Taxonomy and Distribution of Circaea (Onagraceae) in the USSR

Abstract

In the USSR, five species of Circaea are recognized: C. alpina L., C. caulescens (Kom.) Hara, C. lutetiana L., C. cordata Royle, and C. mollis Sieb. & Zucc. Also, the sterile hybrid C. x intermedia Ehrh. is known from several regions. Distribution areas of all these taxa are presented on maps based on herbarium materials studied by the author. Among these materials, no specimen of C. erubescens Franch. & Savat. has been detected, though this species had been reported from southern Sakhalin previously. Circaea caucasica A. Skvortsov, described by the author earlier, is now regarded to be a disjunct fraction of C. caulescens. The genus Circaea has few species, and they are sharply delimited taxonomically and very distinct and uniform morphologically and ecologically. All Circaea species are tender, broad-leaved, shade- and moisture-loving herbs. The overall area of the genus closely coincides with the area of temperate mesophilic (broadleaved, mixed, and dark-coniferous) forests of the northern hemisphere. Hence, from the study of taxonomic interrelations within the genus Circaea, one could expect to get interesting suggestions regarding the history of mesophilic temperate forest in general. I have been interested in Circaea for many years, and have previously published a few short notes on the subject (Skvortsov 1970, 1971, 1977). The present paper provides a general taxonomic and geographical review of this genus within the USSR. I have studied Circaea both in the field and in herbaria. Field observations have been made chiefly in the following regions of the USSR: central part of the European territory (provinces of Moscow, Kaluga, Smolensk); Ukrainian Carpathians; Crimea; central part of the Great Caucasus; Altai Mountains; southern part of the Soviet Far East (Primorski Province). Outside the USSR, I have had the opportunity to observe and to collect Circaea species in Sweden, in the Indian Himalayas, and in the southern Appalachians. Herbarium materials of the following institutions have been studied in full: Komarov Botanical Institute in Leningrad (LE); Botanical Institutes in Kiev (KW), Minsk (MSK), Erevan (ERE), and Wilnius; Biological Institutes in Riga (LATV), Syktyvkar (SYKO), and Vladivostok (VLA); Institute of Zoology and Botany in Tartu (TAA), Institute of Ecology in Sverdlovsk (SVER), Siberian Institute of Plant Physiology and Biochemistry in Irkutsk (IRK), Main Botanic Garden in Moscow (MHA), Central Siberian Botanic Garden in Novosibirsk (NS); Universities of Moscow (MW), Leningrad (LECB), Tartu (TU), Riga (RIG), Wilnius (WI), and Vladivostok. In part, materials also have been studied from the Universities of Uppsala (UPS) and Lund (LD).