Erfdsetum.'] CRYPTOGAMIA — EOUISETACETE. 393 



CRYPTOGAiMIA— EQUISETACE.E. 



1. Equisetum. Linn. Horse-tail. 

 * Fertile stems unhranclied, succulent, appearing before the sterile 

 o?ies which have lohorled branches. 



1. El. Jluvidtile, L. {great Water Horse-tail); sterile stems with 

 very numerous (about 30)striteand nearly erect simple branches, 

 stem cylindrical smoothish, sheaths with close small subulate 

 teeth, fertile stems (short) without branches clothed with ample 

 loose sheaths having many subulate teeth, E. Bot. t. 2022. 



Muddy lakes, sides of rivers and pools, frequent. Fr. Apr. — The 

 largest of all our species, its sterile stems or fronds being 3—4 feet 

 high. 



2. E. Drummondii, {blunt-topped Horse-tail); frond very ob- 

 tuse at the extremity, sterile stem especially upwards scabrous 

 with prominent points and about 20 strise, teeth of the sheath 

 appressed, branches simple patent, fertile stem without branches 

 its sheaths approximate appressed with subulate teeth. Hooh. 

 Br. Fl. ed. 1, and in E. Bot. Suppl. t. 2777. 



Scotland, rare ; banks of the Isia and Esk, in Forfarshire, extending 

 up the vallies to their sources ; Mr T. Brummond. Near Forfar and 

 by the Caledonian Canal, Dr Graham. Near Belfast, Mr Harvey. Fr. 

 Apr. — Allied to the following species, but unquestionably distinct. Its 

 colour is greener and less glaucous, its stems rougher, with closely set, 

 raised points, its angles and branches much more numerous, and the 

 whole barren frond is singularly blunt (in its outline) at the extremity, 

 by which it may at once be known from E. arvense. The sheaths, 

 though paler at the base, have blacker and more prominent ribs upwards, 

 and they are so close as to imbricate each other : their teeth also are 

 more numerous when they separate into the proper number. 



3. E. arvense, L. {Corn Horse-tail); frond attenuated up- 

 wards, sterile stem slightly scabrous with 12 — 14 furrows, 

 teeth of the sheath lanceolato-subulate, branches simple erecto- 

 patent, fertile stem without branches its sheaths remote loose. 

 E. Bot. t. 2020. 



Corn-fields and road-sides, frequent. Fr. Apr. ; afterwards the 

 sterile stems appear. 



** Fertile stems similar to the sterile ones, simple or branched. 



4. E. sylvdticum, L. (branched Wood Horse-tail); sterile and 

 fertile stems with about 12 furrows, branches compound whorl- 

 ed deflexed, sheaths lax with ab(mt 6 or 12 long membrana- 

 ceous obtuse teeth. E. Bot. t. 1674. 



Moist woods, hedge-banks ; abundant in the north. Fr. Apr. May. 

 — A graceful species, less rigid and more herbaceous than any of the 

 following. Sterile plants pyramidal in their outline ; fertile ones abrupt 

 at the top, especially after the fructification has passed away. 



5. E. limosum, L. (smooth naked Horse-tail); stem smooth 

 striated, striae about 16-^18, teeth of the sheaths short rigid 



