The status, ecology and conservation of Sapria himalayana Griff. (Rafflesiaceae) in Thailand

ABSTRACT:  

Sapria himalayana (Griffith, 1845) (Rafflesiaceae) is a parasitic plant with spectacular red flowers about 20 cm across which grows in the roots of lianas. The objectives of the study reported here were to determine the current status and distribution of S. himalayana in Thailand and to investigate the plant's reproductive ecology in order to determine how best to conserve the species. I could confirm the continued survival of the species at one site in Chiang Mai Province and another in Mae Hong Sorn and received recent reports of the species from Tak and Kanchanaburi. Host lianas were Tetrastigma obovatum (Laws.) Gagnep. (Vitaceae), T. laoticum Gagnep. and T. cruciatum Craib & Gagnep. (Vitaceae) in evergreen forest at 1000 - 1300 m above sea level. Unisexual flowers, with a sex ratio of 2.17 males per female, opened after a developmental period of 99-122 days (99% confidence limits) in September-April with a peak (73.4 %) in November-January. Flies may carry out pollination, whilst seed dispersal may be effected by small rodents. Of 545 buds examined, 40 % died before reaching maturity, mostly due to abortion. Mortality rates of males and females were the same. According to IUCN Red Data Book criteria, S. himalayana is endangered with extinction. Sites where the plant grows should be better protected, collection or trade of the plant should be forbidden by law and attempts should be made to pollinate the flowers by hand and transfer seed to new hosts in natural habitat. Raising the species in botanical gardens will not be successful due to the species' complicated ecology.