2728 



POISON BERRY 



POISONOUS PLANTS 



POISON BERRY: Oestrum. P. Dogwood: Rhiis vernix. P. 

 Elder: Rhiis venenata. P. Hemlock: Conium maculatum. P. Ivy: 

 Rhus Toxicodendron. P. Oak: Rhus Toxicodendron. P. Sumac: 

 Rhus vermix. 



POISONOUS PLANTS. The plants that are 

 injurious to man and the domestic animals may be 

 divided into two groups: (1) those that cause injury by 

 mechanical means; and (2) those that are poisonous. 



3088. Leaf of poison ivy. ( X 1 A) 



The first group includes those plants which are mainly 

 harmful to farm cattle, causing serious troubles which 

 may result eventually in the death of the animal. This 

 group includes such plants as the crimson clover, 

 Trifolium incarnatum, spiny cacti (Opuntia) , the hairs 

 and spines of which form the hair- and spine-balls known 

 as phyto-bezoars. The branched hairs of the calyx of 

 the crimson clover, if eaten by horses and cattle, when 

 in full flower, are rolled together to form the hair- 

 balls which have been responsible for the death of many 

 animals. The spines of species of Opuntia in Mexico and 

 the southwestern United States cause the laceration of 

 the mouth and tongue of cattle and death has resulted 

 in a number of cases, where these spines have been rolled 

 into phyto-bezoars. ^Egagropilae are balls formed from 

 animal hairs which have been licked off and swallowed. 

 Through the peristaltic movement of the intestines 

 these have been rolled into balls. The silex in the stems 

 of the scouring-rushes (Equisetum) is responsible for 

 inflammation of the digestive organs of cattle. 

 The hygrometric structures attached to the 

 fruits of such grasses as Stipa capillata (Rus- 

 sia), S. spartea (United States), Aristida 

 hygrometrica (Queensland), and Heteropogon 

 contortus (New Caledonia), by their spiral 

 movements cause the pointed ends of the 

 fruits to bore into the skin and flesh of ani- 

 mals in those regions of the earth. The 

 blue-mold, Aspergillus fumigatus, which lives 

 at blood temperature, penetrates the lung 

 tissues of calves and pigeons, and its masses of 

 spores fill up the air-cavities and lung-pas- 

 sages, causing asphyxiation. These are some 

 of the illustrations of plants that kill, or cause 

 injury, by mechanical means. 



The poisonous plants, however, are those that con- 

 tain some chemical poison which either produces 

 irritation, disease, or death by its direct action. The 

 season of the year has a direct influence on the activity 

 of a poisonous plant. Melter (1899) records that his 

 horse ate 500 pounds of the dried hay of Passiflora 

 incarnata in August without injury, while in March, 

 eight months later, 25 pounds of the hay of this plant 



killed another horse. The condition or age of the plant 

 is important. The poisonous principle in the spotted 

 hemlock, Conium maculatum, is volatile, and hence the 

 dried plant is less poisonous than the fresh. The leaves 

 of wild black cherry, Prunus serotina, are more poison- 

 ous when dry than when fresh, owing to the develop- 

 ment of hydrocyanic acid. Some parts of a plant are 

 more poisonous than others. For example, the seeds of 

 the Jamestown weed, Datura Stramonium, are more 

 deadly than the remainder of the plant. Again it may 

 be said that the relative amounts of poisonous sub- 

 stance vary in different individuals of the same species 

 and that small doses of some poisons are taken with 

 beneficial results, for instance the use in medicine of 

 belladonna, strychnine, and aconite. The toxic proper- 

 ties of plants are not due in all cases to the same chemi- 

 cal substance. It is well known that several plants con- 

 tain a number of toxic bodies. For example, the green 

 hellebore, Veratrum viride, contains the alkaloids 

 jeryin, cevadin, and veratrin. Sometimes the same 

 poison is present in more than one species, as solanin 

 in the tomato and the potato. Not all animals are 

 equally affected by the same poison, as for example, the 

 darnel which poisons men, dogs, horses, and sheep, 

 but is innocuous to cows, pigs, and ducks. Some per- 

 sons are susceptible to poison ivy, others are not. This 

 susceptibilty may be increased by sickness, or a run- 

 down condition. Some animals acquire a craving for 

 certain injurious plants, as for example, the loco weeds 

 of the United States, stemless loco weed, Oxytropis 

 Lambertii, and in Australia, according to Maiden, the 

 indigo plant, Swainsona galegifolia. Kobert divides 

 poisonous plants into three groups: (1) irritants which 

 cause gross anatomic changes, as crotqn-oil; (2) blood 

 poisons, as ricin; (3) poisons which kill without ana- 

 tomic changes, as morphin, digitalin, and the like; and 

 a fourth class may be added, (4) skin-irritants, as poison 

 ivy. 



The most poisonous lower plants are fungi belonging 

 to the genus Amanita. The two most virulent are the 

 toadstools, Amanita muscaria, which contains muscarin, 

 and A . phalloides with phallin. Fortunately, an antidote 

 has been discovered for the first in the administration of 

 hypodermic injections of atropin beginning with 1-100 

 of a grain, and increasing the dose to a strength of 

 1-60 of a grain. For phallin, no antidote is known. Of 

 the higher plants, the most noted poisonous ones are: 

 Aconitum Napellus (monkshood); Delphinium Geyeri 

 (larkspur); Oxytropis Lambertii and Astragalus mol- 

 lissimus (loco weeds); Rhus radicans (poison ivy), 

 which is a serious skin-irritant; Rhus vernix (poison 



3089. Poison sumac. Rhus vernix. ( X 14) 



sumac), which is also decidedly toxic to the skin; 



Cicuta maculata (cowbane), which contains two poisons 



conin and cicutoxin; Conium maculatum, the classic 

 poisonous plant, from which came the death-draught 

 of the philosopher Socrates; Kalmia latifolia and A". 

 angustifolia, the two poisonous laurels; Datura Stra- 

 monium (Jamestown weed); Atropa Belladonna (deadly 

 nightshade) and others too numerous to mention. 



Popular interest usually attaches to the poison ivy, 

 Rhus radicans or R. Toxicodendron (Fig. 3088), a root- 

 climbing vine with ternate leaves, and the poison 



