FERNS OF THE MALAY-ASIATIC REGION. 15 



OSMUNDA Linnaeus. 



Sporangia entirely covering very reduced segments which may make 

 up certain pinnae, or whole fronds, the fertile pinna; more compound 

 than the sterile; fronds pinnate or bipinnate, pinna; and pinnules ar- 

 ticulate to rachises. Ten species, one in Brazil, beside the following. 

 The three species of the eastern United States all reappear in eastern 

 Asia, but ai'e wanting in the western United States. 



Sterile fronds bipinnate (Eu-Osmu.nda) . 

 Pinnules not acute at base. 



Pinnules oblong or lanceolate, not adnate 1. 0. regalis 



Pinnules almost round, mostly adnate 2. 0. mildei 



Pinnules acute at base 3. 0. lancea 



Sterile fronds deeply bipinnatifid (Osmundastrum) . 



Fertile and sterile fronds distinct 4. 0. cinnamomca 



Fertile and sterile pinnules on same frond 5. 0. claytoniana 



Sterile pinnae not deeply pinnatifid (Plenasium). 



Pinna; narrowly linear G. 0. bromcliifolia 



Pinna? lanceolate or linear-lanceolate. 



Pinna: with salient teeth 7. 0. banksii folia 



Pinnae with appressed teeth or entire. 



Larger pinnae more than 25 cm long 8. O.javanica 



Larger pinnae less than 20 cm long 9. 0. vachelii 



1. Osmunda regalis L. 



Stipes tufted, usually more than 30 em high; frond, excluding stipe 

 50 to 120 cm high, 30 cm or more broad, bipinnate, a few apical pinnae 

 fertile; pinna* approximately opposite, short-stalked; pinnules subsessile, 

 3-5 cm long, about 1 cm broad, the sides parallel, obtuse, unequally trun- 

 cate at the base, finely serrulate, subcoriaceous, glabrous; fertile pinnules 

 reduced, cylindrical, lobed or pinnate. 



Var. japonica Thunb. (Plate XL) 



Usually smaller than the typical form, sterile and fertile fronds dis- 

 tinct ; the sterile pinnules gradually narrowed upward from a broad base. 



Cosmopolitan, but unknown in the Philippines, Malaya and Australia: the 

 variety japonica is the common form from Japan to India. 



2. Osmunda mildei C. Chr. (0. bipimuita JIoolc.) 



A rather smaller fern than 0. regalis, upper sterile pinna? entire, the 

 others with an entire distal segment about 3 cm long and 10 to 14 mm 

 broad with rounded apex, lobed below this, and below the lobes bearing 

 pinnules 10 to 17 mm long, about I) mm broad, entire, rounded at both 

 ends and adnate to the winged rachis, fertile pinnae typically at base of 

 frond, but often found elsewhere, or almost the whole frond fertile. 



Hongkong and adjacent mainland. 



