MICHIGAN ACADEMY OF SCIENCE. 135 



Mesophytic Habitats. 



By far the largest part of this region is included here. But a short time 

 ago, comparatively speaking, LamlDton County was covered with an almost 

 impenetrable forest. At that time conditions were such that large quanti- 

 ties of water, received in the form of rain and snow, were retained for nearly 

 the whole summer season. The creeks and small rivers, more or less clogged 

 with rubbish, drained the wooded surface very slowly and the forests were 

 then known as "wet woods." Since that time a radical change has taken 

 place. At present the whole region is fairly well drained and most of the 

 timber has been cut; there are left here and there "wood lots" that partially 

 show the former conditions, although not very well as they are generally 

 heavily pastured. The Indian reservations below Sarnia and on the delta 

 islands, having undergone a less radical change, although parts are fairly 

 well cultivated, show better than any other localities what the original 

 vegetation was. From an examination of woods near Sarnia, Port Franks, 

 Rock Glen, Wyoming, Watford, Alvinston, and the Indian reservations, 

 especially on the delta islands (places covering the Avhole of the county), it 

 appears that, at least approximately, the original trees were in order of 

 abundance much as follows: American elm, black ash, red maple, basswood, 

 beech, sugar maple, ironwood (Ostrya virginiana), blue beech {Carpinus 

 caroUniana), silver maple, Crataegus punctata, red oak, bur oak, cottonwood, 

 yellow birch, shag-bark hickory, bitternut, sycamore, peach-leaved willow, 

 red ash, rock elm and slippery elm. Pin oak is the dominant tree on the 

 delta islands and here, or perhaps in parts of Kent County, reaches its north- 

 ern limit. The big shell-bark hickory, Carya laciniosa (Michx. f.) Loud., 

 comes as far north as Kent County and very probably exists on Walpole 

 Island. 



In such wet forests the species of plants in the undergrowth are not very 

 numerous. Among others were noticed the spice bush, moosewood, red- 

 berried elder, lizard's tail, jack-in-the-pulpit, wild leek (formerly very abun- 

 dant), wild garlic, groundnut (Panax trifolium), spikenard, wild sarsaparilla, 

 Circaea alpina, wood nettle, Cardamine douglassii, and Claytonia virgmica. 

 Much of the prairie-like land of the delta islands naturally falls within this 

 division. Hundreds of acres there are covered with Habenaria leucophaea, 

 Liatris spicata (a beautiful plant when in bloom), Indian grass, several 

 species of Panicum, vanilla grass, Gerardia paupercula, numerous sedges, and 

 Spartina Michauxiana. In spots are found Asclepias suUivantii, Tradescantia 

 reflexa, Viola sagittata, Vernonia illinoensis Gleason, Polygala incarnata, Pani- 

 cum virgatum, and Cypripedium candidum. 



Xerophytic Habitats. 



The beech and sand dunes at the foot of Lake Huron provide and illustrate 

 xerophytic conditions for plants. The beach has a very limited vegetation, 

 and many plants peculiar to itself and not equally distributed. Cakile 

 edentula is seldom abundant but fairly well distributed, prefers pure sand 

 and grows so near the water's edge as to be frequently washed bj^ waves. 

 Euphorbia polygdnifolia is abundant in spots and is often found in the drift- 

 ing sand of the beach. Artemisia caudata is frequent but this is also found 

 on the dunes. One plant of the beach, perhaps deserving particular notice, 

 is Circiuni pitcheri, a thistle known only along the Great Lakes, and named 

 for Dr. Zina Pitcher, an army physician stationed more than (50 years ago 



