QUILLWORT FAMILY. 

 Isoetes echinospora robiista Engelm. Trans. St. Louis Acad. 4: j8o. i88a. 



Much larger than the preceding, leaves 25-70 or even more, s'-ia* lone with itiiiniliii 



throughout. With the preceding. 



47 



Isoetes echinospora Boottii Kngehn. in A. Gray, Man. Kd. 5, 676. 1867. 



Leaves 12-20, soft, erect, bright green, 4' -5' long, with a few stomata near their tip* i 

 tiearly orbicular, with pale spots, two-thirds or inure o.vi-n-d l.y th<- v.-luin macrtMtxin* o 



in diameter, with longer and more slender simple si.imr., 

 Middlesex county, Massachusetts, usually submerged. 



Isoetes echinospora muricata ^Durieu) Engelm. in A. r.ray. Man K<1. 5, 676. 1867. 

 Isoetes muricata Durieu, Bull. Soc. Bot. France, 11: 100. 1864. 



Leaves 15720, flaccid, bright green, 6'-i2' long, bearing few stomata ; sporanRe broadly ova) with 

 pale-spots, about one-half covered by the velum ; mai-rospi.n - |... s*>'' in <li;n: 

 and more confluent, almost crest-like spinules ; mk-n>sp<m Sightly r..u K h im th<- rdffr*. 



Submerged in running water in tributaries of Mystic I'mid, Middlesex ounr 



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, n'-^' long, quadrangular, bearing nu- 

 merous stomata; sporange oblong, unspotted, with a 

 narrow velum covering only one-fourth or one- 

 third of its surface ; peripheral bast bundles want- 

 ing ; ligule triangular, rather short; macrospores 

 400-470 fj. 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 Kn^clm. River- 

 bank Quillwort. <Fig. 1 06.) 



Isoetes riparia Kngi-lm.: A. 

 1846. 



Fl>rm, 



Amphibious or uliginous, usually emcred 

 when mature ; leaves 15-30, deep green, rather 

 rigid, 4'-8' long, quadrangular, bearing numer- 

 ous stomata ; peripheral bast-bundle* wanting ; 

 ligule rather short, triangular ; tporange mostly 

 oblong, distinctly spotted with group* of brown 

 cells, one-fourth or rarely one-half covered with 

 the velum ; macrospores 45- 6 5 f ' n <lneter. 

 marked with distinct or anastomosing jagged 

 crests or somewhat reticulate on the lower side. 

 microspores 28-32 ft long, more or less tubercu- 

 late. 



Borders of the lower Delaware River to Maine. 



