Tree Tobacco (not native)

Tree tobacco (Nicotiana glauca) is a small, open tree with rubbery, silvery-blue leaves and terminal clusters of tubular, yellow flowers. It blooms frequently along roadways, trails, abandoned fields and other disturbed areas.

Tree tobacco is native to South America. It was planted around the world as an ornamental garden plant and jumped the garden fence into the native wildlands of many countries. It is classified as invasive in California.

Although Native Americans are said to have consumed tree tobacco and to have smoked the leaves for ceremonial and spiritual purposes, smoking tree tobacco induces vomiting, and ingestion causes seizures and even death. Most authorities agree that it is unwise to ingest any part of this plant.

Description ^4,23,34,59

Tree tobacco is a small, open tree usually less than 20 feet (6 m) tall with arching or drooping branches. It is variously described as “spindly”⁴ and “straggling” ²³, and  “rangy”.⁴⁴⁴ The stems and leaves are blueish green, dusted with fine, waxy particles (glaucous). The leaves are generally oval in shape, shorter than eight inches (20 cm), and often with an acute or pointed tip. Petioles are somewhat shorter than the leaves. The leaf surface is smooth and rubbery to touch, and margins lack teeth.

Flowers occur in large, branched, terminal clusters that may contain blossoms and seed pods in all stages of development and in all seasons of the year. Flowers are symmetrical and bisexual. The calyx is five-lobed and persists around developing fruits. Five yellow petals are united into a long narrow tube, constricted before the mouth where the short lobes flare outward. Flowers are up to 1½ inches (4 cm) in length and are often tinged with green, especially near the mouth. There are five greenish-white stamens that do not project from the flower mouth; when open to shed pollen, the anthers resemble little mushroom caps. There is one pistil with a superior ovary and one style that holds the stigma just beyond the anthers – close to the flower mouth. The stigma is green with two lobes. The major bloom period is March – Sept.⁷ but flowers and seeds are found all year.

The fruit is a smooth, ovoid capsule, about a ½ inch (1.3 cm) long, surrounded by the brown calyx, which may be intact or split. The capsule splits from the tip, releasing numerous tiny brown seeds that are irregular in shape (mostly oval or D-shaped) and have a sculptured surface.

Classification ^2,44,143

Tree tobacco is a dicot angiosperm in the tobacco family (or nightshade family or potato family; Solanaceae). Members of this family have five petals that are fused into a tube, at least at the base. Sometimes the petals or lobes are reflexed. Fruits are either a berry or a capsule.  Many members of this family contain alkaloid compounds which may be toxic or narcotic; these include scopolamine, atropine, and nicotine.

Ecology ^443,445

Tree tobacco has the open structure and long, tubular flowers that favor hummingbirds over other pollinators, and in its native habitat, tree tobacco is strictly pollinated by hummingbirds. In California too, hummingbirds are the primary pollinator, with bees and other insects making rare visits, with occasional self-pollination. This specialization is unusual for a successful non-native invader, for which a broad range of potential pollinators in its new habitat broadens its chance of successful reproduction.

The pretty flowers of tree tobacco and their year-round production of copious nectar have made tree tobacco valuable as a garden ornamental, especially in bird gardens. On the other hand, there is some evidence that in the wild, the long and consistent period of nectar supply allows tree tobacco to out-compete native plants for hummingbird pollinators. In areas of the Santa Monica Mountains where tree tobacco “forests” are established, there are few if any native hummingbird-pollinated plants – plants such as California fuchsia (Epilobium californicum) and hummingbird sage (Salvia spathaceae) – even though these plants are abundant in nearby areas without tree tobacco. There is a brief mention of similar pollinator-competition between tree tobacco and prickly pear¹⁸³ and more direct evidence from a study of an invasive species of impatiens in Europe.⁴⁴⁶

Human Uses  

Like many plants in the nightshade family, tree tobacco contains alkaloids – primarily anabasine, chemically similar to nicotine. There are reports of tree tobacco used by native Americans in California both for medicinal purposes and for rituals, smoking, and consumption.²⁸² Locally, the Luiseño administered tree tobacco topically on wounds and as a fumigant to relieve earaches.¹⁷

It is also known that all parts of this plant are toxic, causing vomiting, hallucinations, respiratory failure, and death.^59,66 The California Poison Control System rates the toxicity as major.²⁰⁹ Most modern references warn against smoking or eating any part of the plant^11,15,66 – even the flower nectar.⁵⁹

In spite of its invasive tendencies, tree tobacco is often recommended for flower gardens, both for the long display of pretty yellow flowers and for the copious nectar which attracts hummingbirds.^441,445

Interesting Facts ²¹

Tree tobacco is in the genus Nicotiana, the name of which is clearly related to the chemical nicotine, present in plants of this genus. Both the chemical and the genus were named after a French diplomat and scholar, Jean Nicot de Villemain who is thought to have introduced tobacco to France about 1560. It was first introduced as a powder to inhale as a cure for headaches; it later evolved into snuff and became identified with the pleasure of nobility.

(The practice of smoking tobacco leaves began in the Americas over two thousand years ago and didn’t spread to Europe until the Spaniards arrived.⁵⁶)