Kitichate Sridith

The pollination ecology of durian ( Durio zibethinus , Bombacaceae) in southern Thailand

The floral biology and pollination ecology of durian, Durio zibethinus , were determined in eight semi-wild trees in mixed-fruit orchards in southern Thailand during April-May 2003 and 2005. Flowers open fully at 16h00–16h30 and most androecia drop around 01h00. Anthers dehisce at 19h30–20h00 when the stigmata are already receptive. In a series of pollination experiments, fruit was set in all treatments within 10 d. The greatest pollination success occurred after hand-crossed (76.6%), open (54.4%) and emasculation pollination (53.3%). Consistently, hand-crossed (12.2%), emasculation (8.7%) and open pollination (5.1%) yielded a substantial fruit set 2 mo after the pollination experiments. Very low pollination success in facilitated autogamy suggests that most durian trees are highly self incompatible. No mature fruit was found after insect pollination and automatic autogamy. Fruit bats, especially Eonycteris spelaea , are the major pollinators of this durian although the giant honey bee ( Apis dorsata ) was the most frequent visitor to the flowers. Bats visited durian flowers at the rate of 26.1 (SD = 20.7) visits per inflorescence per night. Since this semi-wild durian depends on fruit bats as its pollinator, protecting fruit bat populations and their roosts is vital for the production of the durian fruit crop.

The pollination ecology of two species of Parkia (Mimosaceae) in southern Thailand

Although the floral traits of Parkia conform to the bat-pollination syndrome, many visitors other than bats have been observed at their flowers. Some chiropterophilous plants are also pollinated by other animals; the syndrome is therefore best regarded as a hypothesis for which field observations and pollination experiments are required. The present study aimed, for the first time, to determine the breeding system of the economically important canopy trees, Parkia speciosa and P. timoriana , and to identify their pollinators. Pollination experiments carried out in Trang and Songkhla Provinces, in 28 trees of P. speciosa and four P. timoriana indicated that they are self incompatible. Open pollination resulted in the highest fruit set (average 60–67% of inflorescences per tree) although this was not significantly different from hand-crossed pollination (48–60%). Insect pollination resulted in fruit set in only 12% of P. speciosa inflorescences. Fruit bats, mainly Eonycteris spelaea , visit flowering plants continuously from dusk till after midnight. Nocturnal and diurnal insects (moths and stingless bees respectively) visit capitula, mostly at the nectar zone. Nectarivorous bats are the most effective pollinator for P. speciosa and P. timoriana . The fact that populations of E. spelaea appear to be declining throughout their distribution is therefore a matter of increasing concern.

Character intercorrelation and the potential role of phenotypic plasticity in orchids: a case study of the epiphyte Liparis resupinata

Character intercorrelation was studied in a natural population of the epiphytic orchid Liparis resupinata in northern Thailand, and patterns of morphological variation in relation to the local growth environment of individual plants were mapped. Massive occurrence of character intercorrelation was detected, but clone size only influenced few characters of individual flowering shoots. Variation in vegetative and floral organs was largely independent, but two cases differed from the general pattern: (1) the only character not defined by size (distance between apices of lateral sepals) exhibited largely independent variation; (2) ovary length was positively correlated with nearly all other characters. Major groups of vegetative and floral characters were found to covary with different combinations of ecological parameters. Although our study does not document the existence of phenotypic plasticity in L. resupinata, the overall patterns observed would be congruent with a scenario involving phenotypic plasticity. No positive correlation between variability and apparent morphological susceptibility to environmental influence was found; but floral characters were generally less variable and covaried with more ecological parameters than vegetative characters. Based on our observations, we make a few methodological recommendations for morphometric studies of species complexes.

The Genus Plagiochasma (Aytoniaceae, Marchantiopsida) in Thailand

Abstract The genus Plagiochasma Lehm, et Lindenb. in Thailand is reviewed, based on herbarium specimens and especially on recently collections. The genus is reported for the first time from Thailand. Two species are recognized, namely P. appendiculatum Lehm, et Lindenb. and P. cordatum Lehm, et Lindenb. Descriptions, illustrations, and a key to species are provided.

A NEW SPECIES OF BEGONIA (BEGONIACEAE) FROM PENINSULAR THAILAND

A new species from Thailand, Begonia bella Phutthai (Begoniaceae), is described and illustrated. It belongs in Begonia sect. Parvibegonia and is a narrow endemic in Phangnga province. Its IUCN category is considered to be ‘Vulnerable’.

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

The 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 during November 2001 – December 2006.

Establishing species distributions in large tropicalplant genera: insights from twelve new Thai records of Oberonia (Orchidaceae)

Establishing species distributions is particularly challenging in large tropical genera of inconspicuous plants. One such genus is Oberonia (Orchidaceae) which we are currently revising for Thailand. When encountering material of a putatively new species, great care has been taken to make a wide geographic search for matching extra-Thai taxa. Against this background, we here record 12 species as new for Thailand: O. dissitiflora, O. evrardii, O. gracilis, O. insectifera, O. lotsyana, O. microphylla, O. orbicularis, O. semifimbriata, O. singalangensis, O. stenophylla, O. suborbicularis, O. wenzelii. Seven records are based (at least in part) on older collections, suggesting that many gaps in currently known species distributions can be filled through revision of existing collections alone. Our wide geographic search for taxonomic matches had three important implications: 1) we succeeded in identifying five species that had not previously been recognized for Thailand or neighbouring regions; 2) we realized that circumscription of three species should be widened, with implications for their known distributions; 3) comparison of numerous collections enabled us to report additionally six new records (O. evrardii for Myanmar; O. insectifera for Papua New Guinea; O. semifimbriata for Borneo; O. wenzelii for India, Myanmar and Java). Eventually, we draw attention to new online tools and resources that facilitate improvements of taxonomic and geographic knowledge in large tropical genera.

How does sampling strategy influence detection of morphological variation in orchids? A case-study of the epiphyte Oberonia hosseusii

Effects of sampling strategy on detection of morphological variation were studied in the epiphytic orchid Oberonia hosseusii in Thailand. We compared the different effects of local versus regional sampling on the one hand and the size of local samples on the other. A local data set was collected by sampling a natural population on Doi Inthanon, during which process a preservation experiment was made. A regional data set was established by measurement of 18 preserved specimens from 12 different localities. Based on the preservation experiment, data from the regional sampling were calibrated (whenever needed) to make the two data sets more directly comparable. Heat drying and spirit preservation significantly influenced measurements for two mutually exclusive sets of characters. Increasing the local sample size from 18 to 52 individuals had no statistically significant effect on the mean value of any character. In contrast, local versus regional sampling significantly influenced the mean value of every character, virtually irrespective of local sample size. In the regional data set only, a difference was found in overall variability in vegetative versus floral characters. Three cluster analyses with equal representation of individuals from the local and regional samples were performed using different clustering techniques. Only in the analysis using neighbour-joining did pure “local clusters” prove to be significantly larger than pure “regional clusters”, suggesting that this clustering technique is particularly sensitive to effects from sampling strategy.

Argostemma phyllocharis, a new species of Rubiaceae from Northern Thailand

SummaryArgostemma phyllocharis Sridith, a new species from Ban Pha Sue, Mae Hong Son province, Northern Thailand, is described and illustrated, and a chromosome number count is given.

Exploring the patterns of alpine vegetation of Eastern Bhutan: a case study from the Merak Himalaya

A survey was conducted from March to September 2012 along the altitudinal gradient of the Jomokungkhar trail in the Merak Himalaya of Sakteng Wildlife Sanctuary to study the floristic compositions and the patterns of alpine vegetation of Eastern Bhutan. The vegetation of the sampled plots is classified into five types of communities based on the hierarchical cluster analysis at similarity index 63% viz., (1) Riverine Community; (2) Abies–Rhododendron Woodland Community; (3) Juniperus Scrub Community; (4) Rhododendron Krummholz and (5) Alpine Meadow, based on the floristic compositions. In addition, it was noticed that the fragile alpine environment of the Merak Himalaya has high plant diversity and important plants that are susceptible to the anthropogenic pressures.