CRYPTOGAMIA - EQUISETACE^E. 453 



HAB. Woods. Aug. Stem 2 10 feet long; branch, repeatedly 

 forked ; leaves small, pung. 



* * Spikes sessile ; leaves surrounding the stem. 



L. dendroideum: erect; branches alternate, crowded, dichotomous, 



erect ; leaves linear-lanceolate, in 6 equal rows ; spikes numerous, soli- 



tary, sessile. 

 HAB. Woods. July. About a span high; branch, numerous ; spikes 



3 4 on each plant. 

 L. rupestre : stem creeping, with ascending subdivided branches ; leaves 



scattered, imbricate, linear-lanceolate, ciliate, ending in hairs ; spikes 



solitary, sessile, quadrangular. 

 HAB. Rocks. July. Stem 2 3 in. long ; branch, numerous, some- 



what incurved ; plant grayish-green. 



* * * Spikes sessile ; leaves distichous. 



L. apodum : leaves 2-rowed, roundish-ovate, acute, denticulate, flat, acu- 

 minate ; spikes terminal, sessile, nearly soHtary, quadrangular. 



HAB. Wet rocky places. July. Resembling a moss, or Jungerman- 

 nia ; creeping. 



* * * * Fructification axillary. 



L. lucidulum : leaves in 8 rows, linear-lanceolate, denticulate, acute, 



spreadirig-reflexed ; stem ascending, bifid. 

 HAB. Woods. July. Stem 8 12 in. long, nearly erect, simp, or 



bifid, dark green. 



423. EQUISETUM. Horse-tail. 



E. hyemale : stem simple, erect, very rough, naked ; sheaths whitish, 



black at the base and summit. 

 HAB. Woods and marshes. April. StemV 3 feet high, slen., pale 



green ; spik. term., mostly solitary. 

 E. arvense : sterile stems decumbent, with simple branches, which are 



rough and quadrangular ; fertile stem erect, simple ; sheaths simple, 



cylindrical, incisely-dentate. 

 HAB. Boggy grounds. April. A span high ; sheaths of the fertile 



stems swelling ; teeth black. 

 E. sylvaticum : sterile and fertile stems with compound scabrous de- 



flexed branches. 

 HAB. Woods and low grounds. May. Branch, verticill. curved 



downwards ; sheaths loose. 



