City Trees

Tree of Merit: Blue Jacaranda ( Jacaranda mimosifolia) Blue jacaranda ( Jacaranda mimosifolia) is native to central and east- ern South America and can be found across the world in subtropical and warm climates. It's a USDA Zone 10 -11 species but is said to tolerate occasional brief dips slightly below f reezing temperature. It prefers full sun but can tolerate par tial shade and has been known to be drought-tolerant during periods of extended dr y weather. In Brisbane, Australia, blue jacaranda it is of ten planted as a park feature tree in avenues or groups due to its iconic show y carpet of lilac-blue trumpet f lowers that drop in November before it grows its new leaves. The f lowering period is only up to three weeks ever y year but proves a stunning spectacle. The mature height can var y depending on the site conditions, f rom as small as 9m ( 30 feet) up to 25m (82 feet). Its success as a street tree is largely dependent on the amount of growing space and the site conditions it's given; like so many tree species, jaca- randa is most suited to larger sites where the tree can benef it f rom moist soil. I have found that many jacarandas planted too close to footpaths fail to thrive, stunted or sometimes even entering early senescence due to the stress of the constrained site conditions. It does not like exposed or windy sites; as a young tree it needs to be staked to keep it growing straight and strong. Jacaranda does benef it f rom formative pruning at years three and seven af ter planting. It can be grown f rom both seed and cut tings. Jacaranda trees have an inner canopy that is def ined by a dif ferent t ype of bark. The trunk and major scaf folding limbs have a rough bark , but the inner canopy has a smooth grey bark. Up to ten years ago, within the local arboriculture industr y these smaller limbs were pruned because they were thought to be a t ype of epicormic grow th. However, experience has shown the inner canopy need not be pruned unless for health or other structural reasons. by Sitara Gare, Arboriculture Coordinator, Brisbane City Council, Australia Sitara Gare is an Arboriculture Coordinator for Brisbane City Council, Australia's largest municipal council. Her arboriculture passions lie in educating the public about all the benefits of trees. Blue jacaranda flowers. Photo Courtesy Missouri Botanical Garden Plant Finder Blue jacaranda bark. Photo by KENPEL via Wikimedia Commons Leaves and seed pods of blue jacaranda. Photo by Carla Antonini via Wikimedia Commons

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