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NATURALIST'S GUIDE TO THE AMERICAS 



relief is in general verj^ moderate, the 

 highest point in the state, in the Porcu- 

 pine Mountains of Ontonagon County, 

 heing only 1421 ft. above the level 

 of Lake Superior. 



The two peninsulas of which the state 

 is composed are nearly surrounded by 

 the waters of the Great Lakes: Superior, 

 Michigan, Huron and Erie, giving a great 

 length of shore line. At many places 

 along these shores are developed exten- 

 sive sand dune areas. The presence of 

 the great lakes profoundly modifies the 

 climate of the state. The state is well 

 drained, with numerous rivers and small 

 streams. The drainage of Michigan is 

 all into the St. Lawrence River system, 

 with the possible exception of a few small 

 lakes in the western part of the upper 

 peninsula. 



II. FLORA 



The alternating tracts of clay, of sand, 

 and of gravel soil, and the varying fea- 

 tures of hill, bottomland, and of swamp, 

 marsh, or bog, due in general to the 

 effects of the former glaciers, result in 

 much overlapping of the various vegeta- 

 tion types in the state. 



Further, the state is, to a considerable 

 extent, the meeting place of the eastern 

 deciduous hardwood forest and of the 

 northern coniferous forest, and a con- 

 siderable part of the state is occupied 

 by the transition between these two 

 types of vegetation. 



On the uplands of Isle Royale in Lake 

 Superior and on the northern part of 

 Keewenaw Peninsula the Canadian 

 coniferous forest is dominant, the most 

 common trees being the balsam fir 

 {Abies balsamea), white spruce (Picea 

 canadensis), and paper birch (Betula 

 alba papyri/era). Isolated patches of 

 this type of forest occur south as far as 

 the northern part of the southern 

 peninsula. 



On the uplands with good soil in the 

 northern peninsula the dominant trees 

 are hard maple {Acer saccharum), yellow 

 birch {Betula lutea), and linden {Tilia 

 americana) . On lower ground with more 

 moisture the hemlock {Tsuga canaden- 



sis) becomes common in the hardwood 

 forest, and may on lower slopes form 

 pure stands. The white pine {Pinus 

 strobus) formerly occurred commonly as 

 large isolated trees in the hardwood 

 forest, and sometimes as a pure stand 

 covered considerable areas. 



In the central and eastern part of the 

 northern peninsula there are extensive 

 sand areas dominated by pines, mostly 

 jack pine {Pinus banksiana), though 

 much red pine .{Pinus resinosa) and some 

 white pine occurred. In general, the 

 pines seem to be successional stages 

 in the development of hardwood forest, 

 which is the climatic climax of the state, 

 and which when established prevents 

 the development of pine seedlings. The 

 jack pine grows on the poorest soil, 

 while white pine is a later stage requir- 

 ing quite rich soil, and red pine is inter- 

 mediate between these two in its require- 

 ments. On very sandy soil the hardwood 

 forest is extremely slow in replacing the 

 pines, which then persist for a long time. 



On protected wet slopes in this penin- 

 sula the arbor-vitae {Thuja occidentalis) 

 often formed extensive swamps, and 

 some of the trees reached a very large 

 size. In the lowlands there were very 

 extensive bogs covered by tamarack 

 {Larix laricina), black spruce {Picea 

 mariana), or arbor-vitae. Sphagnum 

 {Sphagnum spp.) and bog sedge {Carex 

 filiformis) are very characteristic of the 

 open parts of these bogs, and a number 

 of characteristic shrubs occur, such as 

 the leather-leaf {Chamaedaphne calycu- 

 lata), Labrador tea {Ledum groenlan- 

 dicum), and cranberry {Vaccinium 

 oxycoccus). 



The forests of the northern part of the 

 southern peninsula are quite similar to 

 those of the northern peninsula, except 

 that beech {Fagus americana) comes into 

 the hardwood forest as a prominent tree, 

 becoming more common to the south- 

 ward, while the yellow birch and hemlock 

 tend to drop out to the southward. 



In the southern peninsula, particularly 

 in the middle portion, there are very 

 extensive tracts of sand, originally 

 covered mostly by pines. However, 



