Costus afer - C. lucanusianus Complex(オオホザキアヤメ科)の解剖と分類 Anatomy and Systematics in the Costus afer - C. lucanusianus Complex (Costaceae)

これまで分類が混乱していたオオホザキアヤメ属の3分類群の関係を明らかにするために, 葉身, 根茎, 根の比較解剖をおこなった。解剖学的な違いによって, これまで同種としてきた考えに反して, Costus aferとC. lucanusianusは別種とすることの妥当性が示された。しかし, これらの種の交雑個体は, 解剖学的な差異はあるものの, 別種とする必要はない。この研究によれば, 葉肉の厚さはCostus aferでは3〜4細胞層で, C. lucanusuanusでは4〜5細胞層で, 推定交雑個体では2〜3細胞層であった。根の維管束系はC. aferでは6原型, C. lucasianusでは9原型, 交雑個体では多原型で, この形質は種を区別する重要な特徴を示す。

The anatomy of lamina, rhizome and root of three taxa of Costus was investigated with a view of establishing interrelationships among the previously confused species of the genus. Differences in features of the vegetative anatomy suggest that a separate specific status for C. afer and C. lucanusianus is justified as opposed to the conspecific treatment given to them by previous researchers. A hybrid collection of these Costus species does not merit a separate specific status, although it possessed distinct anatomical features. The systematic importance of this investigation is clear since a 3-4 layered spongy mesophyll of C. afer is different from a 4-5 layered spongy mesophyll of C. lucanusian~ and the 2-3 layers of the putative hybrid. Similarly the hexarch, nonarch and polyarch vascular bundle of the root of C. afer, C. lucanusianus and the Costus hybrid respectively, are all distinguishable attributes of these taxa that are important in systematics.