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Publication #ENH-164

Acacia farnesiana: Sweet Acacia1

Edward F. Gilman and Dennis G. Watson2

Introduction

This tall, semievergreen, native shrub or small tree has feathery, finely divided leaflets of a soft, medium green color. The slightly rough stems are a rich chocolate brown or grey, and possess long, sharp, multiple thorns. The small, yellow, puff-like flowers are very fragrant and appear in clusters in late winter then sporadically after each new flush of growth, providing nearly year-round bloom. The persistent fruits have a glossy coat and contain seeds which are cherished by birds and other wildlife.

Figure 1. 

Middle-aged Acacia farnesiana: Sweet Acacia


Credit:

Ed Gilman, UF/IFAS


[Click thumbnail to enlarge.]

General Information

Scientific name: Acacia farnesiana
Pronunciation: uh-KAY-shuh far-nee-zee-AY-nuh
Common name(s): Sweet Acacia, Huisache
Family: Leguminosae
USDA hardiness zones: 9A through 11 (Fig. 2)
Origin: native to North America
Invasive potential: little invasive potential
Uses: specimen; street without sidewalk; container or planter; reclamation; highway median; Bonsai
Availability: not native to North America

Figure 2. 

Range


[Click thumbnail to enlarge.]

Description

Height: 15 to 25 feet
Spread: 15 to 25 feet
Crown uniformity: irregular
Crown shape: vase, round, spreading
Crown density: open
Growth rate: slow
Texture: fine

Foliage

Leaf arrangement: alternate (Fig. 3)
Leaf type: bipinnately compound, even-pinnately compound
Leaf margin: entire
Leaf shape: linear
Leaf venation: pinnate
Leaf type and persistence: semievergreen
Leaf blade length: less than 2 inches
Leaf color: green
Fall color: no color change
Fall characteristic: not showy

Figure 3. 

Foliage


[Click thumbnail to enlarge.]

Flower

Flower color: yellow
Flower characteristics: very showy

Fruit

Fruit shape: pod or pod-like, elongated
Fruit length: 3 to 6 inches
Fruit covering: dry or hard
Fruit color: brown, green
Fruit characteristics: attracts birds; showy; fruit/leaves not a litter problem

Trunk and Branches

Trunk/bark/branches: branches droop; showy; typically multi-trunked; no thorns
Pruning requirement: needed for strong structure
Breakage: resistant
Current year twig color: brown
Current year twig thickness: thin
Wood specific gravity: unknown

Culture

Light requirement: full sun
Soil tolerances: clay; sand; loam; acidic; alkaline; well-drained; occasionally wet
Drought tolerance: high
Aerosol salt tolerance: moderate

Other

Roots: not a problem
Winter interest: no
Outstanding tree: no
Ozone sensitivity: unknown
Verticillium wilt susceptibility: resistant
Pest resistance: free of serious pests and diseases

Use and Management

It can be trained into a tree for use in median strips, or can be used as a street tree where there is not a need for tall-vehicle clearance beneath the crown. The small stature and low, spreading branching habit makes pruning for vehicular clearance difficult unless it is properly trained from an early age. But the required input of man hours for early training may be offset by the high drought, pest, and insect resistance of the tree. Do not locate the tree too close to where people can be injured by the sharp thorns on the branches.

Although easy to grow in any acid or alkaline soil, including clay, the leaves will drop if the soil is allowed to dry out. This drought avoidance mechanism allows the plant to grow well with no irrigation, once established. Growing best in full sun, this thorny, well-branched shrub makes an excellent barrier planting or nesting cover for wildlife. When trained as a small tree and used as a freestanding specimen, it is likely to provide a source for comments, such as "What's that?" But its growth rate is extremely slow, making it unpopular in the nursery trade but popular with those who care for it in the landscape. Sweet acacia has its place in any sunny shrub border or as an accent plant in any garden if located away from areas where children frequent, since the thorns can inflict severe pain. It is well suited for dry climates with little rainfall.

Propagation of sweet acacia is by seeds or cuttings.

Pests and Diseases

No pests or diseases are of major concern. Occasionally anthracnose can infect leaves.

Footnotes

1.

This document is ENH-164, one of a series of the Environmental Horticulture, UF/IFAS Extension. Original publication date November 1993. Reviewed February 2014. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Edward F. Gilman, professor, Environmental Horticulture Department; and Dennis G. Watson, former associate professor, Agricultural Engineering Department, UF/IFAS Extension, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.