克氏粉背蕨 ke shi fen bei jue

Cheilanthes krameri Franchet & Savatier, Enum. Pl. Jap. 2: 212, 619-620. 1879; Aleuritopteris agetae Saiki; C. agetae (Saiki) C. M. Kuo.

Rhizomes erect, short; scales bicolorous, black with narrow brown margins, lanceolate. Fronds clustered. Stipe dark brown, lustrous, 10-25 cm × 1-1.5 mm, scaly from base nearly to midpoint; basalmost scales similar to rhizome scales, grading abruptly to concolorous, orangish brown, and broadly lanceolate. Lamina triangular or ovate-triangular, 6-20 × 4-12 cm, pinnate-bipinnatifid, papery or herbaceous when dry, abaxially with milky yellow or white farina, adaxially glabrous; pinnae 5-9 pairs, separated from each other by wingless rachis, basal pair triangular or triangular-lanceolate, 2-5 × 1-3 cm, bipinnatifid; basal basiscopic pinnules largest, pinnatifid; second and third pairs of pinnae with same shape as basal pair, but shorter and narrower; distal pinnae lanceolate. Veins obscure. Sori consisting of 5-7 sporangia, confluent at maturity. False indusia usually interrupted, broad, margins undulate to irregularly crenate, somewhat corrugate, usually farinose externally.

Rock crevices on slopes or cliffs; 1800-2700 m. Taiwan [Japan, Thailand].

The status of the Taiwanese endemic Aleuritopteris agetae remains unresolved. This taxon is said to differ from A. krameri s.s. in its milky yellow (vs. white) farina and stipe scales that are sometimes slightly bicolorous. Ralf Knapp (pers. comm.), the author of a recent authoritative guide to the pteridophytes of Taiwan, Ferns and Fern Allies of Taiwan (2011), has stated that where the two taxa grow together they are readily distinguishable in the field. However, based on examination of herbarium material collected in Taiwan, the present authors could not consistently discern two discrete morphological entities. Some of the specimens from mainland China also appear to have milky-colored farina. The situation requires further study.