ACROGEN^. 



11 



or economic point of view. They were formerly regarded as 

 slightly astringent, diuretic, and emmenagogiie, but are never 

 employed in medicine at the present day. The rhizomes contain 

 a good deal of starchy matters in the winter months, and might 

 therefore, in case of need, be used as food, like those of some 

 ferns. Silica is abundant in their epidermal tissues : this is 

 especially the case in Equisetum hyemale, Eough Horse-tail, 

 which is largely imported from Holland under the name of 

 Dutch Rushes, and employed by cabinet makers, ivory turners, 

 white smiths, &c., for smoothing the surface of their work. 



Natural Order 288. Marsileace^. — The Pepperwort Order 

 {fig. 1089). — Character. — Aquatic herbs with small floating or 

 creeping stems {fig. 1089), from which arise sessile {fig. 1089) 



Fig. 1089. 



Fig. 1089. The Creeping Pill-wort (Pilularia glohulifera). The stems are 

 creeping, and bear numerous sessile leaves, which are circinate in 

 vernation. The sporocarps are downy, and placed in the axils of the 

 leaves. 



or Stalked leaves {fig. 340). Leaves yfith. circinate vernation (j?^, 

 1089). Frtcctification at the bases of the leaves {fig. 1089), 

 and consisting of stalked valvular sporocarps {figs. 793, 796, 

 and 797) enclosing antheridia {fig. 794) and sporangia {fig. 

 795), which are either contained in the same cavity (fig. 793) 

 or in separate sacs {fig. 797). (See pages 363—365). 



Distribution, cfr. — They are widely distributed, but are most 

 abundant in temperate regions. Examples of the Genera: — 

 Pilularia, Marsilea. There are about 20 species. 



Properties and Uses. — Of little importance. Marsilea Ma- 

 cropus is known in Australia as the Nardoo plant. The sporo- 

 carps contain starchy matter ; these are pounded, and used as 

 flour. 



Natural Order 289. Lycopodiace^. — The Club-moss Order 



