48 ISOETACEAE. 
6. Isoetes Engelmanni A, Br. Engelmann’s Quillwort. (Fig. 107.) 
Isoeles Engelmanni A. Br. Flora, 29: 178. 1846. 
Amphibious, usually partly emersed when ma- 
ture. Leaves 25-100, light green, quadrangular, 
tapering, 9’-20’ 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 4 
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, 18’-25' long ; 
sporange linear-oblong, 4'’-9'’ long, one-third to two- 
thirds covered by the velum ; macrospores 320-480 / in 
diameter; microspores 24-274 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, 9/-12' 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.) 
isos melanopoda J. Gay, Bull. Soc. Bot. France, 11: 102. 
1864. 
Terrestrial with a subglobose deeply 2-lobed trunk. 
Leaves 15-60, slender, erect, bright green, with a 
blackish shining base, 5’-18’ 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 in diameter, with low more or 
less confluent tubercles, often united into worm- 
like wrinkles, or almost smooth; microspores 23-28u 
long, spinulose. 
In moist prairies and overflowed fields, Illinois to Iowa, 
Missouri and Texas. 
8. Isoetes Butleri Engelm. Butler’s Quill- 
wort. (Fig. 109. ) 
Lsoeles Bultleri Engelm, Coult. Bot. Gaz. 3:1. 1878. 
Terrestrial from a subglobose trunk. Leaves 8-15, 
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 500-630 in diameter, with 
distinct or confluent tubercles ; ‘‘ microspores 28-34 ” 
long, dark brown, papillose.”’ 
On rocky hillsides, St. Louis, Missouri, and on saline 
flats, Indian Territory. 
