60 ISOETACEAE (QUILLWORT FAMILY) 



gynospores 486-720 p. (average 600 fi) in diameter, sparingly covered with thick 

 vermiform subcontluent or reticulated ridges except just beneath the equator ; 



androspores 31-44 fx (average 36 jx) long, verrucose. — Ponds 

 and lakes, N. 8., Que., and Me. Fig. 26. 



4. I. foveolata A. A. Eaton. Polygamous ; leaves 50-150, 

 5-15 cm. long, 2 mm. in diameter, round, pinkish or olive- 

 " green ; sporangia thickly dark-spotted, ^\ covered by the 



GvnosD<^S X 15'''' ^'^^^"' ' gynospores 380-560 /. (average 440 m) in diameter, 



^ ^ ■ the lower surface covered with little holes, the upper a 



little more open ; androspores 22-35 jx long, reticulated or 



papillose. '— Ponds and river borders ; N. H. and Ct. Fig. 



27. 



Var. plen6spora A. A. Eaton. Leaves 30-110, 1.5 mm. 



27. I. foveolata. Gyuo- in diameter, 20-40 cm. long ; sporangia thickly dark-spotted, 



spore X 15. i"! covered by the velum ; gynospores white or ashy, 450- 



600 fj. (average 510 fx) in diameter, covered with tall thin 



mostly honeycomb-reticulated walls ; androspores 27-33 fx long, finely granular 



or tuberculate. — Gravelly shores of ponds in a thin layer of silt, s. e. Mass. 



5. I. riparia Engelm. Often polygamous; leaves 10-30, 1-3 mm. in diam- 

 eter, 10-25 cm. long, erect, dark green ; sporangia densely spotted, i-| covered 

 by the velum ; gynospores 450-756 ix (averaging 570 fx) in diameter, covered with 

 high isolated, united, or reticulated jagged crests ; androspores 28-32 fx (average 

 29 yu) long, sparingly tubercled. — Tidal shores of Del. R., in gravel. — A species 

 misinterpreted in the past, and seemingly of restricted range. 



6. L saccharata Engelm. Leaves 1(3-30, 1-2.5 mm. in diameter, 3-25 cm. 

 long, spreading or recurved ; velum very narrow to half covering the thickly 

 spotted sporangium ; gynospores 420-510 ix (average 480 /x) in diameter, covered 

 with low granules, reticulated walls or tall rough crests ; androspores 22-30 /x 

 (average 28/i) long, sparingly papillose. — Fresh-water tidal flats, n. arm of 

 Chesapeake Bay and Del. R. — Very variable and closely approaching the last in 

 some of its forms. 



Var. Amesii A. A. Eaton. Trunks 2-5-lobed ; leaves 8-30 cm. long, 1-1,5 mm. 

 in diameter, slender, finely pointed, quadrangular ; sporangia with few spots, 

 ^1 covered by the velum ; gynospores 420-600 ix (average 510 ix) in diameter, 

 marked with fine granules and thin short often reticulated walls; androspores 

 28-32 /i long. — Gravelly shores overlaid -by fine silt, chiefly in shallow water, 

 s. Mass. to N. Y. 



7. I. echin6spora Dur. Leaves 10-30, 5-15 cm. long, 1.5-2 mm. broad, 

 dark green, finely pointed ; velum about one half covering the sporangium ; 

 gynospores 350-560 /i (average 500 ix) in diameter, covered with simple or 

 forked spinules ; androspores 26-30 ix long, smooth. — Eu. — A species repre- 

 sented in America by the following varieties. 



Var. Braiinii (Dur.) Engelm. Differs from the type in having stomata on 

 the leaves, a broader velum, spotted sporangium, and not rarely broad jagged 

 crests on the gynospores. (Var. ro6?<s«a Engelm.; 7. Br-ottii 

 A. Br.) — Muddy or sandy river and pond borders, Gasp6 

 Co., Que. to B. C, s, to Cal, and Pa. ; variable. Fig. 28. 



Var. muricata (Dur.) Engelm. Submersed leaves 10-30, 

 flaccid, spiral, 15-40 cm. long, 1 mm. in diameter ; emersed t h* 



ones 5-8 cm. long, slender, recurved ; sporangia pale-spotted, traunii ^ Gvnospore 

 |-| indusiate ; gynospores 400-620 fx (average 510 /x) in ^ j^ ' ' 

 diameter, covered with slender round spines and flat, i)lunt, 

 or retuse lamellae; androspores 25-31 fx long, smooth or slightly granular. — 

 Firm soil in shallow waters, mostly submersed ; N. S. to n. Me. and N. J, 

 — Grades into the last. 



8. I. Eatbni Dodge. Polygamous ; leaves 30-200, 40-70 cm. long, 3-4 mm. 

 in diameter, flat above; stomata abundant; ba.st-bundles usually present; 

 velum very narrow ; sporangia densely light-brown spotted, not filled by spores ; 

 gynospores round below, upper half depressed, 300-450 /x (average 390 fx) in 

 liameter, with labyrinthiform-convolute ridges ; androsporangia very rare, 



