Begonia modestiflora Kurz (1871: 296)

Pham, Van The, Dinh, Quang Diep, Nguyen, Van Canh, Trinh, Ngoc Bon, Nguyen, Duc Dinh, Nguyen, The Hien & Lin, Che Wei, 2021, Begonia of Vietnam: an updated checklist, including a new species and a new record, Phytotaxa 507 (2), pp. 144-154 : 151

Begonia modestiflora Kurz (1871: 296) . ( Figs. 4 & 5 ).

TYPE:— MYANMAR. Arracan , Baronga Island, Oct 1869 , W. S. Kurz s.n. (Lectotype, K; Isolecotype, K (designated by Hughes, 2008)) .

Begonia sootepensis Craib, Bull. Misc. Inform. Kew 1911:57 (1911) . Begonia modestiflora var. sootepensis (Craib.) Tebbitt, Begonias p. 248 (2005). Begonia yunnanensis var. sootepensis (Craib) Craib, Aberdeen Univ. Stud. 47: 96 (1912). TYPE:— THAILAND. Chiengmai, Doi Sootep, A.F.G. Kerr 785 (Lecotype, K; Isolecotypes, B, BM, E, P (designated by Hughes, 2008)).

Begonia sootepensis var. thorelii Gagnep., Fl. Indo-Chine 2:1104 (1921). Begonia yunnanensis var. thorelii (Gagnep.) Golding & Kareg., Phytologia 54(7): 499 (1984). TYPE:— LAOS. Bassac , 1866-1868, Thorel s.n. (Lectotype, P; Isolecotype, P (designated by Hughes, 2008)).

Begonia yunnanensis H.Lév., Repert. Spec. Nov. Regni Veg. 7:20 (1909). TYPE:— CHINA. Yunnan, Henry 12403 (Lectotype, E; Isolecotypes, B, BM, HBG, K, L (designated by Hughes, 2008).

Distribution and ecology:—It grows on wet humus on rock surfaces and is locally common. It can be seen growing alongside shrubs and herbaceous species such as Adiantum spp. , Impatiens spp. , mosses, Poaceae , and Selaginella spp. Despite the habitat location falling within Chu Yang Sin National Park buffer zone, the plant is threatened by habitat loss of unregulated activities such as forest farming, agricultural burning, and the impact of tourism.

Conservation Status:—More fieldwork in Vietnam is needed to give a precise evaluation of its population size and dynamics. We assess B. modestiflora to be Data Deficient.

Specimen examined:— VIETNAM. Dak Lak Province: Lak district, Yang Tao commune, Bim Bip waterfall, Chu Yang Sin National Park , evergreen lowland forests on silicate rocks, around point 12°26’00.8”N 108°15’31.1”E, at elevation 600–650 m a.s.l., 17 August 2020, Nguyen Van Canh, Nguyen Van Khuong, PVT1025 ( SGN, VNM) .

Notes:— Begonia modestiflora is a widespread species that occurs in Bangladesh, China, Thailand, Laos and Myanmar (Hughes, 2015–present; Shui et al., 2019), and hence shows considerable variation in morphology. Nguyen’s checklist ( Nguyen, 2003) listed B. minicarpa (Hara, 1972) as occuring in Vietnam, a species that is likely to be confused with B. modestiflora , as it shares a similar erect habit, ovate-lanceolate leaves, 4-tepaled staminate flowers and unequal ovary wings. It differs in being a smaller species that is endemic to the Himalayan region, and B. modestiflora can be further distinguished by its many-flowered (vs. few-flowered) inflorescences, 5 tepaled (vs. 3-tepaled) pistillate flowers and fruits twice as small. The specimen cited here clarifies B. modestiflora as native to Vietnam, rather than B. minicarpa .

Figures

FIGURE 4. Begonia modestiflora Kurz. A. Habit; B,B’. Portion of leaf, upper and lower surface; C. Stipules; D,D’. Bracts; E, E’. Staminate flower, face and side views; F,F’. Stamens, ventral and dorsal views; G,G’. Pistillate flower, face and side views; H,H’. Style and stigmatic band, dorsal and ventral views; I. Cross section of an immature capsule; J. Capsule.

FIGURE 5. Begonia modestiflora Kurz. A, B. Habit and habitats; C. Habit; D. Stem, showing stipules and petioles; E. Staminate and pistillate inflorescens, also showing bracts; F. Upper of branch; G. Staminate flower, face and back views; H. Pistillate flower, face and side views; I. Capsule and cross section of an immature capsule.