NAT. NAT. HIST. BULL. SIAM Soc. 43: 337-365 ， 1995 ECOLOGICAL ，MORPHOLOGICAL AND TAXONOMIC STUDIES ON THAILAND'S FIFTH SPECIES OF RAFFLESIACEAE: RHIZANTHES ZIPPELll (BLUME) SPACH Hans Banziger* ABSTRACT A1 1 22 c1 usters of Rhizanthes zippelii studied in τbai1and (where it is confirmed for the first first time) and in W M a1 aysia pぽ asitized exc1usively Tetrastigma pedunculare (W all. 巴x Laws.) P1anch. P1anch. (Vitaceae) a1 though other Tetrastigma spp. were a1 so present ，some reported as hosts elsewhere.τbe mo 中 hology and eco1ogy of the host liana 釘 ed 巴tai1 巴d. Most1y its only connection connection with the ground was by aerial roots and R. z伊'pelii gener a1 1y grew on 血ese ne 紅 ground ground leve l. Morphologic a1 evidence indicates 出at R. lowi (B 巴cc ぽ i) H 紅 ms ，described from buds ，is best synonymized with R. zippelii ， a rather variable species. From extrapo1ation of growth growth measurements ， buds would need some 200 days to reach a circumferenc 巴 of 3.7 -4 .1 cm (when 出ey break through the host b訂 k) from a swelling of 0 .5 cm diameter ， and another 200 200 to maturity when 14.7-20.5 cm in circumference. Fl owers start to open 釘 'ound midnight and and are fully open arQund noon the following day (a1 though insects first visit during ear1y moming) and remain fresh for 2-3 days. Th e mush-like pollen is gener a1 1y dep1eted in 白 e first day day but pollinating f1i es (C a1 liphoridae ，Diptera) continue to visit for many days. 百le pollen mush c1 0ts and hardens once smeared by f1i es onto their bac k. Experiments show 白紙 h釘 d- ened ened pollen mush retains substanti a1 gen 凶nability for m 釦 y days 組 d 白紙c1 0tting is readily reversed reversed when swept over 出 e fluid-soaked stigma. Nectar is exuded ne 紅 the tip of 白e perigones. perigones. A ‘sωffy room' odour comes 仕om 血e perigonelcolumn 飢 da weaker excrementl cheese-like cheese-like smell from the caudate appendages. R. z伊>p elii is a sapromyophilous flower which acts acts main1y by brood ・site deception. INTRODUCTION An encounter in a steamy rain forest with a flowering Rhizanthes z伊'pelii makes 姐 intruder intruder wonder.τ 'h e look of 出e flower is more 北 in to a tentacled animal-a starfish or medusa-than to a member of 出e plant kingdom. But at 出es 創 ne time the reddish globe with crater ，embedded 泊 a tangle of rufous hairs ，reminds one of the blood-shot orifice of a furry mammal. Th is pe 甲lexing aspect is p制 of 組 intricate set of lures: visual ，tactile ， olfactory olfactory and gustatory ， as treated in a second study on 血e plant' s pollination syndrome (BANZIGER ， 1996). The present state of know1edge of Rhizanthes Dumortier has been aptly reviewed by MEUER & VELDKAMP (1988) ，with data on its nomen c1 a加ra1 history ，mo 中 hology and anatomy (e.g. SOLMS-LAUBACH ，1876 ，1898; HE 町 RICHER ，1905; CAMME 乱 OHER ，1920) ， seeds (SOLMS-LAUBACH ，1874 ，1898) ， pollen morphology (TA Kl汀 AJAN ET AL. ，1985) ， cytology (町凡， 1933) ，geographic dis 凶 bution 阻 d， as far as the sometimes deteriorated and *Department *Department of Entomology ，Faculty of Agriculture ， Chiang Mai University ， Chiang Mai ，Thailand ， 50200 337 338 HANS BANZIGER incomplete incomplete museum material allowed ，detailed taxonomic description. Pr eviously known ，among else ， mainly under Brugmansia Blume ， at present two species 紅 e 閃 cog 凶zed ， viz. R. zippelii (Blume) Spach and R. lowi (Becc 訂 i) Harms ， di 姐 ibuted in Suma 回， W Malaysia ，Bomeo and ， for R. z伊llelii ， also Java (MEUER & VELDKAMP ，1988). 百le present study proves 血e presence of R. z伊llelii in Thailand for the the first time ，a finding which is not entirely unexpected as 由e species is included in a list of 百凶plant n創 nes(SMIτ 1N AND ， 1980). However ， Dr. T. Smitinand informed me 白紙 he had never seen 出e pl 叩 t ，despite his life-long field experience; 白紙 the record originated from his predecessor; and 出at 白ere is no herbarium material from Thailand (if any had ever ever been collected). Furthermore ， the record remains dubious also because one of the local local names listed was 出e same as that for Rafflesia kerrii M 吋民 b，ua phud (前朋) with which it might have been confused ， while another is bua khrang (u 'lf'l f.:J). The present study increases increases to four the numb 巴r of genera of Rafflesiaceae present in Thailand ， the other three being being Sapria Gri 白血 (wi 血 two included species) ，Mitrastemma Makino and Rafflesia R. Brown (wi 白 one 百聞 species each) (HOSSEUS ， 1907; HANSEN ，1972a ， b; MEUER ， 1984; BANZIGER ， 1991). Less Less is known about the biology of Rhizanth 自由an the still poorly understood Rafflesia Rafflesia and Sapria while Mitrastemma has been comprehensively researched by WATANABE (1 936 ， 1937). The bud phenology of Rafflesia and Sapria is known 旬 some extent extent (MEIJER ， 1984; ELLIOπ ，1990 ，1992) ， as is 白 e pollination biology of Rafflesia (BEAMAN ET 札.， 1988; B 加 ZIGER ，1991) 出ough it is poorly known in Mitrastemma 叩 d unknown in Sapria. Seed dispersal and host infection are st i1l a matter of sp 田 ulation for all all of them. For Rhizanthes ，among the least known of the nine genera of Rafflesiaceae ， even mo 中hological aspects and taxonomy 紅 'e far from elucidated. Thi s is perhaps due to its its variability ， complicated by the peculi 紅 presence of bisexual as well as male and female flowers ， as a1r eady noted by SOLMS-LAUBACH (1 876) and HE 別問CHER (1 905). Otherreasons are are its secretive mode of life and a disconcerting ， to some people even repulsive aspect ， with with hairs which look like they could sting 姐 d appendages which ， during the ope 凶ng phase phase of the flower ，resemble 出e trap spikes of a carnivorous plan t. This did not endear it it to local people or the occasional collector. The most detailed biological notes so far have been on the longevity of 2 or 3 flowers and 白eir odour ，made on four occasions by F. Bartel (HE 問問C田 R， 1905). Several authors have have commented on the smell produced by the flower. Visiting insects were identified as carrion carrion flies ，仕 uit flies ，gnats ，ants ，etc. DELP 町 o (1868) attempted a 缶百 t interpretation of of the pollination mechanism. STUDY SITES AND HABITATS 百】 e study 紅 eas consisted of 白ree sites in evergreen rain fores t. The most northerly was in Su 拙註in Di s凶ct ， Narathiwat Province ， South Th ailand. The other two were between Gopeng and Chenderiang ， South Perak ，Peninsular Malaysia ， the general 紅 'ea mentioned by MOLESWOR' 百 I ALLEN (1 968). Site Site (a) 也 S Th ail 叩 d was along a 5-15 m wide s悦組n in a2 0- 50 m broad gully meandering meandering southwards to westwards ， at 26 0- 340 m msl (mean sea level). 13 clusters of STUDIES ON RHlZANTHES ZIPPEUI (RAFFLESIACEAE) 339 R. R. zippelii-four only with dead buds or desiccated flowers but possibly with live thalli inside inside the host-were dis 位ibuted over a distance of about 1 km. The clusters were less 出an 3 metres from the stream though two were about 10 m from it.百 le forest (Fig. 1) was variably shady with estimated total daily sunflecks reaching the clusters from a minimum of of 112 to a maximum of 2 h. Site Site (b) (shown to me by Mr. M. Wong) was a north-flowing ， 15 m broad ， shallow 抑 'eam bed s位ewn with stones ，gravel and various plants at 330 m ms l. The wa 町 flowed between between and below them; after heavy showers 白ey would be briefly be inundated. Much of of the 訂 ea was covered by a species of Ar aceae. Despite careful checking of 血e surroundings surroundings only two clusters of R. zippelii were found ，30 m ap 紅 t， both in the stre 創 n bed ，where the vegetation was most open. Thus ， while the soil was perpetually wet ， the habitat habitat received more light 白血血e average understorey vegetation ， with sunflecks reaching the the flowers for about 2-3 h daily. Site Site (c) was in a sep 紅 ate valley about 2 km from site (b) and consisted of 7 clusters (2 (2 shown to me by an Orang Asli ，5 found by mysel f) s住'ewn over about 112 km ， in a n紅 TOW gully along a stream ，35 0-4 50 m msl ， exposed SE to SW.τ 'h e habitat was essentially the the same as that of (b) but more shaded. Sunflecks nevertheless reached the clusters for up to 112 h daily. One cluster was on rocks in the stream bed ， the others on adjacent gravelly gravelly b創 lks a few metres from the stream. τ'h e 訂 ea of study in S Th ailand is under the influence of the east coast weather regime -heaviest -heaviest rain in November and December ， followed by a relatively dry period in March- May with low rainfal l. During 30 March to 17 April 1995 only 4 late aftemoon showers were experienced. Mid-day temperaωres were 26- 30 "C and relative humidity (RH) was 65-90 % (quite high considering that it was the ‘dry' season ， obviously the result of humid ， nearly constant ， though slow wind drifts down along the stream). 百le minimum night night temperature was 21 "C at 100% RH.