BS 55 189 New insights into the diversity of the Flora of Vietnam

Jacinto C. Regalado, Jr., Nguyen Tten Hiep, Phan Ke Loc, Leonid Averyanov and Daniel K. Harder

Regalado, Jr., J. C., Nguyen, Tien Hiep, Phan Ke Loc, Averyanov, L. & Harder, D.K. 2005. New insights into the diversity of the Flora ofVietnam. Biol. Skr. 55: 189-197. ISSN 0366-3612. ISBN 87- 7304-304-4.

The flora ofVietnam has an estimated 12,000 vascular plant species, of which 10,000 have already been identified and cataloged. The proportion of endemics has been variously reported between 30% nationwide to as high as 50% in northern Vietnam. The centers of plant diversity are the Hoang Lien Son Range, the Truong Son Range (Annamites), and the Tay Nguyen Plateaus (Cen­ tral Highlands). The high level of biodiversity can be attributed to a high degree of environmen­ tal heterogeneity for climate, soil, landscape and topography. Great progress in botanical explo­ rations and scientific investigations in Vietnam during the past few years have brought new insights into the diversity and patterns of complexity of the flora ofVietnam. After the sweeping economic reforms that ended the country’s isolation, Vietnamese botanists have sought foreign technical assistance and have actively collaborated with colleagues abroad in the study of Viet­ nam’s flora, which has resulted in numerous and exciting plant discoveries. In the past decade alone (1993-2003), more than 200 new taxa, including 13 genera, of vascular plants have been described. At least 100 records of plants new to Vietnam have been similarly documented. These findings accounted for a remarkable 3% increase in the known flora. Significant increases in numbers of known new taxa were made in the Orchidaceae, Myrsinaceae, Araceae, and Euphor- biaceae.

Jacinto C. Regalado, Jr., Missouri Botanical Garden, RO. Box 299, St. Louis, MO 63166, U.S.A. E-mail: jack. regalado@mobot. org

Nguyen Tien Hiep, Department of Botany, Institute of Ecology and Biological Resources, NCST, 18 Hoang Quoc Viet Road, Cau Giay, Hanoi, Vietnam. E-mail: [email protected]

Phan Ke Loc, Faculty of Biology, Vietnam National University, 90 Nguyen Trai St., Thanh Xuan, Hanoi, Vietnam. E-mail: pkeloc@yahoo. com

Leonid V. Averyanov, Komarov Botanical Institute of the Russian Academy of Sciences, Prof. Popov St. 2, St. Petersburg 197376, Russia. E-mail: [email protected]

Daniel K. Harder, Arboretum of the University of California, 1156 High St., Santa Cruz, CA 95060, U.S.A. E-mail: dkharder@cats. ucsc.edu 190 BS 55

Introduction ably diverse flora for a relatively small country like Vietnam. The ten largest families in this Vietnam is considered as one of the most bio­ flora are Orchidaceae (897 species), Fabaceae logically diverse countries in the world and it is (557 species), Poaceae (467 species), Euphor- widely recognized that the country has a glob­ biaceae (416 species), Rubiaceae (395 species), ally significant proportion of rare and endemic Cyperaceae (304 species), Asteraceae (291 species of plants and animals. In the past species), Latiraceae (245 species), Fagaceae decade, Vietnam stunned the world with the (211 species) and Acanthaceae (177 species). discovery of three previously unknown large The flora of Vietnam is not only large, but mammals: the small dark muntjac {Muntiacus also rich in endemic species, adding to its sig­ truongsonensis), giant muntjac {Megamuntiacus nificance. The proportion of endemics has vuquangensis) and saola {Pseudoryx nghetinhen- been variously recorded, ranging from 20% sis). A number of preliminary estimates (Tol­ (Poes 1965) to as high as 50% (Thai Van Trung machev 1974; Nguyen Tien Hiep 1997; Phan 2000). A more conservative estimate (Vo Quy Ke Loc 1998) offer figures of about 9600 1995) suggests that about 10% of species and indigenous species of vascular plants in Viet­ 3% of genera are endemic to Vietnam. Among nam. In addition, about 750 naturalized, intro­ 305 vascular plant families reported for Viet­ duced and cultivated species occur in Vietnam. nam, the highest levels of endemism are An estimated 2400 additional species are observed in the Acanthaceae, Anacardiaceae, expected to be discovered and added to the Annonaceae, Apocynaceae, Araceae, Are- flora. The total number of species of vascular caceae, Asclepiadaceae, Celastraceae, Eri­ plants known in Vietnam for the time being is caceae, Euphorbiaceae, Fagaceae, Myrsi- about 10,350 species in 2,256 genera and 305 naceae, Rubiaceae, Sapindaceae, Sapotaceae, families (Phan Ke Loc 1998). This is a remark­ Theaceae and Zingiberaceae (Schmid 1974;

Year 2002. BS 55 191

Table 1. New genera for Vietnam described from 1993-2003.

Family Genus Place of Publication Orchidaceae Zeuxinella Aver. Averyanov & Averyanova, Updated Checklist of the Orchids of Vietnam, p. 96 (2003) Orchidaceae Vietorchis Aver. & Averyanova Averyanov & Averyanova, Updated Checklist of the Orchids of Vietnam, p. 92 (2003) Polypodiaceae Caobangia A.R. Sm. & X.C. Zhang Smith & Zhang, Novon 12: 546-550 (2002) Cupressaceae Xanthocyparis A. Farjon & T.H. Nguyen Farjon et al., Novon 12: 179-189 (2002) Araliaceae Metapanax]. Wen & D.G. Frodin Wen & Frodin, Brittonia 53: 117 (2001) Rubiaceae Rubovietnamia D.D. Tirvengadum Tirvengadum, Biogeographica 74: 166 (1998) Rubiaceae Vidalasia D.D. Tirvengadum Tirvengadum, Biogeographica 74: 164 (1998) Rubiaceae Fosbergia D.D. Tirvengadum & C. Sastre Tirvengadum 8c Sastre, Biogeographica 73: 88 (1997) Zingiberaceae Distichochlamys M.F. Newman Newman, Edinburgh J. Bot. 52: 65 (1995) Araliaceae Grushvitzkya N.T. Skvortsova & L.V. Averyanov Skvortsova & Averyanov, Bot. Zhurn. (Moscow & Leningrad) 79(7): 108 (1994) Asclepiadaceae Vietnamia P.T. Li Li, Journal of South China Agricultural University 15(4): 72 (1994) Poaceae Vietnamochloa J.F. Veldkamp & R. Nowack Veldkamp & Nowack, Bull. Mus. Natl. Hist. Nat., B, Adansonia 16(2-4): 214 (1995) Orchidaceae ChristensoniaJ.R. Haager Haager, Orchid Digest 57: 40 (1993)

Takhtajan 1986; Rundel 1999). A recent inven­ try is predominantly mountainous. Three tory of the orchid species in Vietnam showed quarters of the country consists of hills, that endemicity of the family is 20% plateaus and mountains that extend up to (Averyanov & Averyanova 2003). 3,000 m above sea level. The Truong Son (Annamite) mountain ranges form the natural boundary with Laos and Cambodia. The Causal factors of plant diversity mountains in the northern border with China Geography. Vietnam is situated on the eastern are extensions of the mountain systems of seaboard of Southeast Asia, bordered by China southeast Yunnan and Guangxi (Averyanov in the north, Laos and Cambodia in the west, 1990; Rundel 1999). the Gulf of Thailand in the south, and the Topography. The mountain areas fall super­ South China Sea in the east. The country has ficially into three distinct regions: 1 ) the moun­ an area of 329,566 km2, its territory spreads tains of northeastern Vietnam, 2) the Hoang more than 2,000 km from north to south, Lien Son Range of northwestern Vietnam, between latitudes 8°30’N and 23°25’N. The which represents a southern extension of the country has an elongated S-shapc with broad Himalayas, and 3) the long Truong Son (Anna­ deltas of the Song Hong (Red) River in the mite) Range which forms the backbone of north and the Mekong River in the south, Southeast Asia along the western border of linked by a narrow central section. The coun­ Vietnam (Schzeglova 1957; Rundel 1999). In 192 BS 55 the northwest of the country are the largest to high pressure regularly occurring during mountain formations of the Indochina penin­ winter in the centre of Asia over the plains of sula with the highest peaks in the region - Fan Mongolia. Basically these winds are cold and Si Pan (3143 m), Ta Giang Pinh (3096 m), Si dry. Precipitation is low during this period. Lung (3076 m), Luong (2985 m), Phuong Monsoon winds from the south and southwest Chang (2825 m), Lang Kung (2817 m) and a dominate in Southeast Asia from April to Sep­ number of others. The central mountain chain tember. These winds come from the Indian is dissected by relatively level plateaus, where and Pacific oceans where high pressure areas average elevations are mostly from 500 to 1500 are formed during summer. Basically monsoon m above sea level. The Dak Lak and Plei Ku winds are warm and wet. They bring to the con­ Plateaus, along with the Lam Vien (Dalat) tinent hot and rainy weather (Schzeglova 1957; Plateau, are sometimes collectively referred to Fridland 1961; Phan Ngoc Toan & Phan Tat as the Tay Nguyen Plateau (Central High­ Dac 1993). At the same time the complicated lands). The UNEP World Conservation Moni­ orography and specific configuration of the toring Centre (United Kingdom) considers the coast line of Vietnam locally shift direction of Hoang Lien Son Range, the Truong Son monsoon winds, change times of dry and rainy Range (Annamites) and the Tay Nguyen seasons and influence the amount of precipita­ Plateau (Central Highlands) as the centers of tion. This results in incredibly diverse climatic plant diversity in Vietnam. patterns in the country. Other distinctive geomorphologic areas of Six main basic types of climate are defined for the country are coastal plains and wide alluvial Vietnam in recent climatologie studies (Nguyen valleys of the Mekong and Red Rivers. Irregu­ Khanh Van et al. 2000). These types are classi­ lar coastal flat plains with minimal elevations fied as: 1. Monsoon tropical climate with cold above sea level connect the fertile river valleys winter, summer rains; 2. Monsoon tropical cli­ of northern and southern Vietnam by a narrow mate with cool winter, summer-autumn-winter belt coming along the coast line. The two rains; 3. Monsoon tropical climate with summer largest rivers of Southeast Asia, namely the rains; 4. Monsoon tropical climate with autumn­ Song Hong (Red) and Mekong Rivers, create winter rains; 5. Monsoon sub-equatorial climate wide alluvial delta regions in Vietnam. Both with summer rains; and 6. Monsoon tropical cli­ these regions represent large flat delta plains mate associated with mountains. covered by alluvial deposits of Quaternary age. Geology. Generally mountain systems in The Song Hong River delta has an area of Vietnam are composed of silicate rocks, mainly more than 15,000 km2 while that of the granite, gneiss, rhyolite or quartzite, which Mekong extends over 40,500 km2 covering were formed by extensive magmatic intrusions much of the lowlands of southern Vietnam. in the late Paleozoic and Mesozoic (Dovzikiv et Rich alluvial soils in each of the delta regions al. 1965a, b). Tertiary tectonic movements have enabled these areas to evolve as major uplifted these mountain terrains to current population centres based on their agricultural elevations and subsequent erosions formed productivity. More than 80% of the population modern characteristic rocky landscape (Schze­ live in territories of coastal and delta plains, glova 1957; Rundel 1999). Ancient highly while the mountain regions still have a very metamorphosed limestone from which devel­ sparse human population. oped karst is typical and widely distributed in Climate. North and northeast winds domi­ the northern part of the country. To the east nate in the region from October to March, due the mountains gradually give way to vast allu­ BS 55 193 vial plains. For excellent reviews of the geologi­ areas with more arid conditions these forests cal history of Vietnam and the Indochina give way to open, semi-deciduous and decidu­ region, refer to the following literature: Schze- ous broad-leaved savanna-like woodlands. glova (1957), Fridland (1961), Dovzikiv et al. Along semi-desert coastal plains and on arid (1965b) and Rundel (1999). sea slopes of southern Vietnam woodlands Historical Biogeography. The uplifting of develop their shrubby derivatives, which often the Himalayas over the last 10MY formed an appear as a more or less dense sclerophyll effective barrier to the exchange of species scrub. Swampy grass-sedge communities and between Palaearctic and Indo-Malayan realms. mangrove thickets are common on flat coastal This barrier, reinforced by increased climatic plains especially in deltas of large rivers. All cooling after the Miocene, isolated Indo­ types of native primary vegetation have been Malaya and created conditions for species destroyed in many parts of the country. Sec­ divergence. Recent relatively stable equatorial ondary forests, shrubs and grasslands, bamboo conditions combined with dynamic geological thickets, tree plantations, pastures, crop and changes allowed isolated populations to vegetable fields, and different weed communi­ diverge further, thus contributing to the enor­ ties have replaced most native vegetation in mous species richness and high levels of Vietnam. endemism that now characterize the region The eight main types of plant cover are: 1. (MacKinnon & MacKinnon 1986). Evergreen broad-leaved forests on alkaline Vietnam lies on the crossroad of interchange soils; 2. Evergreen and semi-deciduous broad­ between the floristic elements of the south­ leaved, mixed and coniferous limestone moun­ eastern Himalayas and Indo-Malaysia. The tain forests; 3. Evergreen lowland forests on sil­ Hoang Lien Son mountains in the northwest of icate rocks at 0 - 1000 m elevation; 4. Ever­ the country form an extension of the Henduan green montane and highland forests on silicate mountains of China and are floristically related rocks at 1000 - 3000 m elevation; 5. Semi- to southwest China. The mountains to the east deciduous dry lowland forests; 6. Deciduous of the Red River are connected to the lime­ dry lowland forests and savanna-like wood­ stone ranges of Guangxi and show close affini­ lands; 7. Coastal vegetation, lowland wetlands ties to the flora of southern China (Nguyen and mangrove thickets; 8. Secondary, weed Nghia Thin & Harder 1996). In the west, the and agricultural plant communities, wood and Truong Son Range forms a partial barrier industrial plantations (Averyanov et al. 2003). between the moist uplands of Vietnam and the drier monsoon forests of Laos, and it traverses the transition zone between the tropical mon­ Phytogeographic units soon climate with cool winters in the north and Up until recently, available data on geology, cli­ the tropical Indo-Malayan south. mate, flora and vegetation of Vietnam were rather poor for even preliminary phytogeo­ graphic generalizations in the eastern part of Vegetation Indochina. As a result, only highly schematic Tropical monsoon forests are the most com­ and abstract floristic divisions of the area were mon kind of vegetation in Vietnam. Wet closed proposed in consideration of modern phyto­ evergreen broad-leaved, mixed or coniferous geography of mainland Southeast Asia (Good forests are found in mountain regions. At the 1964; Takhtajan 1978, 1986; Wu & Wu 1998). same time in some hilly lowland and valley Recent botanical explorations in Vietnam dur- 194 BS 55 ing the last ten years have revealed consider­ Cyperaceae, Euphorbiacae, Ericaceae, able new knowledge on this area. The analysis Fagaceae, Lamiaceae, Lauraceae, Moraceae, of modern literature and recent data on geol­ Orchidaceae, Poaceae, Pteridophyta, Rubi- ogy, geomorphology, climate, flora and vegeta­ aceae, Urticaceae, and Zingiberaceae. Recently tion give possible preliminary delineation of Vietnamese botanists have started writing the main phytogeographic units in the eastern part Flora of Vietnam in their own language. The first of Indochina. four volumes: Annonaceae (Nguyen Tien Ban Six floristic units may be outlined on the ter­ 2000), Lamiaceae (Vu Xuan Phuong 2000), ritory of Vietnam and adjacent areas of the Cyperaceae (Nguyen Khae Khoi 2002), and eastern part of Indochina. Some preliminary Myrsinaceae (Tran Thi Kim Lien 2002) have borders of these areas as floristic province were already been published. outlined in the general floristic division of Our incomplete understanding of the flora Takhtajan (1978, 1986). The six defined floris­ of Vietnam is based on older, unverifiable data tic provinces with more or less defined borders and a paucity of research collections support­ are: 1. Sikang-Yunnan Province; 2. South Chi­ ing adequate biogeographic and taxonomic nese Province; 3. North Indochinese Province; studies. A large number of forest inventories 4. Central Annamese Province; 5. South and checklists have been produced based on Annamese Province; 6. South Indochinese field observations and literature alone. This Province (Averyanov et al. 2003). methodology typically overlooks many species, especially in taxonomically difficult or unpub­ lished groups, and as a result there are no reli­ Studies on the Flora of Vietnam able estimates of the numbers of threatened Our understanding of the flora of Vietnam, species or total number of species in the coun­ albeit incomplete, is attributed to several fun­ try. All credible botanical inventories must rely damental taxonomic publications, such as Flora on high-quality, fully documented vouchers of Cochinchinensis (Loureiro 1790, 1793), Flore all vascular and non-vascular plants. Générale de V Indo-Chine (Lecomte & Humbert Perhaps Loureiro gathered the first collec­ 1907-1951), Flore du Cambodge, du Laos et du Viêt- tions of herbarium specimens in Vietnam Nam (Aubréville et al. 1960-2001), An illustrated before 1790. Mostly French collectors, such as flora of Vietnam (Pham Hoang Ho 1991-1993), Balansa, Chevalier, Eberhardt, Harmand, Vascular plant synopsis of Vietnamese flora Pételot, Pierre, Schmid, Thorel, Vidal, and (Averyanov et al. 1990, 1996) and a number of especially Poilane, collected a majority of the large recent floristic and taxonomic studies. extant specimens during the first four decades Analyses of the systematic structure of the flora of the past century. Estimates of the number of have been done by Phan Ke Loc (1998) and Le collections made by these botanists is around Tran Chan (1999). 75,000 with a majority of the specimens The flora of Vietnam is being written, in deposited in the herbarium at the Laboratoire French, as part of the regional flora Flore du de Phanérogamie, Muséum National d’His- Cambodge, du Laos et du Viet Nam, but the toire Naturelle in Paris (P) and several thou­ progress has been slow. From 1960-2001, 74 sands duplicates kept in the Herbaria of the families have been published, which comprise Institute of Tropical Biology in Ho Chi Minh only 26% of the total number of families in City (HM) and the Department of Botany of Vietnam. Most major groups have not been Vietnam National University in Hanoi (HNU). revised, including Acanthaceae, Asteraceae, After 1945, Vietnam was racked by warfare for BS 55 195 many years, with little botanical exploration in records for the flora of Vietnam. These discov­ the country since French colonial times. After eries added 306 species to the flora of Vietnam, the sweeping economic reforms in the 1990s contributing to a 3% increase in the known that ended Vietnam’s isolation from the world flora (Table 2). Significant gains in numbers of since 1975, Vietnamese botanists have sought new taxa were made in the Orchidaceae (63 foreign technical assistance and have actively species), Myrsinaceae (34 species), Araceae collaborated with their colleagues abroad in (27 species) and Euphorbiaceae (15 species). the study of Vietnam’s flora. International The most spectacular findings are the new cooperative agreements were made with the genera and species of a cupressoid conifer, following institutions: Missouri Botanical Gar­ Xanthocyparis vietnamensis (Farjon et al. 2002) den (U.S.A.), Komarov Botanical Institute and the polypodiaceous fern, Caobangia squa- (Russia), Royal Botanic Gardens, Kew (U.K.), mata (Smith & Zhang 2002). The Vietnam National Herbarium of New South Wales (Aus­ Golden Cypress {Xanthocyparis vietnamensis) is tralia), Singapore Botanic Gardens (Singa­ the fourth new conifer described since 1948, pore), Kunming Botanical Institute (China), after Metasequoia, Cathaya and Wollemia. The and with international conservation organiza­ unusual species bears both juvenile needles tions working in Vietnam, namely, world Con­ and mature scale leaves on the same branches servation Union (IUCN), World Wildlife Fund of mature trees. This species closely resembles (WWF), and Fauna and Flora International the Nootka Cypress {Chamaecyparis nootkatensis (FFI). These research initiatives have resulted = Xanthocyparis nootkatensis) of western North in additional specimens using modern collec­ America, reflecting ancient links between east­ tion methods and have contributed signifi­ ern Asia and western North America. On the cantly to our knowledge of the rich flora of other hand, Caobangia is one of two fern gen­ Vietnam. Over the past ten years, international era recently described. The discovery of a new botanical teams have conducted surveys in 22 genus of ferns based on new collections is an provinces. More than 15,700 collection num­ uncommon event. In 2001 a new fern genus bers with 78,500 duplicate specimens were col­ was described from Korea but previous to that, lected. Duplicates were distributed to AAU, K, the last such new genera were described in the L, MO and P. late 1960’s.

Recent discoveries

A survey of the botanical literature, using the Table 2. Summary of discoveries for Vietnam flora from online version of the Kew Records of Taxo­ 1993-2003. nomic Literature (http://www.rbgkew.org.uk/ kr/KRHomeExt.html), showed a dramatic Plant Groups New species & New species increase in the number of publications on the infraspecific taxa records Vietnam flora in mid-1990’s when the interna­ Ferns 1 10 tional cooperative activities were initiated (Fig­ Cycads 10 8 ure 1 ). These collaborative efforts have Conifers 5 5 resulted in numerous and exciting plant dis­ Dicots 106 12 coveries. Thirteen new genera (Table 1) and Monocots 107 42 229 new species and infraspecific taxa were described from 1993-2003, including 77 new Total: 229 77 196 BS 55

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