Arundina

Abstract: Twenty-one Rhizoctonia-like fungal strains were isolated from the roots of four terrestrial orchid species from various locations in Hong Kong. The cultural morphology, nuclear number of the hyphal cell, pore ultrastructure, and RAPD and CAPS analyses of rDNA fragments revealed that most of these isolates were associated with the genera Ceratorhiza and Epulorhiza. RAPD analysis showed the presence of genetic diversity between the isolates from different hosts and locations. The compatibility between a selection of these Ceratorhiza and Epulorhiza isolates and 14 orchid species was determined using a symbiotic germination method. The germination and development of three orchid species, Arundina chinensis, Spathoglottis pubescens, and Spiranthes hongkongensis, were strongly stimulated by the Epulorhiza isolates. Habenaria dentata was found to form symbionts successfully with a Ceratorhiza isolate.

Abstract: From the orchid, Arundina bambusifolia, were isolated two new stilbenoids, arundin and arundinin, besides p-hydroxybenzaldehyde, batatasin III, lusianthridin, flavanthrin, flavidin and the polyphenyl propanoid-malonate-derived compound 3,3′-dihydroxy-2,6-bis-(p-hydroxybenzyl)-5-methoxybibenzyl of previously known structures. Arundin and arundinin were shown to be 3-hydroxy-2,6-bis-(p-hydroxybenzyl)-5-methoxybibenzyl and 3,3′-dihydroxy-4-(p-hydroxybenzyl)-5-methoxybibenzyl, respectively, mainly from spectral evidence.

Abstract: NewPhytol. (1977) 78, 365-372. DIURNAL STOMATAL AND ACIDITY RHYTHMS IN ORCHID LEAVES BY C. J. GOH, P. N. AV ADHANI, C. S. LOH, C. HANEGRAAF* and J. ARDITII* Department of Botany, University of Singapore, Singapore, JO (Received 28 August 19 76) SUMMARY The stomata of Arachnis cv. Maggie Oei, Aranda cv. Deborah, Arundina graminifolia, Bromheadia finlaysoniana, Cattle ya bowringiana X C. f orbesii and Spathoglottis plicata (Orchidaceae) occur only on the lower epidermis of the leaves and are located within hyper- stomatic chambers formed by cuticular ledges extending from the guard cells. Arachnis, Aranda and Cattleya have thick leaves which exhibit Crassulacean acid metabolism, and their stomata open when acidity levels are lowest, or shortly thereafter. Aranda and Arachnis require higher light intensities for sufficient deacidification to permit stomatal opening than Cattleya. Stomata of the thin-leaved Arundina, Bromheadia and Spathoglottis open during the day. The stomatal rhythms, morphology and distribution, as well as the pathways of carbon fixation and light requirements for deacidification, reflect the natural habitat of each species or the parents of the three hybrids. INTRODTJCTION Diurnal fluctuations of acidity in orchids were first reported nearly 100 years ago (Warburg, 1886). Since then there have been several reports of increased acidity as well as C0 2 uptake and stomata! opening in the dark in a number of species (Bendrat, 1929; Borriss, 1967; Coutinho, 1964, 1965, 1969, 1970; Coutinho and Schrage, 1970; Khan, 1964; Kristen , 1965; McWilliams, 1970; Milburn, Pearson and Ndegwe, 1968, Nuernbergk, 1963). More recently, dark 14C0 2 uptake and fixation have been shown to occur in the leaves of Arachnis cv. Maggie Oei (Arachnis hookeri'ana X A . flos-aeris), A. hookeriana var. luteola, A. flos-aeris, Aeridachnis cv. Bogor (Arachnis hookeriana var. luteola, X Aerides odoratum), Aerides odoratum and Cattleya (Borriss, 1967;Knauft and Arditti, 1969; Lee, 1970). Other findings suggest that certain orchids may fix carbon via the C4-dicarboxylic acid pathway (C4-PS). These include mature leaves of Arachnis cv. Maggie Oei (Lee, 1970) and possibly Cattleya (Knauft and Arditti, 1969). However, this is not the case with Arundina graminifolia, Bromheadia finlaysoniana, Coelogyne mayeriana, C. rochussenii, Cymbidium sinensis, C. cv. Cym-doris, and Eulophia keithii (Avadhani and Goh, 1974; Hatch, Slack and Johnson, 1967; Wong and Hew , 1973). Since epiphytic and saxicolic orchids exist under essentially xerophytic conditions, crassulacean acid metabolism (CAM) would hold the same advantages for them as for other xerophytes. Further, because some tropical orchids grow under high light intensities and temperatures, C4-PS would have the same value for them as for grasses under similar con- ditions. An obvious question arising from consideration of carbon fixation pathways in *Present address: Department of Developmental and Cell Biology, University of California, Irvine, CA 92717, U.S.A.

Abstract: A chemical investigation of the Orchidaceae Arundina gramnifolia has led to the isolation of a novel stilbenoid, named arundinan (1). The structure of 1 has been elucidated as 2-(p-hydroxybenzyl)-3-hydroxy-5-methoxybibenzyl on the basis of physical and chemical evidence and spectral analysis.

Abstract: A novel benzyldihydrophenanthrene named arundinaol (1) has been isolated from the rhizoma of Arundina graminifolia. The structure of 1 has been elucidated as 7-hydroxy-1-(p-hydroxybenzyl)-2,4-dimethoxy-9,10-dihydrophenanthrene on the basis of physical and chemical evidence and spectral analysis.