The following species are less poisonous but have caused cases of poisoning in some form:— Lesser celandine (Ranunculus ficaria L.) ; bulbous buttercup (Ranun culus bulbosus L.) ; wood anemone (Anemone nemorosa L.) ; larkspur (Delphinium gayanum Wilmott) ; traveller's joy (Clematis vitalba L.) ; poppies (Papaver spp.) ; greater celandine (Chelidonium majus L.) ; charlock (Sinapis arvensis L.) ; soapwort (Saponaria officinalis L.) ; corn cockle (Agrostemma githago L.) ; St. John's wort (Hypericum perforatum L.) ; spindle tree (Euonymus europaeus L.) ; buckthorn (Rhamnus catharticus L.) ; yellow vetchling (Lathyrus aphaca L.) ; lupins (Lupinus spp.) ; broom (Cytisus scoparius Link.) ; fool's parsley (Aethusa Cynapium L.) ; water parsnip (Sium latifolium L.) ; chervils (Chaerophyllum spp.) ; scarlet pimpernel (Anagallis arvensis L.) ; privet (Ligustrum vulgare L.) ; black nightshade (Solanum nigrum L.) ; spurge laurel (Daphne Laureola L.) ; mezereon (Daphne mezer eum L.) ; caper spurge (Euphorbia lathyris L.) ; petty spurge (E. peplus L.) ; dwarf spurge ( E. exigua L.) ; sun spurge (E. helioscopia L.) ; box (Buxus sempervirens L.) ; darnel (Lolium temulentum L.) ; horsetails (Equisetum spp.). (H. C. L.) Poisonous Plants of North America.—Few plants indigen ous to North America are especially harmful to man. Especially noticeable are the species of Rhus known as "poison ivy" or "poison oak" and the species of Cicuta known as "water hemlock." Poison ivy produces a painful and sometimes serious dermatitis in susceptible persons and, as it is widely distributed, is perhaps the most important poisonous plant which directly affects man. The species of Cicuta are the most poisonous North American plants and have caused many deaths, especially of children, who, out of curiosity, eat the roots. There are many other plants, as, for example, species of the Solanaceae, which are distinctly poisonous, but do not ordinarily do much harm.
There is a large number of stock-poisoning plants, and the losses occasioned by them form a serious handicap to the stock raising industry. Some of these plants grow in the eastern part of the country and kill many animals there. It is in the West, however, that the greatest losses occur, owing to the frequent occurrence of these plants in that region and the methods of handling the animals. In the range country horses and cattle graze in large numbers without much supervision and their loca tion is changed frequently. The climatic conditions are not uni form and sometimes suitable forage is scarce. Some of the poison ous plants grow earlier than the grasses and other desirable forage. If sheep herders through ignorance close-herd their ani mals where poisonous plants grow freely, the resulting losses are sometimes very great. In some of the plants the effect only shows after prolonged feeding, and such cases are par ticularly exasperating, for symptoms may not appear until reme dial measures are almost useless.
Stock-poisoning Plants.—There are a few plants which are especially important and their effects may be briefly described. The water hemlock has already been mentioned ; the sum total of stock losses from this plant is not large, but it is as fatal to animals as to men, and when eaten will usually produce death.
The species of death camas (Zygadenus), while affecting cattle and horses, are especially destructive of sheep, these losses occur ring mostly in the spring. Losses of hundreds of sheep in a band occur rather frequently. The lupines rank second to death camas as sheep-poisoning plants. While lupine leaves are generally harmless, the fruit is distinctly poisonous and produces many losses in the late summer and fall. The larkspurs are especially destructive to cattle, and the majority of cattle losses from poisonous plants in the mountain regions are caused by these plants. Under range conditions sheep and horses are not poisoned by the larkspurs. The larkspurs grow in great profusion in the mountain regions of the West and it is there that most of the lark spur losses occur, although there are deaths in the Eastern States and on the Great Plains.
Poisoning by cockleburs, species of Xanthium, has for many years been reported as probable, and recent investigations have shown that the losses caused by this plant are quite heavy. The poisoning results from eating the young plant in the cotyledon stage when the first leaves are forming. Animals do not eat the mature plant. All classes of stock may be affected by the cockle bur, but the losses are mainly of cattle and swine. The plants are very widely distributed.
There are several species of milkweeds that have been proved to be the cause of large losses of sheep. These losses have occurred mostly in the Rocky mountains and in the States west to the Pacific coast.
There is a very interesting poisonous plant found in south western Texas, Mexico, and Lower California, known as coyotillo (Karwinskia hurnboldtiana). This does not produce acute symp toms, but from a single feeding, after a lapse of some days or even weeks, paralytic symptoms appear which gradually increase until the animal becomes helpless. The condition is practically permanent with slight chance of recovery. This plant may affect all classes of live stock, the principal losses being of sheep and goats.
Loco Weeds.—Probably, in the aggregate of losses, the loco weeds, species of Astragalus and Oxytropis, have been the most destructive of all North American plants. They are found widely distributed in the semi-arid Great Plains region east of the Rocky mountains from northern Canada into Mexico, and in lesser quantities farther west. The word loco is from the Spanish, meaning crazy, and the prominent symptoms produced by the true loco weeds are those of a disordered nervous system. Many animals get a "loco habit" and will eat nothing else; a "locoed" horse cannot be led or backed, shows marked loss of muscular co-ordination, becomes unmanageable and is dangerous to use. A chronic "loco eater" gradually loses all appetite, grows weaker and dies. The losses of horses, cattle and sheep from these plants have been enormous, but are gradually growing less, as much of the former range country is taken up by farmers, and as the increased value of live stock has brought about more careful supervision of the animals.