EQUISETACE^. 



26T 



tho plant, broadly triangular, variously 

 decompound, witli stalked divisions. 

 Fertile segment erect, 2-4-pinnate. — Not 

 uncommon. 



18. OPHIOCiLOS'SOI, L. Addek's Tongue. 

 0. VUlga'tum, L. Sterile part of the 

 frond ovate or elliptical-oblong, 2-3 inches 

 long, rather fleshy, sessile, near the mid- 

 dle of the stalk ; the latter 6-12 inches 

 high. — Bogs and grassy meadows. 



Okder CXin. EQUISETA'CE.a:. 



(HoHSETAiL Family.) 

 The only geuns of the Order is 



EamsE'TlTM, L. Horsetail. Scodb- 



ING ECSH. 



Fig. 272 is a view of the fertile 



stem of Equise'tum arvense, the 



Common Horsetail, of about the 



natural size. It may be observed 



early in spring almost anywhere 



in moist sandy or gravelly soil. It 



is of a pale brown colour, and in place of leaves 



there is at each joint a sheath split into several 



teeth. At the summit of the stem is a sort of 



conical catkin, made up of a large number of 



six-sided bodies, each attached to the stem by 



a short pedicel. Each of these six-sided bodies 



turns out on examination to be made up of six 



or seven sporangia or spore-cases, which open 



down their inner margins to discharge their 



spores. Figs. 273 and 274 are enlarged outer 



and inner views of one of them. The spores 



themselves are of a similar nature to those of 



Fig. 272. ^jjg Ferns, and reproduction is carried on in the 



same manner ; but each spore of the Horsetail is furnishea 



with four minute tentacles which closely envelope it when 



