Toxicity in plants is often a matter of application and degree. Many plant medicines derive from deadly poisons, and many medicines are poisons if overused. Poisons also have their uses in the world.
Foxglove
Digitalis, foxglove, grows in many gardens. Its tall spikes of purple, rose, or white tubular flowers add drama and focus to many borders. The plant is also hardy, at least in central California, and as invasive as can be. It gave medicine one of the first cardiac remedies, slowing and strengthening the heartbeat and preventing atrial fibrillation. Digitalis has lengthened many lives, while enlivening the garden. One warning sign of digitalis poisoning, supposed to occur with ingestion of the minutest bit of plant matter, is a yellow-green tinge to the vision.
Buckeye
The Buckeye, Aesculus Californicus, is a tree or bush of almost magical beauty. It leafs out and flowers in early spring, the cone-shaped pink-tinged blossoms flooding the neighborhood with a delicate scent. It also is the first tree to drop its leaves in summer, baring twisted silver limbs to decorate the paths through California woodlands. It carries a poison so powerful that it is said to poison the honey of any bees that gather its nectar. Some tribes, the Zayante among them, used buckeye poison to catch fish, by powdering the large chestnut-like seeds and dropping them in pools. Stunned fish would float to the top of the water. In hard times, various tribes ate the buckeye itself, leaching out the poison first by soaking.
Belladonna
The Belladonna plant, Atropa belladonna, is known in the American west as Deadly Nightshade. It is a weedy looking plant with small black berries. Its poison, atropine, is actually gathered from many plants of this species. All are solanum, a group which also includes eggplants and potatoes. Atropine is still used to treat heart trouble, and sometimes in certain types of glaucoma. Cleopatra used it to dilate the pupils of her eyes, which was then believed to add allure. It was also used as an ordeal drug by several American tribes, though this atropine was generally derived from jimsonweed.
Chrysanthemum
Some chrysanthemums bear a useful poison. The variety Pyrethrum, Chrysanthemum cinerariaefolium, is the source of an effective natural insecticide, pyrethrin. This preparation poisons all insects, and in lower concentrations seems to repel mosquitoes and their many kin, but without doing much harm to mammal species. Pyrethrin does poison fish, but usually not birds. The poison is derived from the seed cases of the flowers. It biodegrades readily when exposed to sunlight.
Poppy
Opium, poppy latex, is a deadly and seductive poison, but has also been a friend and blessing for those with intractable pain. Produced from the immature seedpods of the Papaver somniferum, it is most often processed into morphine and heroin for the lucrative drug trade. Through generations, the poppy has been bred to produce ever more powerful latex, and the technology of drug production has also increased in deadly sophistication. At the same time, various synthetic opioids, such as percocet and fentanyl, whose effects are more standardized and predictable, have found a place in medicine. Morphine is still the standard for battlefield conditions, however. The poppy plant itself bears lovely flowers of red, orange, or white, and is grown in many gardens as an ornamental.
Poison exists in nature, but it is often created by the way a plant is used, rather than by the plant itself. The concentration of poppy juice and coca alkaloids converts these relatively benign substances to poisons, most useful only in illicit commerce. The gentle medicines we take from some plants may sometimes be more useful than the harsh chemical compounds brought to us by clinical science. Used thoughtlessly or to excess, either kind of compound may be poison.
