Two important trees for wildlife gardening are easily identified from a distance
Published April 3, 2022, Harlingen’s Valley Morning Star.
Story and photos by Anita Westervelt, Texas Master Naturalist, South Texas Border Chapter
It is easy to be an expert identifier this time of year when the landscape is full of colorful blooming trees. Two trees readily recognized from a distance are the yellow haze of Texas huisache (Acacia farnesiana [A.smallii]) and white-blooming blackbrush (Acacia rigidula).
Small, round, golden, pollen-rich, puffy pom-poms of richly fragrant flowers line the branches of Texas huisache. With regular watering, it can grow rapidly to15 to 30 feet tall. Keep as a multi-trunked, dense shrub or prune to form a traditional tree shape. It is an important nesting tree for white-winged doves; migrating warblers feed on the pollen and the insects attracted to the pollen.
Texas huisache easily propagates from seed. Short, two- to three-inch long seedpods follow the flowers. The seeds inside take four to six months to ripen. Pods harden and dry, turning almost woody and remain on the tree. Beware the long, paired, straight spines at the bases of the leaves.
White-tailed deer and javelina eat the fresh seedpods, and quail eat the seeds after the pods open and drop the seeds. Quail, doves and other birds use this plant to nest, rest and as cover.
Blackbrush is a prolific bloomer in spring; clusters of fragrant three-inch long blossom spikes contrast starkly with the dark branches. Blooms appear before the dark green, heavily ribbed leaves are fully out. The creamy white to golden-yellow flowers are a source of honey. Bees, butterflies, moths and other nectar-insects benefit from the flowers.
Considered a large shrub, blackbrush is multi-stemmed, thorny, with stiff paired spines that can reach to two inches long on rigid, zigzag branches. The shrub can reach heights of 10 to 20 feet and spread nearly as wide. It is slow-growing and long-living.
The seedpods are a legume about two to four inches long, narrow, curved and flat; reddish brown when ripe. Many birds and small mammals rely on blackbrush for food, cover and protection. Chachalacas and northern bobwhite quail and other granivorous birds eat the seeds. Long- and curved-billed thrashers, cactus wrens and scissor-tailed flycatchers have been known to nest in its dense branches.
Chaparral and thrornforest are blackbrush’s traditional habitat in the middle and lower Rio Grande Valley. It is a larval food plant for some butterflies and moths in its range: Mexican yellow, mimosa yellow and Reakirt’s blue butterflies and the black witch moth, merry melipotis, mesquite stinger flannel and the orangeworm moths.
Both species are adaptable to any soil, from sandy to loam, caliche and even the heaviest clay. Once established, they withstand drought, freeze, heat and sun; both are excellent species for xeriscapes and rock gardening.
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