Northeastern Limits of the Known Range of Rhus 

 toxicodendron 



Robert T. Clausen 



lit 



Barkley (1937) indicated the northeastern Hmits of the dis- 

 tribution of Rhus toxicodendron, poison ivy, in North America 

 as Nova Scotia (Yarmouth County) and southern Quebec (Lon- 

 gueil) ; McNair (1925) as New Brunswick and Nova Scotia; 

 and Britton and Brown (1913) as Nova Scotia. In Gray's Manual, 

 there is no definite statement of range for the species. Barkley, the 

 monographer of the group, cited only one collection from Quebec, 

 and that from near Montreal. Marie- Victorin (1935) stated that 

 the species is general and very common in almost all habitats in 

 the middle portion of the St. Lawrence River basin, the area covered 

 by his flora. This statement is supported by a series of specimens 

 before me from various parts of this area : Ottawa, Aylmer, LTsle 

 de Montreal, Isle Perrot, Pointe-du-Lac, Grosse-Isle, Saint-Pie, 

 Montmorency Falls, and Berthier-en-Bas. From the extreme east- 

 ern border of this area, in the Matapedia River Basin, there are 

 specimens from Milnikek and from the junction of the Restigouche 

 and Matapedia Rivers. 



On the Gaspe Peninsula the species is apparently rare, but it 

 occurs out to the eastern extremity. On September 7, 1937, H. Tra- 

 pido and I, while botanizing along the eastern base of Mt. Ste. 

 Anne, encountered a large patch of the plant. Later, Prof. S. C. 

 Ball of Yale University sent me specimens (now in the herbarium 

 of Cornell University) of twigs and leaves collected by him on 

 September 6, 1939, from the top of a 400-foot talus slope below 

 the highest cliffs at St. Alban, Cap-des-Rosiers. Knowledge of these 

 occurrences led to investigation for further specimens from the 

 Gaspe Peninsula. At the Gray Herbarium are two such collections : 

 talus slopes, Cap-des-Rosiers, July 14, 1932, A. S. Pease; and 

 Riviere Petit-Pabos, on the flats about five miles above the mouth, 

 F. M .-Victorin, F. Rolland-G erniain, and E. Jacques, 44919. 



In Nova Scotia, poison ivy occurs eastward as far as Halifax, 

 Guysborough and Victoria Counties. Port Bevis, in the last-named 

 county, is the easternmost record known to me. 



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