BOTANIC, 

 OARDR^ 



The American Botanist 



VOL. XIII. JOLIET, ILL., JANUARY, 1908. No. 5 



LIPRAR' 



THE GENUS ACROSTICHUM. ^ew yoj 



BY WILLARD N. CLUTE. 



WHEN Thoreau wrote that nature "made ferns for pure 

 leaves, to show what she could do in that line" it is evi- 

 dent that he did not have a typical Acrostichitm in mind for of 

 all plants, the majority of this group are least like the convent- 

 ional idea of a fern. Beginners in the study may occasionally 

 press the leaves of yarrow, tansy and other plants with much 

 divided leaves under the impression that they are ferns, but 

 they rarely discover that the Acrostichums are such until they 

 have made considerable progress in naming the ferns. More 

 than two-thirds of the hundred and fifty species belonging to 

 this group have simple entire leaves that are more like the 

 leaves of plantain and dock than anything else. 



The author quoted, however, was nearer right than ap- 

 pears on the surface for nothing could better illustrate nature's 

 versatility than this fact that she has made a hundred differ- 

 ent species in a single genus by merely modifying the outline 

 of a simple leaf. In some species the leaves are broad, in 

 others narrow, some are long and others short, some rounded 

 at the apex and others pointed. The bases may be wedge- 

 shaped or rounded, or heart-shaped and the surfaces may be 

 scaly or smooth. By combining these various characters in 

 different groups the varied fomis have resulted. 



Many botanists are inclined to put all these simple 

 ^^ fronded ferns in a genus by themselves and to assert that no 

 ^S.^ species with divided fronds should be included in it. but the 

 "~ method of fruiting seems to bind together both the species 

 c«Q with simple fronds and those in which the fronds are divided. 



