54 



ISOETACEAE. 



VOL. I. 



ii. Isoetes Gravesii A. A. Eaton. 

 Grave's Quilhvort. Fig. 128. 



Isoetes Gravesii A. A. Eaton, Fernwort 

 Papers 14. 1900. 



Polygamous; leaves 20-150, s'-n' 

 long and i"-ia" in diameter, erect, 

 reddish or dark green ; sporanges 

 with an abundance of light brown 

 cells, i- covered by the velum ; 

 macrospores 351-405 /* in diameter, 

 the upper hemisphere depressed, 

 covered \\ith short truncate single 

 columns ; microspores 22-30 v- long, 

 high-cristate or tuberculate. 



Edges of ponds and streams ; Massa- 

 chusetts and Connecticut. 



12. Isoetes melanopoda J. Gay. Black-based 

 Quilhvort. Fig. 129. 



/. melanopoda J. Gay, Bull. Soc. Bot. France, n : 102. 1864. 

 Terrestrial with a subglobose deeply 2-lobed trunk. 

 Leaves 15-60, slender, erect, bright green, with a black- 

 ish shining base, s'-iS' long, triangular, bearing stfomata 

 throughout, well developed peripheral bast-bundles, thick 

 dissepiments and small air cavities within ; ligule tri- 

 angular, awl-shaped; sporange mostly oblong, spotted, 

 with a narrow velum ; polygamous ; macrospores 250- 

 400 /" in diameter, with low more or less confluent 

 tubercles, often united into worm-like wrinkles, or 

 almost smooth ; microspores 23-30 M long, spinulose. 



In moist prairies and overflowed fields, Illinois to Iowa 

 Oklahoma and California. 



13. Isoetes Butleri Engelm. Butler's Quillwort. 



Fig. 130. 



Isoetes Butleri Engelm. Coult. Bot. Gaz. 3: i. 1878. 



Terrestrial from a subglobose trunk. Leaves 8-60, 

 bright green, paler at the base, triangular, 3 '-7' long, 

 bearing numerous stomata, and with well developed 

 peripheral bast-bundles, thick dissepiments and small 

 air cavities within ; sporange usually oblong, spotted ; 

 velum very narrow or none ; ligule small, triangular ; 

 dioecious ; macrospores 400-630 /< in diameter, with 

 distinct or confluent tubercles; "microspores 28-34 M 

 long, dark brown, papillose." 



On rocky hillsides, Illinois and Kansas, southward to 

 Tennessee and Oklahoma 



