MICHIGAN FLOKA. 429 



The influence of climate on vegetation may be summed up in a few words. 

 The climate of the Lower Peninsula is not as severe as that of the Upper, nor 

 so even, but is subject to frequent, sudden, and extreme changes of tempera- 

 ture — as great a variation during the winter season as 53° Fahr. in less than 24 

 hours having been recorded. Such rapid changes more or less affect vegetation, 

 especially the tender branches of cultivated trees, which are sometimes seriously 

 injured. In one or two instances a like effect on our forest trees has been 

 noticed. The annual range of temperature is about 11G°, and the annual 

 mean 46°. Of rain-fall, including what falls in form of snow, we have, yearly, 

 about thirty inches. Our snow-fall is much less, for the same latitude, than 

 that of New York and New England. In the center of the peninsula, we sel- 

 dom have more than a few inches at a time. 



The proximity of the Great Lakes exerts a marked influence in equalizing 

 the temperature and the effects are marked upon our flora. 



Trees like Liriodendron Tulip if era, Asimina triloba, Cercis Canadensis, 

 Gleditschia triacanthos, Comus florida, Nyssa multiflora, and Morus rubra, 

 which belong to Ohio and Central Illinois, have crept northward, favored by 

 the mild influence of the lake winds, through the central and western part of 

 the Lower Peninsula, often beyond the middle, and the same is true of smaller 

 and less noticeable plants. 



As might be expected from the uniform surface of the peninsula, the flora 

 is much alike throughout. Probably three-fourths of our species are common 

 to all sections, though by no means equally distributed ; some being very 

 abundant in one district and rare in another at no great distance. In most 

 cases such change is due to soil rather than to difference in elevation, tempera- 

 ture, or atmospheric moisture. 



The Lower Peninsula is covered with a deep drift of alternating sands, clays, 

 and gravels, and the flora of any section depends chiefly on which of these 

 happens to lie uppermost. With reference to its flora, the Peninsula may be 

 roughly divided into two great divisions — the hard-wood and the soft-wood 

 lands ; one representing the Appalachian flora, and the other, the Canadian. 



The hardwood country lies south of latitude 43°, and consists of very fertile 

 sand, clay, or loam, mostly cleared of the original forest, and largely culti- 

 vated. 



The sandy or stony drift of many river valleys in this section supports a 

 heavy growth of oak, frequently interspersed with walnut and hickory, while 

 the margins of the streams, and the neighboring swamps, abound in soft 

 maples, swamp and chestnut oak, white and black ash, elm, hackberry, syca- 

 more, butternut, and similar trees. Willows, dogwoods, viburnums, and but- 

 tonbush, are common shrubs in the swamps ; and hazel, hawthorn, wild 

 cherry and plum, June berry, witch-hazel, etc., are abundant on the dryer 

 ground. 



On the uplands, and away from streams, clay, loam, and a peculiar black- 

 muck soil, supersede the sands and gravels of the valleys. The prevailing 

 timber here is beech and maple and oak forest in about equal proportions. 

 Beech and maple {Acer saccharinum and var. nigrum) generally grow together, 

 forming magnificent forests of great extent. The best wheat farms are usually 

 found on uplands near streams, where the oak timber gradually shades into 

 beech and maple. Plains of fertile sand covered with a low, or scattering 

 growth of oak (oak openings) are frequent, and always very desirable for 

 farming purposes. Four species of oak are usually found on such plains — 

 Q. alba, macrocarpa, coccinea, and tinctoria. 



