Tree tobacco (Nicotiana glauca) is a fast-growing plant that can shoot up to 10 feet tall in a single growing season. Hardy to U.S. Department of Agriculture plant hardiness zones 10 and 11, tree tobacco can be grown as an annual plant in colder USDA zones. Like other members of the nightshade family, all parts of the plant are toxic if eaten, with the poisonous compounds affecting not only dogs but humans, horses and cats as well.
The toxic effects of eating tree tobacco is caused by the alkaloid compound anabasine, which is related to nicotine. Unlike other members of the genus Nicotiana, tree tobacco doesn't usually contain nicotine but can occasionally produce it. Anabasine is more toxic than nicotine. If dogs eat vegetation of tree tobacco, anabasine causes symptoms including hyperexcitability, followed by more severe symptoms such as depression, vomiting, incoordination, paralysis and possibly even death of the animal, depending on the amount eaten.
According to the University of California, Davis, Veterinary Medicine website, pets rarely eat tree tobacco. It is more of a danger to grazing range animals such as cattle and sheep, where it can harm not only the animal that eats it but the developing fetus of a pregnant cow or sheep. If you suspect your dog has eaten tree tobacco, call your veterinarian immediately because by the time symptoms appear, it may be too late to successfully treat your pet.
Blue-green, 2- to 8-inch-long, somewhat succulent leaves cover the stems of tree tobacco plants. Tubular yellow flowers appear in nodding clusters at the ends of the branches in summer and fall. Hummingbirds pollinate the flowers, which produce abundant very small, black, dustlike seeds in round capsules. Each flower is open for about three days and produces nectar constantly during that time. Interestingly, even the nectar contains toxins, but the compounds don't seem to negatively affect the hummingbirds.
Tree tobacco is naturalized in the American Southwest and grows along roadsides, in waste places and fields. In some areas tree tobacco has moderately invasive capability. It can bloom almost year-long and furnishes nectar for migrating hummingbirds. Once you grow it, the minute seeds get dispersed by water and volunteer freely in pots and irrigated areas once the weather warms in the spring. Tree tobacco needs little care but is more attractive and grows more quickly with supplemental irrigation. Plants are used as hedges, barriers and additions to hummingbird gardens and low-water-use gardens. If your dog is an indiscriminate plant-muncher, do not grow tree tobacco where your pet can reach it.