Abstract

Taxonomic review of the genus Calocedrus in Vietnam accompanied with modern available data on distribution, ecology and habitat conditions of its two aboriginal species is presented. Detailed illustrated description of recently discovered species C. rupestris endemic to rocky limestone mountains of northern Vietnam is provided. This rare species differs from wide-spread C. macrolepis in obtuse to broadly-obtuse leaf apex; small, subsessile, 4-scaled, broadly-ovate seed cones 4-5(6) x 2.5-3(3.5) mm with very short stalk 0.5-1(1.5) mm long, having 6-8(12) obtuse scales, and fertile seed scales with incurved rounded apex having rough, more or less flat surface without any mucro. Trees of C. rupestris were found as a co-dominant in relictual coniferous forests on rocky hills and ridges composed of highly eroded limestone. Relictual primary, highly endangered woods with this rare tree, as well as their floristic complex represent a unique plant diversity center of global significance. Urgent and effective protection of these areas should be of highest priority for nature conservation activity.

中文摘要

本文主要是訂正越南產肖楠屬（Calocedrus）植物，並報導一產自越南北部石灰岩山區的特有新種岩生肖楠（Calocedrus rupestris）及廣佈種大鱗肖楠（C. macrolepis）的分佈、生態及生育地等資訊。岩生肖楠與大鱗肖楠最大差異在於前者鱗葉先端鈍狀或寬鈍狀；四鱗片排列的小型毬果呈寬卵形約4-5(6) x 2.5-3(3.5) mm2，共約6-8(12) 枚鈍狀鱗片，具短柄 (約0.5-1.5 mm)；肥厚的種鱗具彎曲圓形的先端但絕不呈微凸狀，表面平坦但粗糙。岩生肖楠植株主要出現在由腐蝕性強的石灰岩組成山脊或石山，伴隨著殘存的松林而岩生肖楠幾乎也是該處優勢種。在此瀕危森林及此稀有物種所組成的複雜區系卻也是代表這片森林具有獨特地植物分化中心意義。有鑑於此，緊急與有效的保育此自然生育地將是刻不容緩的當前之務。

Keyword: Cupressaceae, Taxonomy, Calocedrus macrolepis, Calocedrus rupestris, Vietnam. 柏科、分類學、岩生肖楠、大鱗肖楠、越南。