I have always had a love/hate relationship with trees of the legume family. Legumes are plants which have the ability to fix nitrogen from the air. Peas and beans are the best-known examples of a legume but there are many.
There are some excellent trees in the legume family and I’ll expand on their many virtues later in this column. Without exception they’re tough, drought-tolerant, disease and pest resistant and very well-adapted to Okanagan growing conditions.
But they can be a hard sell in the retail garden centre for the simple reason that they don’t have those beautiful classic shade tree canopies as a young specimen. Maples, dogwoods, birch, hawthorns look like miniature versions of their mature selves in a seven or a ten gallon container. Legume trees of a similar size could be best described as “gangling,” like a teenager whose co-ordination hasn’t caught up with their most recent growth spurt.
If you can look past the adolescent awkwardness and envision the tree as a mature adult you’ll find some wonderful choices for Okanagan gardens. Here are some of my favourites:
Koelreuteria paniculata (Golden Rain Tree)-This tree is covered with large clusters of golden yellow flowers in July and August, and then they fall and cover the ground like a golden rain shower. In fall seed pods form which look like tiny Japanese lanterns, rattling gently in the wind throughout the winter. An exquisite tree that matures at about 25-30 feet.
Robinia pseudoacacia 'Purple Robe'-The Black Locust has a bad reputation as a weed tree. True, the species does find its way around due to its ability to self-seed and grow almost anywhere. But look closely at them. Mature trees have incredible deeply furrowed bark and when the white clusters of blooms appear in May entire neighbourhoods bask in the fragrance. ‘Purple Robe’ is less aggressive, with fewer seed pods than the species and more compact growing (about 40 feet). Its blooms are purple, hanging in clusters like those of the wisteria.
Cercis canadensis (Eastern Redbud)-Any tree that flowers from bare wood before the leaves emerge is special. The redbud creates a haze of rosy purple blooms in April and then the heart-shaped foliage emerges to complete the scene. The cultivar ‘Forest Pansy’ has deep purple foliage which lightens somewhat in the summer heat. This tree is slow growing to about 25 feet high and wide.
Gleditsia triacanthos (Honey Locust)-It may be a common tree in many areas, but it grows so well, with few problems and casts such a lovely, light shade on a hot summer afternoon. ‘Sunburst’ is by far the favourite cultivar. Its new foliage emerges yellow before maturing to a light green. It matures at 30 to 35 feet high with a broadly pyramidal canopy.
Sophora japonica (Japanese Pagoda Tree)-Rarely seen in landscapes, but a beautiful tree that features creamy white blooms in July and August and small leaves that produce a nice dappled shade. Sophora is adaptable to most growing locations; in Summerland there is a thriving specimen in the parking lot on the south side of the municipal building where temperatures likely hit 40 deg. C in mid-summer.
