[Vol. 9 

 176 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



only rival among the echinate forms is I. Brochoni Motel., in 

 which the spines are far sharper. 



Most of the Alaskan material is immature, but in some of the 

 specimens mature spores can be found in the soil. The collec- 

 tion of Coville & Kearney 2336 appears to be made of smaller 

 plants of the species, their 2337 of larger specimens, with no 

 notable differences in spores, sculpture, etc. 



SECT. 3. CRISTATAE 



3. CRISTATAE. Forms with 2 or 3-lobed corms; producing 

 megaspores with tubercles or spines, somewhat extended into 

 ridges, tending toward branching crests on basal face; micro- 

 spores rough or smooth. 



KEY TO SPECIES 



A. Corms 3-lobed. 



a. Leaves very slender 44. I. tripus 



b. Leaves stout, mucronate 45. I. Savatieri 



B. Corms 2-lobed. 



a. Amphibious forms, with stomata; peripheral strands present 



or absent. 

 a. Megaspores with very crowded prominences. 



I. Leaves numerous (25-200), usually with peripheral 



strands .. 46. I. Eatoni 



II. Leaves few (8-25), peripheral strands lacking 47. I. saccharata 



/3. Megaspores with less densely crowded prominences. 

 I. Sculpture consisting of spines somewhat extended to 

 form jagged crests. 



1. Smaller form, leaves 10-30, 9-30 cm. long 48. I. riparia 



2. Larger form, leaves 15-75, 10-45 cm. long 



48a. I. riparia var. canadensis 



II. Sculpture consisting of tubercles somewhat extended 

 to form rounded ridges. 



1. Leaves long, more than 16 cm., with peripheral strands 



49. I. Pringlei 



2. Leaves short, less than 8 cm., lacking peripheral strands 



50. I. Flettii 



b. Submerged forms, lacking stomata and peripheral strands, 

 o. Velum narrow, covering about % of sporangium. 



I. Megaspores with somewhat confluent, but little 



anastomosing, crests 51. I. lacustris 



II. Megaspores with crests, forming irregular network on 



basal face .. 5-2. I. ocddentalis 



/3. Velum wider, covering %-% of sporangium 53. I. Piperi 



44. I. tripus A. Br. Monatsber. K. Akad. Wiss. Berlin, 544. 

 1868; Motel. & Vendr. Actes Soc. Linn. Bord. 36: 361. 1883. 



/. pkaeospora Dur. Bull. Soc. Bot. Fr. 9:103. 1864. fide 

 Motel. & Vendr. 



