[Vol. S 



192 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



KEY TO SPECIES 



A. Corms 2-lobed. 



a. Submersed forms, stomata none or rare, 

 o. Megaspores chiefly 600-800/i in diameter. 



I. Spore markings irregular, sharp crests 54. I. macrospora 



II. Spore markings prominent, rounded ridges 



54a. I. macrospora f. hieroglyphica 



ft. Megaspores chiefly 460-600 p in diameter 55. I. Tuckermani 



b. Amphibious forms, stomata at least near leaf tips. 



a. Leaves less than 18 cm. long 56. I. fovcolata 



ft. Leaves chiefly more than 18 cm. long. 



I. Megaspores large, over 580 /j. in diameter 57. I. Martii 



II. Megaspores usually less than 580 /j. in diameter. 



1. Spore surface reticulate with narrow ridges, 400- 

 570 fj, in diameter. 



*Velum narrow, covering less than % of sporangium_55. I. Engelmanni 



**Velum covering %-% of sporangium 58a. I. Engelmanni 



var. caroliniana 



2. Spore surface reticulate with rounded ridges, 360- 



490 fj. in diameter .. 59. I. azorica 



B. Corms 3-lobed. 



a. Aquatic, lacking velum. 



a. Peripheral strands present 60. I. japonica 



ft Peripheral strands lacking 61. I. Wormaldii 



b. Terrestrial, with complete velum 62. I. Duriaei 



54. I. macrospora Dur. Bull. Soc. Bot. Fr. 11: 101. 1864; 

 Clute, Fern Allies, 224. 1905; Eaton in Gray, Manual, ed. 7, 58. 

 1908; Maxon in Britton & Brown, 111. FL, ed. 2, 1: 50. 1913. 



7. lacustris Engelm. Trans. St. Louis Acad. Sci. 4: 377. 1882; 

 Motel. & Vendr. Actes Soc. Linn. Bord. 36: 325. 1883; Baker, 

 Jour. Bot. 18: 67. 1880. 



7. Harveyi Eaton, Fernwort Papers, 11. 1900. 



7. Tuckermani var. Harveyi Clute, Fern Allies, 226. 1905. 



7. heterospora Eaton, Fernwort Papers, 8. 1900. 



7. macrospora var. heterospora Eaton, Rhodora 10: 42. 1908. 



7. Tuckermani heterospora Clute, Fern Allies, 227, 260. 1905. 



Corm 2-lobed ; leaves usually 13-40, occasionally more numer- 

 ous, 5-22 cm. in length, rigid, slightly to decidedly coarse, ab- 

 ruptly tapering to apex; peripheral strands lacking; stomata ab- 

 sent or very rare; ligule short triangular; sporangia 3-5 mm. 

 long, with narrow velum; megaspores white, 600 (550)-800 j.i, or 

 more in rare cases, with sculpture of irregular ridges more or less 

 parallel, with little confluence on upper faces, anastomosing, 

 sometimes with clear reticulations on the lower face ; microspores 

 33-45 (50) (j long, short spinulose. 



Distribution: Newfoundland west to Minnesota. 



