Acacia melanoxylon (Black Acacia) is very quick-growing tree to 40 feet tall or much more with a 20 feet wide and in maturity an oval shaped crown. It has rough dark gray bark with vertical fissures and mid-green leaf-like flattened stems, called "phyllodes", that are 3 to 5 inches long by about an inch wide with one margin straight and the other curved. Small creamy flowers are in a small ball-like cluster from late winter into spring and are followed by thin curling seed pods that hang in brownish sheaves. A durable tree for quick growth, screening and erosion control, however its fire prone nature makes it unsuitable for WUI locations in Marin. The aggressive roots can lift sidewalks, damage foundations and plumbing and together with leaf, seed pod and branch litter and its propensity to sucker and reseed, makes this tree not ideal for street plantings or near living areas.
Acacia trees are not recommended due to their fire prone nature. Consider removing acacia trees within 100' of structures. If a tree must be maintained in the defensible space zone (within 100' of structures or 15' of roadways), extreme care should be taken to reduce the associated wildfire hazard.
Remove all limbs within 10' of the ground, or 1/3 the height of the tree if less than 30' tall
Remove all dead wood and twiggy growth regularly
Provide canopy separation so that no limbs touch nearby trees or plants
Remove all "ladder fuels," shrubs, and immature trees growing below
Remove fallen needles and detritus regularly
Remove any leaves or twigs which fall on the roofs of nearby buildings, and repeat regularly during fire-season