Morphological, ecological, and cytological studies on cultivated and wild butterburs, Petasites japonicus MAXIM

Abstract

Butterbur, Petasites japonicus MAXIM., called “Fuki” in Japanese, is a deciduous perennial herb belonging to Compositae, and is growing wild almost all over Japan. Gigantic butterbur, subsp. giganteus KITAM., commonly called “Akitabuki”, is restricted in its distribution to the northern Japan such as Hokkaido and Tohoku districts. Butterbur is cultivated as a leaf-vegetable or for processing in Osaka, Aichi, Akita and other prefectures, and its cultivation has a long history. Stocks of cultivated and wild butterburs have been collected from various localities of Japan and cultivated for several years at the experimental farm of the University of Osaka Prefecture in Sakai City. Morphological, ecological and cytological studies have been carried out in order to elucidate the origin of cultivated varieties in relation to wild types and to provide basic information for future works of butterbur breeding. The present paper deals with the morphological and ecological studies on the cultivated and wild butterburs and on the geographical variations of those characters in wild types in relation to the latitube and altitude of their habitats. 1. The two cultivated varieties, “Aichiwasebuki” and “Mizubuki”, are distinguished in their larger size of leaf blade, longer petiole, more vigorous growth habit, and earlier sprouting of leaves in spring than those of wild ones (Fig. 2). 2. Wild butterburs showed a wide range of variations in their morphological and ecological characters when grown under the same conditions, but any definite geographical differentiation of those characters could not be found. Some stocks of wild butterbur had characters as excellent as those of the cultivated ones (Figs. 1 and 3). 3. The habit of “Akitabuki” to grow gigantic was not manifested in the experimental farm where it was warmer and drier than in its habitat (Figs. 1 and 2). 4. It was found that the seeds of wild butterburs did not undergo dormancy. 5. It was assumed that the cultivated varieties might be derived from certain wild stocks having desirable characters as vegetable crop, because of the fact that the useful characters can be easily and frequently found in wild ones.