46 ISOETACEAE. 
1. Isoetes lacistris L. Lake Quillwort. (Fig. 102.) 
Tsoetes lacustris Y. Sp. Pl. 1100. 1753. 
Tsoetes macrospora Durieu, Bull. Soc. Bot. France, 11: 
ior. 1864. 
Submerged or rarely above water in dry seasons ; 
leaves 10-25, rigid, rather thick, scarcely tapering, 
dark or olive green, obtusely quadrangular, 2’-6’ 
long ; stomata none ; peripheral bast-bundles want- 
ing ; sporange orbicular or broadly elliptic, un- 
spotted ; velum rather narrow; ligule triangular, 
short or somewhat elongated; macrospores 500- 
800 . in diameter, marked all over with distinct or 
somewhat confluent crests, and bearing three con- 
verging ridges ; microspores 35-46 / long, smooth. 
In 1°-5° of water, Labrador to the Northwest Terri- 
tory, south to eastern Massachusetts and New Jersey. 
Also in Europe and Asia. 
2. Isoetes Tuckermani A. Br. Tuckerman’s Quillwort. (Fig. 103.) 
/ 
Tsoetes Tuckermani A. Br. in A. Gray, Man. Ed. 5, 
676. 1867. 
* Submerged or rarely partly or wholly emersed 
during very dry seasons; leaves 10-30, very slen- 
der, tapering, olive-green, quadrangular, 2/—3/ 
long, without peripheral bast-bundles, the outer 
recurved ; sporange oblong, mostly white, its upper 
one-third covered by the velum ; macrospores 440- 
560 in diameter, with wavy somewhat parallel 
and branching ridges on the upper half, separated 
by the three converging ridges, the lower covered 
with an irregular network ; microspores 26-32 
long, nearly smooth. 
In ponds, Newfoundland to Middlesex county, Mass- 
achusetts, clustered in shallow water. 
3. Isoetes echinospora Braunii (Durieu) Engelm. Braun s Quillwort. 
(Fig. 104.) 
TIsoetes Brauniti Durieu, Bull. Soc. Bot. France, 11: 101. 
1864. 
Isoetes echinospora var. Braunti Engelm, in A, Gray, 
Man. Ed. 5, 676. 1867. 
Submerged or in dry seasons emersed, leaves 12- 
25, tapering, soft, reddish-green, 3/-6’ long, with- 
out peripheral bast-bundles, bearing stomata only 
toward the tip; sporange orbicular or broadly 
elliptic, spotted, one-half to three-fourths covered 
with the velum; macrospores 400-500 “ in diameter, 
covered with broad spinules which are often 
slightly confluent and incised at the tips; micro- 
spores 26-30 « long, smooth. 
Labrador and Greenland to Alaska, south to New 
Jersey, Pennsylvania and Utah. 
