This section is from the book "A Guide To The Poisonous Plants And Weed Seeds Of Canada And The Northern United States", by Robert Boyd Thomson, H. B. Sifton. Also available from Amazon: A guide to the poisonous plants and weed seeds of Canada and the northern United States.
The Wild Black or Rum Cherry, Prunus serotina Ehrh., is a common tree extending from the east to the prairies. The danger from it lies in the presence of prussic acid in the wilted leaves. Animals may thus be poisoned by eating the leaves from broken branches. The toxic substance is also contained in the seeds. The symptoms and treatment for prussic acid poisoning are given under Sorghum where they may be consulted.
The tree is large, with reddish brown branches, and an aromatic inner bark. The latter is bitter, as in all the cherries, and is valuable for distinguishing their twigs from those of other trees, especially the birches. The leaves are oblong, thickish, shining above and taper-pointed, with incurved, short teeth. The small creamy-white flowers are in elongated racemes and the fruit is shiny, purplish black and has a pleasant taste.
*There are five of these in the Pasque Flower while in the Crocus proper there are six.
The Choke Cherry, Prunus virginiana L., is also dangerous in the same way as the Black Cherry, and has much the same distribution. It is a shrub or small tree with grayish bark, the inner layers of which have a disagreeable odour. The leaves are thin, abruptly pointed, sharply serrate with slender teeth, and the fruit is red, turning dark crimson, and very astringent. Willing, writing of conditions in Alberta, where the plant is often abundant and small, cautions against the use of hay containing recently wilted young shoots.
The Western Choke Cherry, Prunus demissa Walp., is a shrub or small tree with leaves thick and oval or obovate, more or less obtuse and with short teeth. The fruit is black and less astringent than that of P. virginiana. The toxic effects are similar.
The Wild Red or Pin Cherry, Prunus pennsylvanica L.. is a small tree growing from Newfoundland to the Rocky Mountains. It has light brown bark, leaves ovate or lanceolate, sharply and finely serrate, and small, bright red, sour fruit in corymbose clusters, like those of the cultivated cherry. Poisoning may take place as in other species of Prunus.
It is to be noted that the chief danger from all the cherries is from the wilted leaves. Care should be exercised to prevent stock from browsing on branches broken from trees, for example, after cherry-picking, or when haying, or droving cattle.
Fig. 11. - Wild Black Cherry - Prunus serotina.