Earleaf acacia
Scientific: Acacia auriculiformis
Common: Earleaf acacia, earpod wattle, northern black wattle
Family: Fabaceae
Introduction History: Introduced to Florida ~1930 for ornamental purposes [6].
General Description: Large, erect tree (20-100 ft). Often multi-trunked. Brown to grey-black bark forms fissures when mature. Wood is brittle and limbs are often subject to significant damagein high winds. [17, 18]
Habitat: Tolerates a wide range of soil environments. Found in flatwoods, scrub, and coastal areas of Florida – mostly dry, sandy conditions . Thrives in disturbed areas with high light availability/full sun. Tolerant of both drought and seasonal flooding [18].
Leaves: Although this plant appears to have prominent green leaves, these appendages are actually modified leaf stalks that function like a leaves. These modified leaf stalks are called phyllodes [16]. Phyllodes have 3-5 prominent veins which grow parallel along the curved shape [20].
Flowers: Earleaf acacia is monoecious, with plants bearing both male and female flowers. Flowers are yellow and form cylindrical spikes (~3 inches) either solitary or in clusters of 2-3 from the leaf axils [4]. These showy inflorescences form throughout spring to fall and tend to droop as they mature.
Fruit: Legume type fruit- flattened and oblong in shape. Fruit emerges green. Notably twisting and browning upon maturity, creating an ear-like shape [4].
Seeds: Seeds are dark brown to black and closely encircled by yellow aril- sometimes dangling by this upon ripening [9, 10, 17, 18, 19].
Other (Seedling ID): Seedlings emerge with pinnately compound cotyledons, followed by the development of phyllodes.
Rapid growth and high productivity produce dense monocultures, especially in disturbed sites. Outcompetes most other vegetation if not controlled [1, 5, 9, 10, 11, 17].
The debris of this plant is known to be allelopathic, meaning it produces chemicals which negatively impact nearby plants to reduce competition [7].
Fire adapted species- alters fuel composition and structure [1]. Seeds within seedbank benefit from post-fire conditions.
Rapid adaptation to environmental conditions of invaded range have contributed to the success of the species [13].
Certain mycorrhizal associations can modify natural nutrient regime of fragile habitats through nitrogen fixation and improve drought tolerance of individuals [14].
Regular monitoring and removal of plants can prevent the spread and establishment of earleaf acacia. Programs to educate homeowners on proper plant identification will also reduce the spread of this species. Native alternatives to earleaf acacia for use in home landscaping or natural areas include mastic (Masichodendron foetidissimum), mahogany (Swietenia mahagoni) and Florida soapberry (Sapindus saponaria).
Although currently only limited to South and Central Florida, rapid adaptation and global climate trends present significant risk for range expansion. Do not plant or disseminate any parts of this species [13, 17].
Control via solely mechanical methods is largely impractical or ineffective for large-scale applications. Earleaf acacia vigorously resprouts from cut stems and creates a robust and long-lived seedbank within the soil [15].
Extensive research has been conducted globally to implement biocontrol for earleaf acacia outside its native range. Currently, there are no approved biological control agents active in Florida. However, two insects are currently under study as potential biocontrol agents for earleaf acacia: Calomela intemerata, Trichilogaster sp. nov. [8, 11, 19].
Foliar applications are only feasible at young life-stages when plant height is below 3-4 ft. Basal bark treatment, cut stump, or hack and squirt are all effective methods. See our MANAGEMENT GUIDE FOR SPECIFIC DIRECTIONS.
