Cheilanthes kuhnii var. brandtii and the Composition of Its Farina

Abstract

Cheilanthes kuhnii Milde var. brandtii (Fr. & Sav.) Tagawa is a fern endemic to central Honshu in Japan. This fern is morphologically characterized as follows. The fragile stipes are 8-20 cm long, castaneous, and bear broadly lanceolate, pale brown scales on the lower parts. The laminae are narrowly ovate, tripinnatifid, 15-30 cm long, and 6-13 cm wide. They are summer-green, thinly herbaceous, and more or less farinose beneath. The indusia are continuous in fully soriferous leaves, but sometimes are interrupted in less soriferous ones. According to Ching (1941), this fern belongs toAleuritopteris sect. Dalhousiae, characterized by not or thinly farinose laminae and relatively thin texture. He regarded it as being identical with C. kuhnii Milde var. kuhnii of Korea, Amur, Manchuria, and North China. But typical C. kuhnii of the mainland of Asia has lanceolate and rather deeply dissected laminae. The Japanese plants seem to be more appropriately treated as a variety of C. kuhnii. Cheilanthes kuhnii var. brandtii is usually not rare in the habitats where it grows, but its geographical range is limited to the limestone areas of central Honshu. It is usually found in rather open, dry, and more or less disturbed places, such as on roadside rocks or stone walls near villages, but rarely is found on moist and shaded rocks deep in the mountains. The density of the white farina on the lower surface of the lamina is strongly influenced by the habitat. The plants in open and dry places bear a considerable amount of farina, whereas those in moist and shaded places are hardly farinose. Makino (1917) described var. efarinosa having non-farinose laminae, but it seems to be only an extreme form not worthy of varietal distinction.