Robinia pseudoacacia Semperflorens - Black locust

Robinia pseudoacacia 'Semperflorens' is a variety of black locust that is capable of re-flowering throughout the summer. Its highly fragrant flowering, in long clusters of cream-white flowers, is edible and honey-producing. A beautiful deciduous tree with fine foliage and a light crown, it provides dappled shade without harming the companion plants. This superb tree is also more wind-resistant than the species that only flowers in spring. A very attractive tree to plant as a specimen in a large garden!

The locust 'Semperflorens' was discovered in France around 1870. It is derived from the black locust Robinia pseudoacacia, a tree native to the eastern U.S.A. from the legume family. In this family, plants are capable of assimilating atmospheric nitrogen at their roots and therefore do not need to extract it from the soil; this characteristic allows them to grow in poor mediums.

The black locust 'Semperflorens' differs from the species by having slightly less vigorous growth, better wind resistance, and especially by its ability to produce several waves of flowers, even though the spring bloom is much more abundant. This medium to large tree, has a loose and initially upright habit, with a crown that flattens and becomes broadly ovate as it matures. Its growth is vigorous, reaching on average 20 m high and 15 m wide. Its branches are thin and reddish-brown, with few thorns. Flowering begins in May-June, on individuals around ten years old. Particularly generous, it will re-bloom in August-September, albeit in a more modest manner. It is not uncommon for the tree to flower continuously from June to September, in moist soil. The pendulous inflorescences measure 10 to 20 cm long. They consist of butterfly-like flowers that are cream-white. This very fragrant flowering with an orange scent attracts pollinating insects and can be used in fritters. It is followed by the formation of flat, reddish pods containing a few rare brown bean-shaped seeds. Note that only the flowers can be consumed; the rest of the plant is highly toxic.

This Robinia 'Semperflorens' should be planted as a specimen in a park or large garden. To enhance its appearance, plant it in front of a screen of conifers (cypress, thujas, yews, junipers) or evergreen trees. It can also be associated, in a flowering grove, with other low-maintenance and highly ornamental trees or bushes such as the acacia 'Casque Rouge', Albizia 'Rouge de Tuilière', and Melia azedarach 'Jade Snowflake'.