76 American Fern Journal 



ISOETACEAE. Quillwort Family. 



Plant consists of a tuft of short hollow cylindrical 

 grass-like p3inted leaves with sporangia near their axils; 

 stem short, tuber-like, 2-3-lobed; roots a dense tuft. 

 Leaves spirally arranged but very close. Sporangia 

 large, orbicular or ovoid, plano-convex, thin, 

 more or less covered by the leaf. Megaspores in the 

 sporangia of the outer leaves, large globular; micro- 

 spores in the sporangia of the inner leaves, minute, pow- 

 dery, grayish, obliquely oblong and triangular. Plants 

 submerged or in swampy places. There is only the 

 following genus. 



ISOETES. Quillwort. 



Description the same as for the family. (Greek isos 

 equal, etos = the year; because they are evergreen.) 

 Some species are grown as house plants, since they do 



well in aquaria. 



A. Cross- tin of 181V81 with f .mn i>;rip'iTil In bundle?. 



B. Lea\ > 1-2 in. long; megaspores covered frith short blunt spiuulcs. 



1. 2". minima. 

 BB. Leaves 2-8 in. long; megaspores covered with ridges or ere >. 



2. I. HowelHi. 



AA. Cross-section of leaves with 3 peripheral bast bundles; megaspores 



covered with irregular warts. 3. I. NuttalliL 



AAA. Cross-section of leaves without peripheral bast bundles. 



C. Plants quite submerged the year round. 



D. Megaspores with irregular ridges. 4. /. paupercula. 



DD. M :aspores with distinct, low warts. 5. I. Piperi. 

 I)DD. Megaspores with minute dots which rarely join to form 

 wrinkles. 6. /. Bolandcri. 



CC. Plants only partly submerged or else submerged only part of the 



year. 



E. Megaspores covered with broad spinoles which arc often forked 

 or toothed or sometimes confluent leaves slender. 



7a. /. ahinospora Braunii. 

 EE. Megaspores covered with few short, wart -like spines: leaves 



stout. 71,. j. echinospora Flrttii. 



MINIM 



Plant terrestrial, in dump soil. Leaves 6-12, 1-2 in. 



