Flora of the Palo use Region 



fruiting portion quadripinnate below, gradually simpler above; sporangia 

 numerous, crowded, bright yellow. The typical plant grows in geyser for- 

 mations but specimens from near Moscow are referred to this species by its 

 author. 



Order 2. ISOETEAE. 



Plant aquatic, usually submersed, or sometimes growing on 

 moist soil, consisting of a short, 2-3 lobed, flesh}' stem with a 

 dense tuft of fibrous roots and a compact cluster of rush or grass- 

 like leaves: sporangia in small lobes, enclosed in the bases of the 

 leaves; spores of two kinds, large (macrospores) andsmall (micro- 

 spores). 



Family 2. ISOETACEAE. 

 Characters of the Order. 



2. ISOETES. 



Stem a fleshy corm rooting just above the base, surrounded 

 above by the swollen bases of the awl-shaped linear leaves: spor- 

 angia large, enclosed in the bases of the leaves; those of the outer 

 leaves with macrospores, those of the inner with microspores; the 

 sides of the sporangia more or less covered with a fold of the inner 

 side of the leaf base (the velum). 



I. howellii UtfTlui'watid. Leaves 18-50, rather slender, 10-35 cm. long, 

 erect or nearly so, semi-lunate or helmet-shaped in cross section, striate, 

 with abundant stomata above: macrosporangia dark brown, the macrospores 

 bright white, rough with low more or less confluent tubercles; microspor- 

 angia olivaceous, elliptic or oblong, much pitted, 6-S mm. long, partly 

 covered by the narrow wings of the velum, the microspores unsymmetrical, 

 spinulose on the ridges. 



Borders of ponds near Moscow. The species has been redescribed as 

 Isoetes underwoodii Henderson. 



Order 3. FIUCES. 



Plant leafy, vascular: sporangia borne as modified hairs or out- 

 growths from the surface of the leaf, arranged in groups (sori) 

 over the lower or sometimes the upper surface of the leaf; sori 

 with or without a protective covering (the indusium); sporangia 

 opening by means of a more or less complete elastic ring of spec- 

 ialized cells (the annulus); spores of one kind only: vernation 

 circinate. 



Family 3. POLYPODIACEAE. 



Sporangia stalked, surrounded by a more or less complete ver- 

 tical annulus and bursting transversely; sori on the backs or mar- 

 gins of the leaves, with or without indusia, 



