NOTES ON ISOETES. 



By A. A. Eatox. 



Some years ago I received from Mr. C. V. Piper two 

 collections of Isoctes that were found to be undescribed. 

 Both of these were subsequently duplicated by other 

 collectors, and have been found to hold their character- 

 istics. They may be characterized as follows : 



I. piperi Sp. now 



Submerged ; bilobed ; leaves 8-25. 2-7 cm. long. 2 mm. 

 wide, cylindrical, slightly winged J their height, rigid, 

 erect, abruptly pointed, without stomata or bast-bundles ; 

 velum broad, § or more indusiate ; sporangia unspotted ; 

 gynospores 570-780//. average 700//, thickly covered with 

 short distinct warts, the equator nearly obsolete ; andro- 

 sporangia irregularly scattered among the gynosporangia, 

 the spores 36-45//. sigmoid crested. 



Green Lake, near Seattle, Washington, C. V. Piper, 

 July 11, 1889 and July 12, 1895. no. 2317. type. — De 

 Alton Saunders, 1900. 



In appearance this resembles the others of the group, 

 and is distinguished from paupcrcula principally by the 

 broad velum, unspotted sporangia and larger spores 

 covered with distinct, smooth, round tubercles instead 

 of convoluted ridges. I dedicate this species to Mr. 

 Piper, who has extended the author many courtesies in 

 his study of the genus. 



I. ECHIXOSPORA VAR. FlETTII, VAR NOV. 



Leaves 10-20, 2-3 mm. in diameter, 5-8cm cm. long, 

 broadly winged below, abruptly pointed, recurved, with 

 many stomata ; velum indusiate ; sporangia spotted ; 

 gynospores 450-600^, average 51OW, very sparsely beset 

 with short, thick, mostly compressed lamellae or blunt 

 spines, occasionally cristate and rarely more or less 

 meandriniform-reticulated ; androspores 28-36//. average 

 32//. spinulose. Differs from any other variety of the 

 species in its very stout leaves, the thick, short, scattered 



