Notes on the genus Argostemma (Rubiaceae) of the Malay Peninsula and Peninsular Thailand

Abstract

SUMMARYThe genus Argostemma Wall. (Rubiaceae) in the Malay Peninsula and Peninsular Thailand are discussed with regard to general morphology, distribution and ecology from studies of herbarium specimens from various herbaria together with the field surveys of the natural populations in the study area

Argostemma cordatum (Rubiaceae), a new species from Vietnam

“…Species of Argostemma typically inhabit wet, shady areas of primary (undisturbed) evergreen forests, e.g. moss-covered rock faces, stream banks and surroundings of waterfalls (Sridith & Puff 2000, Sridith 2007.…”

Argostemma glabra(Rubiaceae), a New Species from Vietnam

“…During a floristic exploration work in the HonBa Nature Reserve of Khanh Hoa Province in Vietnam, we collected an interesting species of Argostemma which after a close scrutiny of the available literature (Pitard 1823, Ho 2003 appeared somewhat similar to A. bariense by having 5 sepals and 3-4 pairs of opposite leaves, but the glabrous character of our specimen was intriguing, as that character is not seen in any of the previously reported Indo-Chinese Argostemma. Further examination of the morphology and study of some additional literature (Bremer 1989, Sridith 2007, suggested a close affinity with a Bornean species, A. apiculatum. However, examination of the type specimens and protologue showed no complete match with either A. apiculatum or any other earlier described taxa of Argostemma.…”

“…1). Some other glabrous species have also been reported from Thailand (Puff et al 2005, Sridith 2007) but they are morphologically very different from A. glabra.…”

“…and three species from the A. parviflorum group occur in the Malay Peninsula and on other Sunda islands (Bremer 1989). Sridith (2007) also noticed the Malesian Argostemma to possess fused anthers forming a cone-like structure that opens longitudinally, with scattered leaves along the stem, and a creeping/erect habit. All of these characters clearly match with A. glabra and hence, we think that the occurrence of A. glabra in the South Indochinese floristic province and its relatedness with A. apiculatum is not unlikely.…”

“…Argostemma is the largest genus in the Argostemmateae tribe of Rubiaceae, having about 220 described species distributed widely in tropical and subtropical Asia and two species in west tropical Africa (Verdcourt 1958, Robbrecht 1988, Bremer 1989, Mabberley 1997, Sridith 1999, Sridith & Puff 2000, Sridith 2007. They are usually terrestrial, often lithophytic, or occasionally epiphytic, perennial herbs.…”