ECOLOGY OF NORTHERN MICHIGAN. 89 



Bay, VIII, and Washington Harbor, I; and on the cliffs along the northwest 

 shore of the island. 



37. Populus tremuloides Michx. American Aspen. This tree occurs 

 in the same conditions as P. grandidentata but is more abundant. It was 

 abundant in the burnings and clearings at Siskowit Bay, VIII, and Washing- 

 ton Harbor, I. It also occurs on the rocky promontories at the southwest 

 end of the island, IX, on the cliffs along the northwest shore of the Isle, 

 and on the smaller islands in Lake Desor, VII. It prefers dry open 

 habitats and is one of the first trees to encroach on the clearings. 



38. Salix spp. Willow. Several undetermined willows occur in the 

 alder zone along the streams, II, IV, and about Lake Desor, VII. 



Betulaceae Agardh. Birch Family. 



39. Corylus rostrata Ait. Beaked Hazel-nut. As underbrush through 

 the forest, III, VI, with the Ground Hemlock. Often forming in small areas 

 a nearly pure stand. 



40. Betula papyrifera Marsh. Paper or Canoe Birch. Of general dis- 

 tribution, being a prominent form in the coniferous and deciduous forests, 

 although it predominates in neither. It is the chief deciduous tree on this 

 part of the island, owing to its general distribution. 



41. Betula lutea Michx. f. Yellow Birch. This birch is of general dis- 

 tribution in the forests of the slopes, VI, and river valleys, II, but is apparently 

 more abundant in the former. 



42. Alnus incana (L.) Willd. Speckled or Hoary Alder. Forms extensive 

 thickets along the streams, II, IV, about the shores of the Isle, and on low 

 ground around Lake Desor, VII. 



Santalaceae R. Br. Sandalwood Family. 



43. Comandra livida Richards. Recorded by Mr. Macduff as occurring 

 in an alder thicket near the mouth of Grace creek. 



Nyphaeaceae DC. Water Lily Family. 



44. Castalia odorata (Dryand) Woodv. and Wood. Sweet-scented White 

 Water Lily. In a small shallow bay at the west end of Lake Desor, VII. 

 The only place observed. 



Ranunculaceae Juss. Crowfoot Family. 



45. Caltha palustris L. Marsh-marigold. This species seemed to be 

 characteristic of the alder thickets, II, IV. ' 



46. Coptis trifolia (L.) Salisb. Gold-thread. Of general distribution 

 in the river valleys, II, IV, and V, and on the slopes, III and VI. 



Saxifragaceae Dumort. Saxifrage Family. 



47. Mitella nuda L. Occasional in the Tamarack and Spruce forests 

 along Washington river, II, and in the Balsam and Spruce forests of the 

 slopes, VI. 



Rosaceae B. Juss. Rose Family. 



48. " Opulaster opulifolius (L.) Kuntze. Eastern Ninebark. About the 

 shores of Siskowit Bay, VIII; on the Minong Trap promontory, IX, and 

 about the shores of the islands in Lake Desor, VII. 

 12 



