114 Key to the System of 



561. Creeping plants with mostly dispersed stalk -like 



organs. 



Fruit-masses globular, small, basal, sessile, hardly trans- 

 parent. Pilularia. 2124 



Tufted plants with crowded stalk-like organs. 



Fruit-masses clasped by the base of the stalk-like fronds, 

 transparent. Isoetes. 2125 



ZiVCOPODINAZS. 



562. Leaf-like organs basal. 



Root tuberous ; stem very short, leafless; spore-caselets in a 

 spike, uniform, supported by bract-like organs, longi- 

 tudinally dehiscent. Figure 131. Pliylloglossum. 2126 



Leaf-like organs along the stem and branches ... 563 



563. Spore-caselets accompanied by a second form of fructi- 



fying caselets. 



Leaf -like organs minute, often in four rows, tender ; spore- 

 caselets in spikes, supported by leaf-like or bract-like 

 organs. Selaginella. 2127 



Spore-caselets unaccompanied .by a second form of 

 fructifying caselets ... 564 



564. Spore-caselets comparatively small, one-celled. 



Leaf -like organs small, often densely crowded and rather 

 rigid ; spore-caselets longitudinally dehiscent, singly ax- 

 illary or in spikes, and then supported by leaf -like or 

 bract-like organs. Figure 130. Lycopodium. 2128 



Spore-caselets comparatively large, usually two-celled. 



Leaf-like organs relatively large, scattered, the upper 

 bract-like and divided into two segments ; spore-caselets 

 axillary, sessile, somewhat compressed, broad, two-lobed 

 or exceptionally three-lobed, longitudinally dehiscent. 

 Figure 129. Tmesipteris. 2133 



FXXiXCES. 



565. Spore-caselets firm, seldom very minute, almost or 



quite sessile, opening regularly by a slit ... ... 566 



Spore-caselets very minute, transparent, often on stalk- 

 lets, ruptured irregularly ... ... ... ... 570 



