Osmunda in Flora of China @ efloras.org

2. Osmunda Linnaeus, Sp. Pl. 2: 1063. 1753.

紫萁属 zi qi shu

Plenasium C. Presl.

Plants terrestrial, moderate-sized to large. Rhizome erect to shortly creeping, stout, woody, without scales. Fronds dimorphic or more commonly hemidimorphic with dimorphic pinnae; stipes arising as a crown at apex of rhizome, ± hairy when young, base of stipe swollen and with lateral flaplike stipules; lamina 1- or 2-pinnate, fertile portions reduced to a midrib with almost no lamina present; pinnae articulate to rachis. Sporangia large, naked, with a small patch annulus. 2n = 44.

About ten species, with some native hybrids; nearly worldwide in tropical and temperate regions, the greatest concentration of species in E and SE Asia; seven species including one putative hybrid species (one endemic) in China.

1 Fronds 2-pinnate; pinnae not articulate to rachis (O. subg. Osmunda) (2)

+ Fronds simple pinnate or pinnate-pinnatifid; pinnae articulate to rachis or not (3)

2 (1) Fronds dimorphic or only apical portion fertile; pinnules all ?equally sized. 6 O. japonica

+ Fronds hemidimorphic, lower pinnae fertile; apical pinnule of each pinna much enlarged. 7 O. mildei

3 (1) Fronds hemidimorphic; pinnae pinnate-pinnatifid, not articulate (O. subg. Claytosmunda Yatabe, Murakami & Iwatsuki). 1 O. claytoniana

+ Fronds simple pinnate; pinnae entire, undulate, serrate, or roughly dentate, articulate (O. subg. Plenasium (C. Presl) C. Presl) (4)

4 (3) Margin of pinnae roughly dentate. 2 O. banksiifolia

+ Margin of pinnae entire or serrate (5)

5 (4) Fertile pinnae basal. 5 O. vachellii

+ Fertile pinnae medial, or above middle (6)

6 (5) Margin of pinnae distinctly serrate; pinnae less than 1 cm wide. 3 O. angustifolia

+ Margin of pinnae entire, undulate, or minutely serrate; pinnae 1-2.5 cm wide. 4 O. javanica

Lower Taxa