Western waterhemlock, also called cowbane, poisonhemlock, and poisonpars- 

 nip, is an extremely dangerous, poisonous plant of the carrot or parsnip family 

 ( Umbel liferae). It is a coarse, perennial marsh herb, which has a characteristic 

 short, nearly erect, root crown, partitioned within, and bearing a cluster of 

 elongated, coarse, fleshy roots. The stout, erect stem is 2% to 6 feet high. 



Western waterhemlock is the commonest and most widespread of the western 

 species of waterhemlock, and ranges from South Dakota to New Mexico, Cali- 

 fornia, British Columbia, and Alaska. South Dakota marks the eastern limit 

 of western waterhemlock and, at the same time, the western limit of spotted 

 waterhemlock (C. macula'ta), a more slender, essentially eastern species. In 

 some of the important reference literature on range plants, C. maculata and 

 C. ocddentalis are not distinguished. Western waterhemlock is a moisture- 

 loving plant, and commonly grows in marshes, swamps, wet meadows, along 

 streams, irrigation ditches, and similar places. It occurs in the plains, foothills, 

 and mountains up to elevations of about 9,000 feet. Ordinarily the plants have 

 a scattered distribution, although in certain restricted areas they may be found 

 growing in dense stands. 



This plant, as well as other species of Cicuta, has not only killed large 

 numbers of livestock, especially cattle and sheep, but has also resulted in 

 fatalities among human beings. The root crown and other underground por- 

 tions of the plant are the most poisonous parts. A small piece of root, 

 which may easily be pulled up by a grazing animal, especially in the spring, 

 is sufficient to cause sudden and violent death, the older root parts being 

 the most toxic. The stems and leaves of the young shoots may poison livestock 

 early in the season, but are not so dangerous in the summer and autumn. 

 The dried seeds and older tops probably are not a source of danger. 1 



The high percentage of fatalities in western waterhemlock-poisoning cases 

 indicates the need for efficient prevention. Livestock should be protected from 

 the danger of eating waterhemlock by appropriate measures herding, fencing, 

 grubbing, etc., as the individual case may indicate. If the area of infestation 

 is not too extensive, the most practical control is to eradicate the plants by 

 grubbing. The plants thus removed should be burned as soon as possible before 

 livestock have access to them. 2 The restricted habitat and ordinary relative 

 scarcity of the plants in a given location facilitate this manual method of 

 extermination. It is especially desirable to eliminate waterhemlock from the 

 vicinity of water holes where livestock congregate regularly and are liable 

 to eat the plant It is often reported, although definite proof is lacking, that 

 death has resulted from the contamination of water by the hoof-bruised roots 

 of the western waterhemlock. 



Both root crown and roots have a strong, disagreeable, musky odor, and 

 when broken exude an acrid, yellowish fluid, which contains the poisonous 

 principle. 



Tuber waterhemlock (C. vdgans), a species very closely related to western 

 waterhemlock and sometimes called Oregon waterhemlock, has a more re- 

 stricted range, occurring from British Columbia to Montana and south into 

 northern California and central Idaho. It also occupies marshes and oth-er wet 

 places, mostly within the ponderosa pine belt, is virulently poisonous, and is 

 the species of waterhemlock most frequently illustrated in the various publica- 

 tions concerning poisonous range plants. Its herbage has a bluish or purplish 

 tinge, the stems are branched from the base, and are weaker than those of 

 western waterhemlock; its large fleshy rootstocks (rhizomes) are horizontal 

 and often occur partly above ground. The small, ribbed "seeds" of this species 

 are rounded as contrasted with the more nearly egg-shaped or ellipsoidal fruits 

 of the western waterhemlock. 



1 Marsh, C. D. STOCK-POISONING PLANTS OP THE RANGE. U. S. Dept. Agr. Bull. 1245, 

 rev., 75 pp., illus. 1929. Supersedes Bull. 575. See also Marsh, C. D., Clawson, A. B., 

 and Marsn, H. CICUTA, OR WATER HEMLOCK. U. S. Dcpt. Agr. Bull. 69, 27 pp., illus. 

 1914. 



2 Fleming, C. E., Peterson, N. F., Miller, M. R., Wright, L. H., and Louck, R. C. THE 



POISON PARSNIP OF WATER HEMLOCK (CICUTA OCCIDENTALISM A PLANT DEADLY TO LIVESTOCK 



IN NEVADA. Nev. Agr. Expt. Sta. Bull. 100, 23 pp., illus. 1920. 



