long peduncles from the prostrate rhizome. They also all have relatively larger and broader ovate leaves. In addition, they have different fruits – those of B. harmandii are very hairy and those of B. pierrei are inverted pyramidal in outline. Begonia bonii has similar fruits in that the wings are narrow and rounded. Indeed, in Gagnepain’s account they key out together. He contrasted the stemless, downy B. bonii without viscid hairs and lacking an androphore with his B. wallichiana , a downy viscid plant with a branching stem and a short androphore.

DISTRIBUTION

Endemic in Vietnam: Lang Son (Massif du Cai Kinh).

HABITAT

In a high valley, by streams on rocks inundated by the water flow.

Figures

FIG. 1. — Begonia glutinosa Kiew:A, habit;B, male flower;C, stigmas;D, transverse section of fruit. Bois s.n. Scale bars: A,B, 15 mm; D, 5 mm.