[Vol. 9 

 106 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



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



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



2. 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. I. 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 600 /j, in diameter 28. I. humilwr 



2. Megaspores small, less than 480 ^ in diameter. 

 *Leaves less than 7 cm. long ; megaspores more 



than 360 ^ .. 29. I. melanospora 



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



than 360 ^ 30. I. lithophila 



II. Megaspores white or creamy. 



1. Megaspores marked with large warts. 



*Warts always simple 31. I. flaccida 



**Warts confluent into bold ridges on the basal face Sla. I. flaccida 



var. a'ata. 



2. Megaspores marked w r ith very low tubercles. 



*Stomata present 32. I. LecMeri 



**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^ in diameter 34. I. Howellii 



**Megaspores less than 420 /j. in diameter 34a. I. Hoivellii 



var. minima 



2. Submerged; stomata few, peripheral strands lacking. 



*Leaves more than 6 cm. long, slender 35. I. Bolanderi 



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



var. pygmaea 

 II. Megaspores with chiefly simple tubercles. 



1. Peripheral strands lacking 36. I. Tuerclclieimii 



2. Peripheral strands present. 

 *Megaspores less than 480 /j, in diameter. 



t Surf ace of spore smooth or with large simple 



tubercles. .. 37. I. mexicana 



ft Surf ace of spore with small tubercles, sometimes 



confluent. 38. I. mclannpoda 



**Megaspores more than 480^ in diameter 39. I. Butleri 



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

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

 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, 



