![]() |
(A) Begonia glabritepala Souvann. et Lanors. (B) B. heteracantha Souvann. et Lanors. (C) B. lanxangensis Souvann. et Aver. (D) B. parviglandulosa Souvann. et Lanors. (E) B. pseudobrandisiana Souvann. et Lanors. (F) B. tripartifolia Souvann. et Lanors.
in Souvannakhoummane, Lanorsavanh & Averyanov, 2021. Photographs by S. Lanorsavanh (A, B, D–F) and K. Souvannakhoummane (C). |
Abstract
New species of Begonia L. in the flora of Laos presented in this paper were mainly found in the course of botanical surveys made in Hin Nam No National Protected Area, Nam Phouy National Protected Area, Khammouane Karst Forest, and Phou Khao Khouay National Protected Area.Additionally, herbaria presently available in Laos (HNL, FOF, NUoL, FRC), living plants, and alcohol preserved material at Pha Tad Ke Botanical Garden and the data accessible online at BM, E, K, LE, NY, P, and PE Herbaria were critically studied. The study conducted during 2012–2019 reveals seven new species for science and seven species newly recorded for the flora of Lao PDR.
Species described as new for science are: Begonia glabritepala (found in Khammouane Province; it is most close to B. pierrei but differs in glabrous outer tepals of staminate flowers, pistillate flowers, capsules, petioles, peduncles and pedicles), B. heterocantha (found in Sainyabuli Province; most close to B. depingiana but differs in reddish purple, glandular pubescent abaxial leaf surface, glandular pubescent pedicel, and outer tepals of pistillate flowers sparsely white glandular pubescent), B. lanxangensis (found in Vientiane Province; most close to B. paleacea but differs in elongate tubers, ovate-lanceolate, obscurely asymmetrical to symmetrical leaves, and glabrous pedicels), B. parviglandulosa (found in Vientiane Province; most close to B. martabanica but differs in smaller habit, reniform-cordate leaves and glandular indumentum on peduncle, pedicle and capsules), B. pseudobrandisiana (found in Khammouane Province; most close to B. brandisiana but differs in pistillate flowers with five elliptic-oblanceolate tepals), B. tripartifolia (found in Khammouane Province; most close to B. tricuspidata but differs in leaves palmate triangular-ovate, with deeply lobed lacerate margin, pistillate flower of five tepals, and ovary with unequal wing), and B. viriditenebris (found in Khammouane Province; most close to B. sinuata but differs in single leaf, indumentum of bristle hairs and reddish or bronzy green adaxial leaf surface, and three styles).
The following species discovered and recorded for the flora of Laos at first are: B. hatacoa (known in Nepal, Bhutan, NE India, Myanmar, Thailand, and Vietnam), B. hemsleyana (China, Vietnam), B. labordei (NE India, Myanmar, S China, Vietnam), B. longifolia (tropical zone from NE India to Indonesia), B. minuscula (Vietnam), B. parvula (S China), and B. subperfoliata (Myanmar, Thailand, S Vietnam). Descriptions and line drawings are provided for all newly described species. Photographic illustrations, data on phenology, habitat, and notes on morphological variations and relations are given for all studied species.
Keywords: local endemism, new species, plant diversity, plant taxonomy, Indochine
![]() |
Begonia glabritepala Souvann. et Lanors.: A – Flowering plant in natural habitat, flowers and capsule. B. heteracantha Souvann. et Lanors.: B – Flowering plant in natural habitat, flower and capsules.
B. lanxangensis Souvann. et Aver.: C – Flowering plants in natural habitat. B. parviglandulosa Souvann. et Lanors.: D – Flowering plants in natural habitat, pistillate flowers and capsule.
B. pseudobrandisiana Souvann. et Lanors.: E – Flowering plant in natural habitat, inflorescence and pistillate flower. B. tripartifolia Souvann. et Lanors.: F – Flowering plant in natural habitat and flowers.
Photographs by S. Lanorsavanh (A, B, D–F) and K. Souvannakhoummane (C). |
Begonia glabritepala Souvann. et Lanors., sp. nov.
(B. sect. Reichenheimia (Klotzsch) A. DC.)
Diagnosis. The species is similar to B. pierrei Gagnep. in habit but differs in having glabrous outer tepals of staminate flowers, pistillate flowers, capsules, petioles, peduncles, and pedicles (vs. all mentioned plant parts pilose) (Fig. 1, 2A).
— The specific epithet refers to glabrous tepals.
Distribution. This species is endemic to Hin Nam No National Protected Area (Khammouane Province, Boualapha District).
Ecology and phenology. Wet rock crevices in humid places of limestone deciduous forest. Flowers from August to October, fruits in October.
Vernacular name. Som Saeng Pha (hill begonia).
Begonia heterocantha Souvann. et Lanors., sp. nov.
(B. sect. Lauchea (Klotzsch) A. DC.)
Diagnosis. This species is close to B. depingiana Y. H. Tan et H. B. Ding in its tuberiferous habitus, distichous alternate leaves, and 3-locular ovary (Hong-Bo et al., 2020b). From mentioned species, it differs in reddish purple, glandular pubescent abaxial leaf surface (vs. abaxial surface light green, densely white villous), glandular pubescent pedicel (vs. pedicel puberulous), and outer tepals of pistillate flowers sparsely white glandular pubescent (vs. tepals almost glabrous, light pinkish) (Fig. 2B, 3).
— The specific epithet refers to dorsal wing of capsule that looks like broad spine.
Distribution. Endemic to Nam Phouy National Protected Area (Sainyabuli Province, Thongmixai District).
Ecology and phenology. Wet sandy soil in deciduous forest mixed with bamboo. Flowers in September, fruits in October.
Vernacular name. Som Koung Khao Dang (white speckled begonia).
![]() |
Begonia lanxangensis Souvann. et Aver.:
A -Flowering plant; B -staminate flower, frontal view; C, DPistillate flowers, frontal and side views; E -Ovary, cross section; F -Style and stigmatic bands; G -Anthers, lateral, dorsal and ventral views.
Scale bars: A -2 cm; B-F -1 cm; G, H -1 mm. Drawn by K. Souvannakhoummane. |
Begonia lanxangensis Souvann.
et Aver.,
sp. nov. (B. sect. Monophyllon A. DC.)
Diagnosis. This species is closest to B. paleacea Kurz in having inflorescences arising from the base of the leaves, but it differs in having elongate tubers (vs. tubers globose), ovate-lanceolate, obscurely asymmetrical to symmetrical leaves (vs. leaves distinctly asymmetrical, ovate to orbiculate), and glabrous pedicels (vs. pedicels glandular pubescent) (Fig. 2C, 4).
— The species epithet refers the old name of Lao PDR, which means “Kingdom of million elephants”, as well as Phou Khao Khouay National Protected Area is one of a few elephant habitats still existing in the country.
Distribution. Known only from type locality at Phou Khao Khouay National Protected Area (Vientiane Province).
Ecology and phenology. Moist mossy rocks in seasonally dry evergreen forest mixed with bamboo on the hill slopes. Flowers in May – June.
Vernacular name. Som Koung Lane Xang (million elephant begonia).
Begonia parviglandulosa Souvann. et Lanors., sp. nov.
(B. sect. Parvibegonia A. DC.)
Diagnosis. The plant is most similar to B. martabanica A. DC. but differs in smaller habitus, reniform-cordate leaves (vs. leaves ovate), peduncle, pedicle and capsules with glandular hairs (vs. pubescent with simple hairs) (Fig. 2D, 5).
— The specific epithet refers characteristic glandular indumentum.
Distribution. Endemic of Phou Khao Khouay National Protected Area (Vientiane Province).
Ecology and phenology. Moist mossy rocks in seasonally dry evergreen forest mixed with bamboo near stream. Flowers in July – October, fruits in October – November.
Vernacular name. Som Koung Noi (weed begonia).
Begonia pseudobrandisiana Souvann. et Lanors., sp. nov.
(B. sect. Reichenheimia (Klotzsch) A. DC.)
Diagnosis. The new species is similar to B. brandisiana Kurz but differs in pistillate flowers having five tepals (vs. pistillate flowers with two tepals), outer pairs of tepals of both staminate and pistillate flowers elliptic-oblanceolate (vs. tepals orbiculate) (Fig. 2E, 6).
— The specific epithet refers to the superficial similarity of the new species with Begonia brandisiana.
Distribution. This species known only from Tham Nang Ene Cave Preserved Area (Khammouane Province, Thakheak District).
Ecology and phenology. Rock on limestone hills covered by deciduous forest in association with Globba sp., Zingiber sp., Impatiens sp., and Argostemma sp. Flowers in June – August, fruits in July – September.
Vernacular name. Som Koung Bai Dok Thong (butea leaf begonia).
Begonia tripartifolia Souvann. et Lanors., sp. nov.
(B. sect. Reichenheimia (Klotzsch) A. DC.)
Diagnosis. The species is similar to B. tricuspidata C. B. Clarke from B. sect. Alicida C. B. Clarke but differs in having leaves palmate triangular-ovate, with deeply lobed lacerate margin (vs. leaves ovate with almost entire or crenate margin), pistillate flower with five tepals (vs. pistillate flowers with four tepals), ovary with unequal wings, dorsal wing smaller, triangular, lateral wings broadly lunate (vs. ovary with subequal wings) (Fig. 2F, 7).
— The specific epithet means deeply lobed, mainly tripartite leaves.
Distribution. Endemic of Mahaxay Karst Area (Khammouane Province, Mahaxay District).
Ecology and phenology. Limestone rocks on wet slopes in open forest or scrub in association with Microchirita sp., Argostemma sp., and Adiantum sp.
Vernacular name. Som Koung Bai Seak (deeply lobe-leaved begonia).
![]() |
Begonia viriditenebris Lanors. et Souvann.: A – Flowering plant, flowers and capsule. B. hatacoa Buch.-Ham. ex D. Don: B – Flowering plant in natural habitat and staminate flowers.
B. hemsleyana Hook. f.: C – Flowering plants in natural habitat and pistillate flowers. B. labordei H. Lév.: D – Inflorescence with staminate and pistillate flowers.
B. longifolia Blume: E – Pistillate flower. B. minuscula Aver.: F – Flowering plants in natural habitat, inflorescences and rhizomes. Photographs by S. Lanorsavanh (A, C–D) and K. Souvannakhoummane (B, E–F). |
![]() |
Begonia viriditenebris Lanors. et Souvann.:
A -Flowering plant; B, C -Pistillate flowers, frontal and side views; D, E -Staminate flowers, frontal and side views; F -Ovary, cross section; G -Style and stigmatic bands, side view; H -Stamens, dorsal and side views; I -Capsule, lateral view.
Scale bars: A -2 cm; B-F, I -5 mm; G-H -1 mm. Drawn by K. Souvannakhoummane. |
Begonia viriditenebris Lanors. et Souvann., sp. nov.
(B. sect. Parvibegonia A. DC.)
Diagnosis. This new species is similar to B. sinuata Wall. ex Meisn. but differs in single leaf, indumentum of bristle hairs and reddish or bronzy green adaxial leaf surface (vs. two-three leaves, indumentum of stellate hairs and dark green adaxial surface of leaf), three styles (vs. two styles), and glandular hairy pedicels (vs. pedicels with stellate hairs) (Fig. 8, 9A).
— The specific epithet means the bronzy-green leaf color.
Distribution. Endemic to Tham Nang Ene Cave area (Khammoune Province, Thakheak District).
Ecology and phenology. Wet limestone and granite rock in association with Asplenium sp., Adiantum sp., Globba sp., and Zingiber sp. Flowers in June – August, fruits in September – October.
Vernacular name. Som Koung Tham (cave begonia).
Keooudone Souvannakhoummane, Soulivanh Lanorsavanh and Leonid V. Averyanov. 2021. Seven New Species and Seven New Records of
Begonia L. (Begoniaceae) in the Flora of Laos.
Turczaninowia. 24(2); 99-119. DOI:
10.14258/turczaninowia.24.2.12
