ISOETACEAE (QUILLWOET FAMILY) 



61 



Dodgei. Gj'iio. 

 spore X 15. 



ig, 1-1.5 mm. wide, 



usually scattered among the gynosporangia, the spores 25-30 /i (^average 28 fj.) 

 long, minutely tuberculate. — Borders of ponds and streams, s. N. H. to N. J. 

 — Our largest species. 



9. I. Gravesii A. A. Eaton. Polygamous; leaves 20-150, 12-30 cm. 

 long, 2-3 mm. in diameter, erect, reddish or dark green ; sporangia with an 

 abundance of light brown cells, ^-^ covered by the velum ; gynospores 351- 

 405 /x in diameter, the upper hemisphere depressed, covered with sliort truncate 

 single columns ; androspores 22-30 /a (average 26 /a) long, high-cristate or tuber- 

 culate. — Mass. to Ct. 



10. I. D6dgei A. A. Eaton, Leaves 10-75, the submersed 20-45 cm. long, 

 1.5-2 mm. wide, erect or spiral; emersed 10-15 cm. long, interlaced; stomata 

 many ; bast-bundles usually present ; sporangia sprinkled 

 with light cells, ^-^ covered by the velum ; gynospores 

 500-675 fjL (average 500 fi) in diameter, sparsely beset with 

 irregular often anastomosing walls ; androspores 22-44 fi 

 (average 32 /a) long, wrinkled. (/. riparia, var. canadensis 

 Engelm. ; /, canadensis A. A. Eaton.) — Firm soil, borders 

 of ponds and streams. Me. to B. C, southw. to Pa. Fig. 29. 



Var. Robbinsii A. A. Eaton. Leaves 15-30, 10-38 cm. lonj 

 dark green, rigidly erect, fine-pointed ; sporangia ^-\ indusiate, covered with 

 brown cells; gynospores 460-600 ju (average 500 ^a) in diameter, thickly beset 

 with anastomosing jagged walls ; androspores 28.7-32.8 fi long, rough or slightly 

 papillose. (/. canadensis, var. Bobhinsii A. A. Eaton.) — Borders of ponds 

 and streams, s. Mass. to N. Y. 



11. I. Engelmanni A. Br. Leaves 10-40, 1-4 dm. long, 1-2 mm. in diame- 

 ter, light green ; sporangia unspotted, \ or less indusiate ; gynospores 350-570 /* 



(average 450 ^l) in diameter, honeycomb-reticulated with 

 thin walls ; androspores 24-29 /* long, smooth. — Ponds, 

 streams, and ditches, mostly in clay, N. H. and Vt. to Pa. 

 and Mo; mostly near the coast. Fig. 30. Var. gracilis 

 Engelm. is an attenuate form in shade or deep water. 



Var. valida Engelm. Plants larger ; leaves 50-100, 3-6 dm. 

 tall, 2-3 mm. wide, often with 6 bast-bundles ; sporangia 

 gynospores 320-570 ix (average 480 tx) in diameter , androspores 

 24-30 fx (average 28 ix) long, blunt-spinulose. — N. J. to Va. 



Var. fontana A. A. Eaton. Trunk 1-2 cm. in diameter; leaves 30-50, 

 15-20 cm. long, 2 mm. wide, erect, with many stomata and six large and sev- 

 eral small bast-bundles , velum narrow ; sporangia sparingly spotted with light- 

 brown cells ; gynospores 4U0-750 fx (average 500 ix) in diameter, covered with 

 coarser more or less broken alveolations ; androspores as in the type. — Pa. and 

 Va. ; local. 



12. I. melan6poda J. Gay. Polygamous; leaves 15-60, 1.5-3.5 mm. broad, 

 12-45 cm. tall, cliestnut or black at base, with numerous peripheral bast- 

 bundles; sporangia less than \ indusiate, thickly spotted; 

 gynospores 250-400 fx (average 330 /a) in diameter, nearly 

 smooth or with low often confluent tubercles ; androspores 

 23-30 /i (average 25 /x.) long, spinulose, — Inundated fields and 

 shallow ponds," 111. and la. to Okl, and Cal. Fig. 31. Variety 

 PALLIDA Engelm. of the Southwest, occasionally found mixed 

 ^7ith the type in our range, differs only in having pale leaf-bases. 



13. L Butleri Engelm. Dioecious; leaves 8-60, ".5-22 cm. 

 in diameter, rigid, triangular-setaceous, with wide dissepiments, narrow air- 

 canals, and four stout bast-bundles ; sheaths granular on the 

 backs ; velum none or very narrow ; sporangia mostly spotted ; 

 gynospores 400-630 p. (average 570 fx) in diameter, roughened 

 with very small warts or fragmentary crests ; androspores 28-34 a* 

 long, coarsely tubercled. — Moist hillsides and shallow depres- 

 sions, 111. and Kan. to Tenn. and Okl. Fig. 32. Var. immactlXta 



Engelm, is a form without spots on the sporangia, growing wita the typical 

 form of the species. 



30. I. Engelmanni. 

 Gynospore x 15. 



I. melannpoda. 

 Gynospore x 15. 



long, 0.5 mm. 



82. I. Butleri. 



Gynospore X 15. 



