Weed Identification

Australia > > Leucaena

Leucaena

Leucaena leucocephala

Family: Fabaceae.

Form: Tree

Origin: Native of tropical America.

Flowers/Seedhead: In heads 1.22.1 cm wide, green to whitish, over 80 flowers per head, 13 heads in leaf axils or several in terminal racemes, on stalks 26.5 cm long. Flowers summer and autumn.

Description: Shrub or tree to 10 (rarely to 20) m high. Bark smooth with prominent raised areas (lenticels).Young branches finely hairy to hairless. Seedpods 822.5 cm long, 1.32.7 cm wide. Seeds 510 mm long and 36 mm wide, glossy, brown.

Distinguishing features: Distinguished by being spineless; leaves bipinnate, leaf axis (rachis) 4.514 cm long, pinnae in 310 pairs, leaflets 521 mm long, 15 mm wide in 522 pairs, hairless or margins with fine very short hairs, gland often at or below junction of the lowest pinnae pair; flowers bisexual, stamens 10, anthers hairy.

Dispersal: Spread by seed: by wind, water, in cattle manure and movement of contaminated soil, hay and machinery.


Flowers in heads and bipinnate leaves,
Brisbane, Qld, April

Notes: Cultivated for fodder and widely planted in tropical and sub tropical Australia. Leucaena is a serious environmental weed that forms dense thickets excluding other plants. Plants contains mimosine and are toxic to stock if eaten in large quantities. Plants grow in areas with over 650 mm rainfall per year, are frost and fire sensitive and prefer deep, well drained slightly acid to alkaline soils. Two subspecies (ssp.), ssp. glabrata (the preferred fodder ssp.) with hairless new growth, and ssp. leucocephala with hairy new growth, are grown in Australia. Both ssp. are weedy.

References:

    Plant Protection Quarterly. C.Walton, 2003, Vol. 18, pages 9098.

Web References: Search Australian web sites for further information on this weed.


Pod and seeds, Charters Towers, Qld

Tree growing in Darwin, NT

This weed has been included in the WEEDeck field guide as card T20

More information about WEEDeck is available from Sainty & Associates Pty. Ltd.

 

Australia > > Leucaena

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