45. Dryopteris purpurella Tagawa (Acta Phytotax.Geobot. 1: 307. 1932).—Fig. 47.

D. erythrosora (Eaton) Kuntze var. purpurescens H. Itô,

D. indusiata (Makino) Makino & Yamam. var. purpurescens (H. Itô) Kurata

Rhizome very short creeping to ascending. Stipe 20-30 cm long, purplish, the scales narrow triangular, cordate at base and then often narrowing gradually or abruptly to an attenuate gland tipped apex, pale margined or not, brown and black or all greenish, to 7.5 mm long; blade ca. 30-45 cm long, 20-35 cm wide, triangular to broad-ovate, mostly 2-pinnate, abruptly narrowing to a pointed apex, rachis purplish; pinnae lanceolate to narrow triangular, pinnatisect to pinnate, acute to acuminate, attached at right angles or nearly so to the rachis, often somewhat distant, costa with tannish bullate scales; pinnules oblong to elongate elliptic, the teeth somewhat narrow triangular-mucronate; the pinnule next to the rachis on the lowest pinnae only slightly reduced, sometimes pinnatifid. Sori typically submarginal; indusia round-reniform, whitish-tan and faintly pink at center, slightly convex.

Dryopteris purpurella has been reported as a having both triploid and tetraploid races, both apogamous fern from Japan (Hirabayashi, 1974). It is native to Japan. It is an attractive, medium-sized fern that grows with restraint and has an interesting color in the new foliage. Only a few plants exist in U.S. and have recently been introduced from Yakushima, Japan, by the senior author. The purplish stipe and rachis, the 2-pinnate flatter fronds with ca. 6 pinnate pinnae well spaced apart, the proximal pinnae at or nearly at a right angle to the rachis, and the submarginal sori help to discriminate D. purpurella.

According to several Japanese botanists, the U.S. cultivated material sold as D. purpurella is not that species, though the stipe and rachis may initially be pinkish. In the U.S. material the larger fronds are basally 2 pinnate-pinnatifid to almost 3 pinnate, with ca. 10 pinnae (contrast with description above) that are broader and closer together, and the basiscopic pinnule next to the rachis is shorter than in D. purpurella. Young fronds of such plants do look somewhat like D. purpurella, but older fronds are too foliaceous and the pinnae are markedly crowded. They have been identified as D. erythrosora, the variability of which is discussed above under that that species' treatment.

Dryopteris purpurella is hardy to a January average of above 40°F, is more or less evergreen, and has new growth that is purplish pink to bronze.