MICHIGAN ACADEMY OF SCIENCE. 127 



The following plants are found here: (The first ten are the ones in Transeau's list). 



*Carex riparia, *.Juncus effusus, *Polygoniim sagittatum, *Typha latifolia,* Cornus stolonifera, 

 *Cornus candidissima, *Salix discolor, *Ulmu.s Americana. *Cephalantlius occidentalis, *Acer ruljrum 

 Scirpus atrovirens, Impatiens biflora, Polygonum 2 sp., Erechtites hieracifolia, Spathyema foetida, 

 Panicularia nervata, Osmunda regalis, Osmunda cinnamomea, Onoclea sensibilis, Dryopteris .3 sp., 

 Spirea salicifolia, Rosa Carolina, Naumbergia thyrsiflora, Riimex verticillatus, Koellia Virginiana, 

 Monarda fistulosa, Roripa Armoracia, Salix lucida, Salix petiolaris, Salix sericea, Salix 2 .sp.. Ilex 

 verticillata, Oxalis striata, Viburnum Lentago, Viburnum acerifolium, Sambucus Canadensis, 

 Prunus Virginiana, Prunus sp., Ribes t'loridum. 



The characteristic plants of this zone are the sedges and shrubs which are intermingled 

 except along the west end where the shrubs are lacking. Next to the open field there is 

 a much greater number of genera and species than anywhere else. Impatiens is abundant 

 at the shaded southwest corner and the polygonums at the more sunny north west comer. 



The intermediate zone is the main area of the bog and here are found : — 



Rhus Vernix, Vaccinium corymbosum, Acer saccharinum, Acer rubrum, Larix laricina, Aronia 

 arbutifolia, Ilicioides mucronata. Viburnum Lentago, Sambucus Canadensis, Rubus strigosus, Rubus 

 occidentalis, Populus grandidenlata, Populus tremuloides, Osmunda cinnamomea, Dryopteris 3 sp., 

 Unifolium canadense, Coptis trifolia, Sphagnum, Mosses, Typha latifolia, Solanum Dulcamara, Mono- 

 tropa uniflora, Naumbergia thyrsiflora 



Both red and black raspberries are found in open spaces where trees have been cut 

 out; but the red ones are frequent while the black ones are rare. On the hillside the re- 

 verse is true. In the dense shade of the larger maples and thick patches of Vaccinium 

 corymbosum the undergrowth of herbs is very scanty. 



The plants in the central region are 



Chamaedaphne calyculata, Sarracenia purpurea, Cypripedium acaule, Oxycoccus oxycoccus, 

 Vaccinium corymbosum. Sphagnum, Larix laricina, Carex trisperma, Rhus Vernix, Bidens sp., 

 Mosses. 



This seems to be the only place where the Sphagnum is really thriving. Carex trisperma 

 is very abundant here and is not found to any extent in any other place in the swamp. 

 Examination of the rings of wood on the stumps of half a dozen tamaracks showed an un- 

 usually slow growth between the years 1880 and 1890. 



The marginal zone and the central region have no plants in common and are separated 

 from each other by a region which has some of the plants from each and some from the 

 surrounding hillside together with others found in none of these places. 



These marked zones of vegetation and examination of the soil conditions show this bog 

 to be not at all a homogeneous habitat, but decidedly heterogeneous. 



Cattle are at times allowed free access to the swamp and have frequented the margin 

 at the west end more than anywhere else. They may have had much to do with keep- 

 ing the shrubs from getting a foothold here. Possibly they have had some influence in 

 aerating the margin — thus making it more like a drained swamp. 



Mac^NIillani describes the formation of plant atolls in lakes in Minnesota: Shaw- found a 

 marginal ditch around bogs near ^^'oods Hole due to falling leaves smothering out vege- 

 tation in that region ; and Atkinson^ suggests the same condition in New York may be due 

 to shading of the margin of the bog. It is not clear how this marginal region could have 

 originated in any of these ways. 



Da^^s* finds this marginal zone common in bogs in Michigan and believes it is caused 

 b}^ fluctuating water supply in this shallow part of the bog due to variation in annual rain- 

 fall and temperature. Then we would expect to find the marginal zone widest in the shal- 

 lowest part of the basin, but much to our surprise we found the widest part of the zone 

 deeper and wetter than any other part.. 



The west end of the swamp is deeper and has more water in the soil than the east end. 

 Here we find poison sumac and huckleberry thriving best while at the shallow east end 

 maples predominate and poplars are coming in, and the huckleberry bushes are dying out 

 in the dry coarse leaf mold in the shade of the maples. The tamarack is the only plant 

 of the central region which is still thriving in the rest of the swamp. 



Livingston's 5 detemiination of the osmotic pressure of bog waters shows that we can no 

 longer consider the presence of humous acid a physical cause for the xerophytic character 

 of the plants of the central region . A few preliminary thermometer readings seemed 

 to indicate that the soil is colder here than at the same depth in other parts of the bog. 



The distribution of the vegetation seems to have a definite relation to the height at 



iMacMillan, Conway. On the Occurrence of Sphagnum Atolls in Central Minnesota. — Minnesota 

 Botanical Studies. 1. No. 9, 1S94. 



2Shaw, C. H. The Development of Vegetation in the Morainal Depressions of the Vicinitj- of Woods 

 Hole. — Botanical Gazette, .June, 1902. 



^Atkinson, G. F. Lessons in Botanv. 



^Davis, C. A. An article vet unpublished. 



^Livingston, B. E. Physical Properties of Bog Waters.— Botanical Gazette, May, 1904. 



