[Vol. 9 



106 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



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II. Leaves long, more than 20 cm. in length. 



I. Peripheral strands and stomata present 22. I. Gardneriana 



II. Peripheral strands and stomata absent 23. I. elatior 



p. Velum complete. 



I. Amphibious; leaves 7 cm. long 24. I. Muelleri 



II. Terrestrial. 



1. Leaf-bases persistent, conspicuous, usually spiny 25. 7. histrix 



2. Leaf bases sometimes persistent, not conspicuous. 



"Leaves more than 13 in number, longer than 8 cm. ..26. I. Nuttallii 

 "Leaves less than 15 in number, less than 8 cm. 27. I. Orcuttii 



b. Corms 2 lobed. 



a. Velum complete. 



I. Megaspores dark when wet, small-tuberculate. 



1. Megaspores large, more than Goo ^ in diameter 28. 1. humilior 



2. Megaspores small, less than 480 /x in diameter. 

 "Leaves less than 7 cm. long; megaspores more 



than 360 /x .. 29. I. melanospora 



**Leavea more than 7 cm. long; megaspores less 



than 360/i - 30. I. lithophila 



II. Megaspores white or creamy. 



1. Megaspores marked with large warts. 



*Warta always simple 31. I. flaccida 



Warts confluent into bold ridges on the basal face -.31a. I. flaccida 



var. a' at a. 



2. Megaspores marked with very Ioav tubercles. 



Stomata present 32. I. LecWeri 



Stomata lacking 33. I. triquetra 



p. Velum narrow, usually covering not more than one- 

 third of sporangium. 

 I. Megaspores with tubercles frequently confluent into wrinkles. 



1. Amphibious; stomata and peripheral strands usually 

 evident. 

 Megaspores more than 420 /x in diameter 31. I. Howcllii 



Megaspores less than 420 /x in diameter 34a. L Howellii 



var. minima 



2. Submerged; stomata few, peripheral strands lacking. 

 "Leaves more than 6 cm. long, slender $5. I. Bolandcri 



Leaves less than 6 cm. long, stout 35a. I. Bolandcri 



var. pygmaea 



II. Megaspores with chiefly simple tubercles. 



1. Peripheral strands lacking 36. I. Tuerckheimii 



2. Peripheral strands present. 

 Megaspores less than 480^ in diameter. 



t Surface of spore smooth or with large simple 



tubercles. „ 37. I. mcxicana 



tt Surface of spore with small tubercles, sometimes 



confluent. 38. I. mt lannpod ' 



**Megaspores more than 480 ^ in diameter 39. I. Butler % 



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I. Isoetes Welwitschii A. Br. in Kuhn, Fil. Afr. 196. 1868; 

 A. Br. Sitzb. Naturf. Fr. Berlin, 7. 1867; Motelay & Vendrycs, 

 Actes Soc. Linn. Bord. 36 : 388. 1883. 



Calamaria Welwitschii Kuntze, Rev. Gen. PI. 2: 828. 1891-93. 



Corm 3-lobed; leaves 6-15, rigid, straight or slightly curved, 

 firm, very fine, pale green surrounded at base by some dark 

 scales; stomata numerous; peripheral strands 4 primary, acces- 

 sories none in front, 4 on each side in back ; velum very narrow, 



