4 8 



ISOETACEAE. 



O 







6. Isoetes Engelmanni A. Br. Engelmarm's Quillwort. (Fig. 107.) 

 fsoe/es Engelmanni A. Br. Flora, 29: 178. 1846. 



Amphibious, usually partly emersed when ma- 

 ture. Leaves 25-100, light green, quadrangular, 

 tapering, g'-zo' long, bearing abundant stomata ; 

 peripheral bast-bundles present ; sporange oblong 

 or linear-oblong, unspotted ; velum narrow ; ma- 

 crospores 400-520 ," in diameter, covered with 

 honeycomb-like reticulations ; microspores 24-28 // 

 long, mostly smooth. 



In ponds and ditches, rooting in mud, Maine to Del- 

 aware and Pennsylvania, Illinois and Missouri. 



Isoetes Engelmanni valida Engelm. in A. Gray, Man. 



Ed. 5, 677. 1867. 



Leaves 50-200, keeled on the upper side, iS'-25' long ; 

 sporange linear-oblong, 4"-9" long, one-third to two- 

 thirds covered by the velum ; macrospores 320-480 /* in 

 diameter; microspores 24-27^ long, spinulose. War- 

 riorsmark, Cornwall and Smithville, Pa., and Wilming- 

 ton, Del. 



Isoetes Engelmanni gracilis Engelm. in A. Gray, Man. Ed. 5. 677. 1867. 



Leaves 8-12. slender, g'-i2' long ; bast-bundles often quite small or only two present ; spores as 

 in the typical form. Southern New England to New Jersey. 



7. Isoetes melanopoda J. Gay. Black-based 

 Quillwort. (Fig. 108.) 



Isoetes 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 

 blackish shining base, s'-iS' long, triangular, bear- 

 ing stomata throughout, well developed peripheral 

 bast-bundles, thick dissepiments and small air cavities 

 within; ligule triangular, awl-shaped; sporange mostly 

 oblong, spotted, with a narrow velum ; polygamous ; 

 macrospores 250-400 fi in diameter, with low more or 

 less confluent tubercles, often united into worm- 

 like wrinkles, or almost smooth ; microspores 23-28," 

 long, spinulose. 



In moist prairies and overflowed fields, Illinois to Iowa, 

 Missouri and Texas. 



8. Isoetes Butleri Engelm. Butler's Quill- 

 wort. (Fig. 109.) 



Isoetes Butleri Engelm. Coult. Bot. Gaz. 3:1. 1878. 



Terrestrial from a subglobose trunk. Leaves 8-15, 

 bright green, paler at the base, triangular, $'-]> 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 500-630/4 in diameter, with 

 distinct or confluent tubercles; "microspores 28-34^ 

 long, dark brown, papillose." 



On rocky hillM.U-,. St. l.,,,,i s . Missouri, and on saline 

 flats Indian Term. >ry. 



