THE FERN ALLIES. 



37 



LITERATURE. 



BAKER (John G.). Fern Allies, pp. 7-123. London, 1887. 

 (George Bell & Sons.) 



SPRING (A.). Monographic de la Famille des Lycopodia- 

 cees. In Mtmoires de I 'Academic Roy ale de Belgique, XV, i-i 10 

 (1842); xxiv, 1-358 (1849). 



D. THE QUILLWORTS. 



99. Genera] Characters. The quillworts, so named 

 from the appearance of the 

 leaves, are principally incon- 

 spicuous aquatic plants of a 

 grass-like or rush-like aspect 

 (Fig. 27). Some species are 

 always submerged often in 

 several feet of water ; others 

 grow in marshy soil or in the 

 shallow margins of ponds or 

 streams, where they become ap- 

 parently terrestrial in time of 

 low water; while others still are 

 found between high and low 

 water marks, where they will be 

 covered by water at high tide. 

 The leaves are awl-shaped or 

 linear, and are attached to a 

 short fleshy trunk. They vary 

 in number from ten to one hun- 

 dred in each plant, and in length 

 from two to twenty inches in 

 various species. On account of 

 their resemblance to the im- 

 mature forms of rushes and 

 other aquatic vegetation of a 



higher order, they have been very sparingly collected. Many 

 questions of distribution, habits, and life-history may be studied 

 by even amateur botanists in various sections of the country. 



FIG. 27. Isoetes lacustris L., natural 

 size. (Redrawn from Sprague.) 



