excurrent

Excurrent is a botanical term describing a growth habit in which a plant or tree maintains a strong, dominant central leader—the main vertical stem—that continues to grow upward throughout its life. This results in a narrow, conical or pyramidal crown as mature individuals: branches are crowded toward the top and become sparser toward the base, creating an upright silhouette.

In many conifers, such as pines (Pinus), spruces (Picea), and firs (Abies), excurrent growth is common. The pattern keeps the lower branches from becoming heavily shaded and supports a tall, slender form that sheds snow more easily in snowy climates. Environmental factors, such as light availability and wind, can influence the degree of conicity, but the characteristic central leader is a defining feature.

By contrast, trees with a decurrent or broad-canopy habit exhibit more outward and downward branching, often yielding a wider crown with less emphasis on a single dominant trunk. The excurrent form is used in forestry, horticulture, and landscape design to describe architectural crown shapes and to aid in management decisions, such as pruning and growth prediction.

See also: crown shape, central leader, dendrology, growth habit.