182 GEOLOGY OF EASTERN WISCONSIN. 



which are very indicative of the nature of the marsh bottom on 

 which they grow, but which can scarcely be described in a manner 

 intelligible to the general reader, although they are readily distin- 

 guished by observing farmers. It may be remarked in general, how- 

 ever, that the better class consist of the grasses proper (Graminece), 

 not only because they are in themselves valuable, but also because 

 they indicate a bottom susceptible of easy improvement by the sub- 

 stitution of more valuable grasses. The Sedges (Cyperaceos) in gen- 

 eral occupy marshes that are of inferior value now, and are less 

 promising of immediate returns to labor spent in improvement. 

 Fortunately the former class largely predominate. 



CLASS XI. The Heath Group. This association of swamp vege- 

 tation is characterized by the predominance of the members of the 

 Heath family (Ericaceae). Among these the most characteristic 

 plant is the Leather Leaf (Cassandra calyculata), and the most im- 

 portant one is the Cranberry ( Vaccinium macrocarpon). The "Wil- 

 low, Larch and Sphagnum mosses and a variety of other plant's are 

 very frequent associates. This class is worthy of attention, not so 

 much in view of its prominence as a botanical group, as on account 

 of its present and prospective economic importance. The actual ex- 

 istence of the cranberry plant in its native state assures us of condi- 

 tions favorable to its growth and indicates where cultivation will be 

 most likely to prove remunerative. Where the cranberry itself is 

 not present, it is eminently desirable to know what plants are its ha- 

 bitual associates and demand similar conditions of soil and moisture, 

 since these may be almost equally good guides in the selection of a 

 suitable marsh for improvement. Of plants which serve this purpose 

 the Cassandra calyculata is regarded as the most reliable. On this 

 point an excellent work on the subject says: " In selecting a loca- 

 tion it is very important to observe the varieties of plants or trees 

 existing upon the ground. Although no cranberry vines may be 

 growing there, yet the presence of other plants requiring similar 

 conditions of soil and moisture indicate a soil congenial cothe growth 

 of the cranberry. For instance, the Feather-leaf, also called Gander- 

 bush and Leather-leaf (Cassandra calyculata\ so abundant in heath 

 ponds, is considered a sure indication of a proper locality." 



The distribution and additional facts relative to this group will be 

 given a few pages in advance. 



CLASS XII. The Tamarac Group. The name is perhaps a suffi- 

 cient definition even to the commonest observer. The Tarnarac or 

 American Larch (Larix Americana} constitutes the entire arboreal 



1 Cranberry Culture, by J. J. White. 



