Elderberries belong to the genus Sambucus, a group of fast-growing, woody-stemmed plants found across temperate and subtropical regions. The question of whether an elderberry is a tree or a shrub arises from its unique growth habit and potential to reach significant heights. Understanding the botanical classification of Sambucus requires examining the physical structure that distinguishes a shrub from a true tree.
Botanical Classification and Growth Habit
Elderberry plants are classified as deciduous, woody plants existing between a large shrub and a small tree. They are primarily considered shrubs due to their multi-stemmed nature, lacking a single, dominant trunk. Multiple woody stalks emerge directly from the root crown, which is typical of shrubs.
The growth pattern of Sambucus is characterized by quick, vigorous development and a tendency to spread by root suckers. This suckering habit encourages the formation of dense thickets or clumps. While the American elderberry (Sambucus canadensis) is often smaller (up to 10 feet tall), the European black elder (Sambucus nigra) can reach 20 feet or more, sometimes appearing tree-like. However, the multi-stemmed structure and short-lived individual canes differentiate the elderberry from a single-trunked tree.
Distinguishing Features for Identification
The leaves of the Sambucus genus are pinnately compound, meaning leaflets are arranged on either side of a central stalk. A typical elderberry leaf is composed of five to eleven leaflets, most commonly seven, each possessing sharply serrated edges.
In late spring to early summer, the plant produces abundant, fragrant flowers in large, flat-topped or slightly rounded clusters called cymes. These creamy-white to yellowish-white clusters can measure up to a foot in diameter. The woody stems and twigs feature a prominent white, soft pith in the center and distinct, corky spots called lenticels scattered along the surface.
Following flowering, the clusters develop into small, dark purple or black drupes, which are the mature berries. These berries ripen in dense, drooping bunches in late summer or early fall. While the berries and flowers are commonly utilized, the leaves, stems, and seeds contain compounds that can be toxic if consumed without proper preparation.
Native Habitats and Common Species
Elderberries have a wide geographic distribution, native to North America, Europe, and parts of Asia. They are highly adaptable but prefer environments that offer ample moisture, typically thriving along stream banks and at the edges of woodlands. They tolerate a range of soil types but grow best in rich, moist, and slightly acidic conditions.
The two most common species globally are the North American elderberry (Sambucus canadensis) and the European or Black elderberry (Sambucus nigra). Western North America is also home to the Blue elderberry (Sambucus caerulea), known for its distinct blue-black fruit.