NATIVE WOODY PLANTS OF THE UNITED STATES Q 



POISONOUS PLANTS 



Plants dermatitically poisonous to man ordinarily will not be 

 planted, because collection of seed or cuttings cannot be made with- 

 out exposure to the irritants. In many places such plants may be 

 spontaneous. If they are of value in erosion control or as wildlife 

 food or cover and particularly if they are sufficiently removed from 

 habitations, they may often be left to perform a useful function. 



The subject of livestock poisoning has been admirably treated by 

 Chesnut and Wilcox (119) and by Marsh ($98). Their authoritative 

 generalizations are paraphrased here. 



It may be stated as a general fact that the popular idea that range 

 animals will voluntarily seek out poisonous plants and eat them from 

 preference is not true. Animals seldom eat poisonous plants except 

 as they are driven to do so by lack of other food. Almost all poison- 

 ous plants are distasteful to livestock and under ordinary circum- 

 stances will be avoided. Loco plants, which are herbaceous, are an 

 exception to this rule. 



The state of the local vegetation as affected by weather conditions 

 ordinarily exercises considerable influence on the occurrence or non- 

 occurrence of poisoning. In the early spring certain poisonous plants 

 may start to grow before the native grasses. If these poisonous 

 plants are at all conspicuous or offer any considerable amount of 

 succulent material, livestock may be tempted to eat them. The acrid, 

 bitter, or otherwise disagreeable taste of such plants seems not to 

 deter livestock. Sheep and cattle may often eat large quantities of 

 plants that are extremely distasteful to the human palate. 



In seasons of unusual drought, grasses on the range may become 

 thoroughly dry while other plants remain green and tempting. It 

 is obvious that livestock will be more apt to eat poisonous plants 

 when such plants offer more tempting forage than the grasses. It 

 is equally obvious that when grasses and other harmless forage plants 

 are present in abundance and in good condition, sheep and cattle less 

 often make the mistake of eating poisonous plants. 



To prevent poisoning of livestock, reliance should be placed on 

 prevention rather than remedies. Animals must be so well cared for 

 that they will not be tempted to eat poisonous plants. They must be 

 prevented from eating such plants by careful handling of the herds. 

 It must always be borne in mind that animals seldom eat poisonous 

 plants by preference, but that under starvation conditions they may 

 be driven to do so with disastrous results. 



Usually, in selecting stock for planting, nontoxic species can be 

 chosen. In rare instances, however, certain toxic forms may be the 

 only ones capable of doing the job. In such event, great care should 

 be exercised to see that plantings will not be available to livestock. 

 This can be accomplished either by fencing or by proper management 

 of the herd. 



AGGRESSIVE PLANTS 



Whether to include or exclude a species that may become a pest 

 is often a difficult decision to make. Extreme aggressiveness may be 

 the character necessary for successfully controlling a given site, but 

 if such aggressive species spread and become a nuisance because they 

 are difficult to eradicate, the planter may often regret having used 

 them. 



