Black locust is a shade-intolerant species and therefore is typical of young woodlands and disturbed areas where sunlight is plentiful and the soil is dry. In this sense, black locust can often grow as a weed tree. It also often spreads by underground shoots or suckers, which contributes to the weedy character of this species. Young trees are often spiny, but mature trees often lack spines. In the early summer black locust flowers; the flowers are large and appear in large, intensely fragrant clusters reminiscent of orange blossoms. The leaflets fold together in wet weather and at night (nyctinasty), as some change of position at night is a habit of the entire leguminous family.