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Albizia julibrissin Durazz.
FM: Leguminosae Control LF: Deciduous tree Trees can be cut at ground level; the best time is when trees have SN: Acacia julibrissin (Durazz.) Willd., Acacia mollis Wall. begun to flower in order to prevent seed set. Since resprouts will CU: Ornamental quickly emerge, repeated cutting or herbicide treatment is needed CN: Mimosa, pink siris, silktree, varay-cotton to achieve long-term control. Girdling is effective to kill large trees but follow-up programmes to control resprouts will be necessary. Invaded Habitats Young seedlings can be hand-pulled, which is best done after rain Forest edges, disturbed sites. when the soil is loose. Care should be taken to remove the entire root since broken fragments may resprout (Remaley, 2005b). Description Chemical control of seedlings and small trees is achieved by Shrub or tree up to 16 m tall, spreading and low-branched with a spraying with glyphosate or triclopyr. The cut stump and basal bark broad crown. Trunk short, bark light brown to greyish, nearly application of herbicide is appropriate for larger trees. For cut smooth. Leaves alternate, bipinnately compound, 10–35 cm long stump treatments, stems should be cut at or near ground level and and up to 15 cm wide, with 6–25 pinnae each having 40–60 leaflets. painted with glyphosate or triclopyr. These herbicides are also ef- These are oblong, 5–15 mm long, 2–5 mm wide, ciliate, sometimes fective as basal bark applications (Remaley, 2005b). Other effective pubescent on midrib beneath, asymmetric with the middle nerve lo- herbicides for treating cut stumps or saplings are aminocyclopyra- cated along the upper edge. Flowers light to dark pink, c. 3.5 cm chlor, clopyralid and fluroxypyr (Koepke-Hillet al ., 2012). long, borne in heads that are clustered at the end of branchlets. Fruits yellow-green flattened pods, up to 15 cm long and 2–3 cm wide. Seeds ovate, c. 3.5 mm long and 1.8 mm wide, with hard seed coat (FOC, 2014).
Ecology and Impacts Where native, this fast-growing and short-lived tree grows in a var- iety of soils including salty soils and soils with high pH values (Orwa et al., 2009). Primary habitats include scrub and open wood- land on moist sites. It grows best in full sun but can tolerate partial shade. It does not occur in closed forests. The tree produces large seed crops and easily resprouts when damaged. Sprouts can grow c. 1 m in a season (Remaley, 2005b). The tree is widely used as an ornamental for its fragrant and showy flowers and was introduced to the USA as early as 1745 (Remaley, 2005b). It has become invasive because it is a strong competitor to native trees and shrubs in forest edges and other open areas. It forms dense stands that reduce light levels Albizia julibrissin. From 4028mdk09, published under a creative commons and nutrients, preventing the establishment of native plants. This is license (http://creativecommons.org/licenses/by/3.0/) especially a problem in riparian habitats, which are usually of high conservation value. The tree is nitrogen- fixing, usually abundantly nodulated and well adapted to poor soils (Orwa et al., 2009). It is resistant to drought and tolerates moderate frosts. Seeds are carried by water and can remain dormant for many years due to their hard seed coats (Remaley, 2005b). A native seed predator, Bruchidius terrenus (Coleop- tera: Chrysomelidae) has been observed in the USA since 2004 (Hoebeke et al., 2009; Chang et al., 2011).
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