MICHIGAN ACADEMY OF SCIENCE. 
219 
interior the red oak, beech and sugar maple are often abundant and 
intermingled and in places tin* balsam, white spruce, and white cedar are 
abundant and usually associated. A large area of yellow birch stands 
by itself on high ground toward the east side. Canoe birch is scattering, 
and the white pine and red pine are not prominent. 
Over 400 species have been noticed on the island and it is not probable 
that more than 100 species more grow there. Of the 415 reported in the 
present paper at least GO are introduced plants, usually known as weeds, 
leaving 355 observed native species, so it appears that 450 is probably a 
close approximation of the number of native species and varieties on 
the island. 
A C K X OWLEDG M EX TS. 
I am much indebted to Agnes Chase, Scientific Assistant in Systematic 
Agrostology, Bureau of Plant Industry, U. S. Department of Agricul- 
ture, for examining the various species of grasses, and to Kenneth 
Mackenzie, of New York City, for inspecting all species of Cyperaceae, 
Junci, and many other plants. 
LIST OF SPECIES. 
POLYPODI ACEAE FERN FAMILY. 
Phegopteris dryopteris (L.) Fee. Oak Fern. Plentiful in rich shaded 
ground. 
Adiantum pedatum L. Maidenhair. Often abundant in rich shaded 
ground. 
Pteris aquilina L. Common Brake. Occasional in shaded or open 
ground. 
Asplenhim filix-femina (L.) Bernh. Lady Fern. Frequent in rich 
shaded ground. 
Aspidium thelypteris ( L.) S\v. Marsh Shield Fern. Common in damp 
shaded or open ground. 
Aspidium marginale (L.) Sw. Evergreen Wood Fern. In rich shaded 
ground apparently rare. 
Aspidium spinulosum (O. F. Muller) Sw. Spinulose Shield Fern. Occa- 
sional in shaded ground. 
Aspidium spinulosum intermedium (Mulil.) 1). C. Eaton. Spinulose 
Shield Fern. Frequent in rich shaded ground. 
Cystopteris bulbifera (L.) Bernh. Bulblet cystopteris. Abundant on 
rocky shaded ground. 
Onoclea sensibilis L. Sensitive Fern. In damp open or shaded ground. 
OP II I OG LOSS ACEAE ADDER'S TONGUE FAMILY. 
Botrychium virginianum (L.) Sw. Kattlesnake Fern. Common in rich 
shaded ground. 
EQUISETACEAE HORSETAIL FA M ILY. 
Equisetum arvense L. Common Horsetail. Frequent on the sandy 
beach and in damp open or shaded ground. 
