QUILLWORT FAMILY. 47 
Isoetes echindspora robusta Engelm. Trans. St. Louis Acad. 4: 380. 1882. 
Much larger than the preceding, leaves 25-70 or even more, 5/-12' long, with abundant stomata 
throughout. With the preceding. 
Isoetes echinéspora Boottii Engelm. in A. Gray, Man. Ed. 5, 676. 1867. 
Leaves 12-20, soft, erect, bright green, 4’-5' long, with a few stomata near their tips; sporange 
nearly orbicular, with pale spots, two-thirds or more covered by the velum ; macrospores 390-500/4 
in diameter, with longer and more slender simple spinules ; microspores 26-304 long. In ponds, 
Middlesex county, Massachusetts, usually submerged. 
Isoetes echindspora muricata | Durieu) Engelm. in A. Gray, Man. Ed. 5, 676. 1867. 
Isoetes muricata Durieu, Bull. Soc. Bot. France, 11: 100. 1864. 
Leaves 15-20, flaccid, bright green, 6’-12' long, bearing few stomata ; sporange broadly oval, with 
pale-spots, about one-half covered by the velum ; macrospores 400-580! in diameter, with shorter 
and more confluent, almost crest-like spinules; microspores 28-32!, slightly rough on the edges. 
Submerged in running water in tributaries of Mystic Pond, Middlesex county, Mass. 
4. Isoetes saccharata Engelm. Sugary 
Quillwort. (Fig. 105.) 
Isoetes saccharata Engelm. in A. Gray, Man Ed. 5, 676. 
1867. 
Amphibious or uliginous with a flat depressed 
trunk. Leaves 10-20, olive-green, pale at the base, 
spreading, 2’-3’ long, quadrangular, bearing nu- 
merous stomata; sporange oblong, unspotted, witha 
narrow velum covering only one-fourth or one- 
third of its surface; peripheral bast bundles want- 
ing; ligule triangular, rather short; macrospores 
400-470 “ in diameter, with very minute distinct 
or rarely confluent warts as if sprinkled with grains 
of sugar ; microspores papillose, 24-28” long. 
_In mud overflowed by the tides, Wicomico and Nan- 
ticoke Rivers, eastern Maryland. 
5. Isoetes riparia Engelm. River- 
bank Quillwort. (Fig. 106.) 
Tsoetes riparia Engelm.; A. Br. Flora, 29: 178. 
1846. 
Amphibious or uliginous, usually emersed 
when mature ; leaves 15-30, deep green, rather 
rigid, 4/-8’ long, quadrangular, bearing numer- 
ous stomata ; peripheral bast-bundles wanting ; 
ligule rather short, triangular ; sporange mostly 
oblong, distinctly spotted with groups of brown 
cells, one-fourth or rarely one-half covered with 
the velum ; macrospores 450-650 / in diameter, 
marked with distinct or anastomosing jagged 
crests or somewhat reticulate on the lower side; 
microspores 28-32 long, more or less tubercu- 
late. 
Borders of the lower Delaware River to Maine. 
