Box elder trees (Acer negundo) are common across North America, recognized for their distinctive appearance among the maple family. Unlike most maples, they have compound leaves, with each leaf stem holding multiple smaller leaflets, often three to five, resembling ash trees. These adaptable trees grow rapidly and thrive in various environments, from river floodplains to disturbed urban areas. Their easily identifiable seeds play a significant role in the tree’s widespread presence and contribute to its reputation as a prolific seeder.
Identifying Box Elder Seeds
Box elder seeds are encased in a winged samara, a type of fruit. These samaras are typically light brown, measuring 2.5 to 5 centimeters (1 to 2 inches) long, and arranged in V-shaped pairs that hang in drooping clusters. Their V-shape allows them to spin like miniature propellers as they fall, earning them common nicknames like “helicopters” or “whirlybirds.” The small, dark brown, kidney-shaped seed is located at the base of the papery wing. Though seeds ripen from August to October, samaras often persist on the tree through winter, turning reddish-brown before eventually detaching, making them easy to spot even in colder months.
Box Elder Seed Dispersal
Box elder trees are prolific seed producers, their winged samaras designed for wind dispersal. The papery wing allows seeds to be carried considerable distances from the parent tree, contributing to widespread colonization. This efficient dispersal, combined with high seed viability, explains their common presence in various landscapes. Seeds ripen in autumn and fall continuously from the tree throughout winter and early spring. This extended shedding ensures wide distribution and increases the chances of successful germination. Their adaptability, abundant seed production, and wide dispersal allow them to quickly establish in disturbed sites.
Germinating Box Elder Seeds
To germinate box elder seeds, mimic their natural growth cycle. Collect seeds in the fall (September to October) once samaras mature and turn brown. Seeds require cold stratification (cold, moist conditions) to break dormancy, a process that naturally occurs over winter when seeds are planted in the fall. For indoor germination, stratify seeds by refrigerating them in a moist medium (e.g., peat moss, vermiculite) for 60 to 120 days at 0-5°C (32-41°F). After stratification, sow seeds gently on the soil surface or cover lightly with about 1 centimeter (3/8 inch) of soil. Maintain consistent moisture, avoid waterlogging, and provide at least four to six hours of direct sunlight daily for optimal growth.
Common Questions and Concerns
Box elder seeds are not considered edible for humans and may contain a toxin. However, the inner bark, young leaves, and sap (for syrup) are reported to be edible. While seeds are not typically allergenic, box elder pollen, released in late April and early May, commonly causes seasonal allergies, with symptoms like sneezing, runny nose, itchy eyes, and congestion. Prolific seeding and rapid growth can lead to abundant seedlings, which some gardeners consider a nuisance. Their weak wood makes them prone to limb breakage, especially in storms. Manage unwanted seedlings with manual weeding or mulch.