B. P. I.— 326. 



MOUNTAIN LAUREL, A POISONOUS PLANT." 



By Albert C. Crawford, Pharmacologist, Poisonous-Plant Investigations. 



HISTORICAL INTRODUCTION". 



Many members of the Ericaceae, or heath family, contain principles 

 which are injurious to man and to animals. Of these the members 

 of the genus Kalmia especially interest us on account of their wide 

 distribution in the United States and from the fact that many cases 

 of poisoning in animals have been attributed to them. This genus is 

 American in origin, but is found mainly in the Eastern States; The 

 members of this group received their generic name in honor of Peter 

 Kalm, but their popular name, laurel, was given on account of the 

 resemblance of their leaves to those of the English laurel tree, a 

 member of an entirely different family.^ On account of the beauty 

 and perfection of their flowers they were once proposed as a national 

 emblem. 



Of these, mountain laurel (Kalmia latifolia), shown in Plate II, is 

 probably the most important. North of Maryland it is usually 

 known as mountain laurel, while south of Maryland it is sometimes 

 known as ivy.^ It has also received many other names, as calico 

 bush, e laurel/ sheep laurel, mountain ivy/ wintergreen, great laurel, 71 



a The mountain laurel, Kalmia latifolia L., has long been recognized by many 

 people as one of our most deadly shrubs. It is a poison fatal to live stock, es- 

 pecially to sheep and goats, which seem more likely than cattle and horses to 

 browse on it. The Bureau of Plant Industry is in receipt of letters inquiring 

 into the facts concerning its action and the methods of treating poisoned stock. 



Dr. Albert C. Crawford, Pharmacologist, under the direction of Dr. Rodney 

 H. True, Physiologist in Charge of the Poisonous-Plant Investigations of this 

 Bureau, has given, the matter laboratory study with the results here briefly 

 stated. — B. T. Galloway, Chief of Bureau. 



& Kalm, P. Travels into North America, 2d ed., vol. 1, p. 263, London, 1772. 



c Bailey, L. H. Cyclopedia of American Horticulture, 4th ed., vol. 3, p. 854, 

 1906. 



d Gronovius, J. F. Flora Virgin., pt. 2, p. 160, 1743. 



e Coulter, S. Catalogue of Flowering Plants * * * Indigenous to In- 

 diana. Dept. Geol. and Nat. Resources of Indiana, 24th Ann. Rept., 1899, p. 

 607. 



f Gronovius, J. F., 1. c, p. 160. 



s Smith, J. E. Natural History of the Rarer Lepidopterous Insects of 

 Georgia, vol. 1, pi. 73, 1797. 



ft Cutler, M. Account of Some of the Vegetable Productions Naturally 

 Growing in This Part of America. Amer. Acad. Arts and Sci. Mem., vol. 1, p. 

 442, 1785. 



121— n 21 



