EQUISETACE^. 



267 



Fig. 272. 



Fig. 273. 



the plant, broadly triangular, variously 

 decompound, with stalked divisions. 

 Fertile segment erect, 2-4-pinnate. Not 

 uncommon. 



18. OPHIOGLOS'SVM, L. ADDER'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. 



ORDER CXIII. EQUISETA'CEJE. 



(HORSETAIL FAMILY.) 

 The only genns of the Order is 



EQUISE'TOI, L. HORSETAIL. SCOUR- 

 ING RUSH. 



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 

 the Ferns, and reproduction is carried on in the 

 same manner ; but each spore of the Horsetail is furnished 

 with four minute tentacles which closely envelope it when 



Fig. 274. 



