ISOETACBAB (QUILLWORT FAMILY) 



61 



I. Dodgei, Gjmo- 

 spore X 15. 



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

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

 — Our largest species. 



9. I. Gravdsii 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, ^-l covered by the velum ; gynospores 351- 

 405 |U in diameter, the upper hemisphere depressed, covered with short truncate 

 single columns ; androspores 22-30 /x (average 26 fi) 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, J-| covered by the velum ; gynospores 

 500-675 ij. (average 560 /x) in diameter, sparsely beset with 

 irregular often anastomosing walls ; androspores 22-44 /j. 

 (average 32 fi) long, wrinkled. (7. riparia, var. canadensis 

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

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



Var. Robblnsii A. A. Eaton. Leaves 15-30, 10-38 cm. long, 1-1.5 mm. wide, 

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

 brown cells ; gynospores 460-600 /j. (average 500 /j.) in diameter, thickly beset 

 with anastomosing jagged walls ; androspores 28.7-32.8 /j. long, rough or slightly 

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

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



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

 ter, light green ; sporangia unspotted, J or less indusiate ; gynospores 360-570 /j. 



(average 450 /i) in diameter, honeycomb-reticulated with 

 thin walls ; androspores 24-29 yn 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. vdlida Engelm. Plants larger ; leaves 50-100, 3-6 dm. 

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

 J-f- indusiate ; gynospores 320-570 fi (average 480 n) in diameter ; androspores 

 24-30 ^|. (average 28 fi) long, blunt-spinulose. — N. J. to Va. 



Var. fontkna 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 400-750 /m (average 500 /i) 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, chestnut or black at base, with numerous peripheral bast- 

 bundles ; sporangia less than J- indusiate, thickly spotted ; 

 gynospores 260-400 ^a (average 330 /x) in diameter, nearly 

 smooth or with low often confluent tubercles; androspores 

 2.3-30 /i (average 25 /j.) long, spinulose. — Inundated fields and 

 shallow ponds,'lll. and la. to Okl. and Cal. Fig. 31. Variety 

 PALLIDA Engelm. of the Southwest, occasionally found mixed 

 With the type in our range, differs only in having pale leaf-bases. 



13. I. ButlSri Engelm. Dioecious; leaves 8-60, 7.5-22 cm. long, 0.5 mm. 



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 m (average 570 fj.) in diameter, roughened 

 with very small warts or fragmentary crests ; androspores 28-34 /x 

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

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



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



form of the species. 



30. I. Engelmanni. 

 Gynospore x 15. 



31. I. melanopoda. 

 Gynospore x 15. 



82. I. Butleri. 

 Gynospo're X 15. 



