The Protea Family is a remarkable group of plants mostly native to the southern hemisphere, with concentrations of species in South Africa and Australia.
Examples from South Africa include Protea and Leucospermum, both with intricately constructed flower heads, which are popular as cut flowers. Australia has by far the most species, however, many of them found in the genera Grevillea, Banksia and Hakea, with each encompassing well over 100 species.
Of these Australian groups, the genus Grevillea is the best known in horticulture, with hundreds of hybrids as well as species available in the nursery trade. Although they have not been hybridized or popularized as extensively, Banksia and Hakea are also notable for their abundance of attractive shrubs and small trees, with more kinds finding their way into cultivation all the time. A fine example is Hakea verrucosa, native to Western Australia in the continent’s winter-rainfall zone.
Hakea verrucosa is a shrub varying from 3 feet to 10 feet tall. It has narrow dark-green cylindrical leaves about one or two inches long, but despite its slender leaves it has a full appearance due to its dense branching.
Most species of Hakea have flower clusters that are either globes or cylinders, but in H. verrucosa they look like little corsages of red and white flowers. Each flower is white when it first opens, but turns pinkish-red and eventually deeper red as it ages.
This species flowers during the winter months, and a blooming bush is festooned with red and white clusters. These are best left on the plant, since they do not perform well as cut flowers.
Many Hakea species have interesting woody seed capsules, and H. verrucosa is no exception, although it does not often produce them in cultivation. When present, the capsules are about an inch or so long and rounded, except for a pair of horn-like projections at the tip. They are shiny and have a filigree pattern embossed on the surface.
Since Hakea verrucosa is relatively new to cultivation in California, not too much is known about its specific horticultural requirements. It does like a sunny position, and is known to tolerate cold down into the upper 20s during winter cold spells. In nature, it occurs on varying soil types, so presumably it will not prove too finicky as long as good drainage is provided.
Many members of the Protea Family are found in areas with low levels of phosphorus in the soil. As a result, these plants are hyper-efficient at extracting this nutrient, and can overdose if given high levels of it. To guard against this, at the Ruth Bancroft Garden we apply only fertilizers with low phosphorus levels. Excessive alkalinity should also be avoided in these plants.
It is worth noting that a few species in the genus Hakea, most notably Hakea sericea, have become invasive pests where they have been introduced in South Africa. For this reason, this species should be avoided, along with H. gibbosa, H. drupacea and H. salicifolia.
Brian Kemble is curator at the Ruth Bancroft Garden in Walnut Creek. His monthly column focuses on drought tolerant plants and dry gardens. Email questions to firstname.lastname@example.org. Learn more about the Ruth Bancroft Garden at www.ruthbancroftgarden.org.
Published at Tue, 19 Dec 2017 22:00:26 +0000