Biochemical Systematics and Ecology, Vol. 14, No. 2, pp. 199-202, 1986. 0305-1978/86 $3.00+0.00 Printed in GreatBritain. PergamonPressLtd. Chemical Discontinuity in Laeliinae bentham* V. F. FERREIRA, J. P. PARENTE, M. C. F. R. PINTO, A. V. PINTO, B. PORTER, M. M. SILVA and J. L. MOUTINHO* N~cleo de Pesquisas de Produtos Naturais, Universidade, Federal do Rio de Janeiro, Centro de Ci~ncias da SaOde, Bloco H, 21941,Cidade Univeraitaria, Rio de Janeiro, R J, Brazil; *Herbarium Bradeanum, R J, Brazil Key Word Index--Encyclia; Anacheilium; Hormidium; Orchidaceae; druse-type pattern; dihydroflavonol; chemosystematics; phylogeny. Abstract--A new dihydroflavonol glycoside, anacheiloside, has been characterized in several species of the family Orchidaceae. The distribution of the flavonoid in druse-type patterns in flowers fixed in ethanol was used as a criterion to restablish the genus Anacheilium and correlate phylogeny among Encyclia, Anacheilium and Epidendrum. Introduction Most taxonomists now attribute more import- ance to biological concepts, such as genetic information, physiology, ecology and phyto- chemistry, considering them essential for the creation or delineation of new taxa, instead of relying strictly on morphological characteristics. Several groups of plants have been studied fol- lowing this approach, especially when it is diffi- cult to define them precisely because morpho- logical criteria were common among many species [1, 2]. These methods have the advantage in avoid- ing subjective opinions. For example, flavonoids [3] have been applied to help distinguish hybrid species. Ecological methods are also useful in studying species-species and species-habitat relationships [4] based on the presence of chem- ical components, allelochemicals, produced by plants (or animals). These have been used to study behaviour, classification and phylogeny. Recently Gottlieb et al. set up general principles to use allelochemicals to study evolution, sys- tematics and ecology in plants [5]. In the Orchidaceae, some work has been done utilizing chemical constituents in order to study their taxonomy, evolution and ecology. Tosello et a/. [6], using phenolic compounds from flowers, *This work is dedicated to the memory of the Brazilian orchidologist J. F. G. Pabst (deceased 1980). (Received 28 February 1985) made a phylogenetic study of the genera Catt- leya (Ldl.) and Laelia (Ldl.). Studies based on alkaloids, led to delimitation of sections in the genus Pragmipedium [7], affinities in the genus Dendrobium and correlations among the genera Malaxi, Lipares and Hammabya [8]. Williams has made use of flavonoids to clarify the relationship between orchids and other families of mono- cotyledons [9]. Chromatographical analysis has also been applied in studies of the floral fra- grance of C, ataseturn and Epidendrum, as well in other tropical and European genera [10-13]. Recently our group has published some papers which throw some light on the Epiden- drum/Encyclia controversy [14]. We found crystalline structures mainly in the flowers of the sub-genus Osmophytum (Ldl.) Dressier & Pollard. These crystals are very abundant in species of the drusa type and are distributed in all parts of the plant. The structures are not found in other plants of the same genus that did not show drusa type patterns. This difference was used to elevate the sub-genus Osrnophythum to genus rank, re-establishing the genus Anacheilium, created in 1842 by Hoffmanseg to describe Epi- dendrum cochleatum [15]. Our earlier studies described the chemical analysis of the crystals [16]. Here we present the structure of the com- pound involved, anacheiloside, based on its lzc NMR analysis as well as other spectroscopic data. We also present a list of plants which produce anacheiloside. 199