LTCOPODIALES. 15 



Stems all alike; spores mature in summer; branches simple or none. 

 Sheaths rather loose; branches usually long; stems bushy below, 



attenuate upwards. 3. E. littorale. 



Sheaths appressed; branches usually short. 4. E. fluviatile. 



Stems perennial, evergreen; spikes tipped with a rigid point; stomata in 

 regular rows. 

 Stems rough and tuberculate, prominently ridged. 5. E. hyemale. 

 Stems not tuberculate; sheaths enlarged upwards. 6. E. laevigatum. 



1. Equisetum arvense L. Common Horsetail. M. p. 22. Sandy soil. 



Early spring. 



2. Equisetum sylvaticum L. M. p. 22. Wet, shady places. Spring. 



Philadelphia— Tioga. Station, Mart. (B. C), Gorgas Station (Je.). 

 BwcAs— Nockamixon (Cr.), Quakertown (Le.), Morrisville (Ws.). Dela- 

 ware— Kayer ford (B. Sm.), Concord (W. Tr.). Chester— GreentTee 

 (Pr.). Lancaster— (P.). Lehigh— Salshnrg (Kr.), Lehigh Mountain, 

 Dr. J. B. Brinton (U. C. S.). Northampton— (F.) . 



New Castle — On limestone debris, Hockessin. 



3. Equisetum littorale Kuehl. M. p. 22. Sandy Eiver shores. 



Bucks — Point Pleasant (Fr.). Delaware — (P.). Northampton — 

 Easton (P.). Lancaster and Dauphin— On the Susquehanna (P.). 



4. Equisetum fluviatile L. M. p. 23. In shallow water. Summer. 



^wcts— Nockamixon (He.), Penn Valley (Ja.). Delaware— Chester 

 (B. Sm.). LeM^/i— Slatingdon (Kr.). Northampton— {F.). 

 Camden— 'Kaighn's Point (Ja.). 

 New Castle— Fort Penn (Pr.), Holly Oak, Canhy. 



5. Equisetum hyemale L. Scouring Rush. M. p. 23. Wet places. Spring. 



£mcA:s— Nockamixon (He.) (Ke.), New Hope (Ws.). Delaware— ^aviSk 

 (Sa.), Ridley Creek, near Media (B. Sm.), Concord (W. Tr.), Walling- 

 ford (Wn.). Chester— {F.). Lancaster— Far addse (St.). Lehigh— Co-p- 

 lay (Kr.). Northampton — ^ethleheva. (Pr.). 



Burlington— 'Rirvaingham, Vincentown (C), Medford (Sts.). Glouces- 

 ter— Westyille (He.) (Wn.). ^aiem— Woodstown (He.) (Li.). Cum- 

 berland — Millville (Je.). Monmouth — Keyport (C). 



New Castle— 'NoxentoYfn, Canhy ; Kiemensi, Faulkland, Centerville, 

 Commons; Harvey, Tatnall. 



6. Equisetum laevigatum A. Br. M. p. 23. Along streams and rivers in 



clay soil. 

 Northampton — Easton (P.). 



Order 4. LYCOPODIALES. 



Spores all of one sort and size. Fam. 1. Lycopodiaceae. 



Spores of two sizes. 



Leaves scale-like, 4-many-rank6d, on branching stems. 



Fam. 2. Selaginellaceae. 

 Leaves elongated, clustered on a corm-like trunk ; aquatic or mud plants. 



Fam. 3. Isoetaceae. 



Family 1. LYCOPODIACEAE Michx. Club-moss Family. 



1. LYCOPODIUM L. Club-moss. 

 Sporanges borne in the axils of leaves, which are similar to those of the stem. 



