ISOETACEAE: 17 



Family 2. SELAGINELLACEAE Underw. 

 1. SELAGINELLA Beauv. 



Stem-leaves all alike, many-ranked; 1. S. rupestris. 



Stem-leaves of 2 kinds; 4-ranked, spreading in 2 planes. 2. S. apus. 



1. Selaginella rupestris (L.) Spring. M. p. 26. Dry roeks. Summer. 



Philadelphia— Above Manayunk, Mart. (B. C). Bucks— Nockamixon 

 (Fr.). Chester— (P.). Lancaster— York Furnace (He.) (Ke.). Berks— 

 (P.). Northampton— Easton (P.). 



Hunterdon — ]\Jilford (C). './ ."! , u ]' , ,--, 



New Castle— Rocky Eidge, Point Lookout. 



2. Selaginella apus (L.) Spring. M. p. 27. Low shady places. Summer. 



Family 3. ISOETACEAE Underw. Quillwort Family. 



1. ISOETES L. Quillwort. 



Submerged or rarely emersed in very dry seasons; leaves quadrangular, 

 without peripheral bast-bundles. 

 Stomata wanting; macrospores crested. 1. 7. lacustris. 



Stomata present; macrospores echinate. .. 2. 7. echinospora var. 



Amphibious or submerged only in earlier stages ; stomata always present on 

 the quadrangular leaves. 

 Peripheral bast-bundles wanting. 3. 7. riparia. 



Peripheral bast-bundles present. 



Macrospores sparsely covered with irregular crests. 



4. I. Dodgei. 

 Macrospores with honeycomb-like reticulations. 



5. I. En'gelmanni. 



1. Isoetes lacustris L. M. p. 27. Ponds. Summer. 



Delaware— Darby (B. Sm.).f 

 2a. Isoetes echinospora Braunii (Durieu) Engelm. M,. p. 28. Ponds. 

 Autumn. 



Ocean — Toms River (C). 

 26. Isoetes echinospora robusta Engelm. M. p. 28. Ponds. Autumn. 



Bucks — Durham, Ruth (Pr.) 



3. Isoetes riparia Engelm. M. p. 28. Gravelly shores. Summer. 



Philadelphia— Jorresdale (Wn.). Bucks— Andalusia, Mart. (Fr.), Tul- 

 lytown (Fr.). Delaware — Tinicum (Fu.), banks of the Delaware (B. Sm.). 

 Camden — Cooper's Point, Mart. (B. C). Gloucester — Delaware, oppo- 

 site Chester (Le.), Timber Creek (Te.). 

 New Castle— River shore, B. Hoopes, Cariby, Commons. 

 i. Isoetes Dodgei A. A. Eaton. M. p. 29. Mud flats. Summer. 



Bucks— Point Pleasant, Dr. Geo. Best (Fr.). , 



5. Isoetes Engelmanni A. Br. M. p. 29. Shallow ponds and ditches. 

 Autumn. 

 Bucks— Near Perkasie (Fr.), Riegelsville, E. A. Eau (Fr.). Lancaster 

 — Smithville (Ca.). 

 Camden — Camden (C). 

 New Castle— Thompsons, Farnhurst, Ogletown. 



