Leucaena Benth.

Leguminosae, J.P.M. Brenan. Flora Zambesiaca 3:1. 1970

Morphology General Habit

Trees or shrubs, unarmed.

Morphology Leaves

Leaves 2-pinnate; a gland often present at the junction of the lowest pair of pinnae, petiole and rhachis otherwise eglandular, or rarely with glands between other pairs of pinnae; pinnae each with one to several or many pairs of leaflets.

Morphology Reproductive morphology Inflorescences

Inflorescences of rounded heads, pedunculate, axillary, 1-3 together, often racemosely aggregated.

Morphology Reproductive morphology Flowers

Flowers hermaphrodite, sessile.

Morphology Reproductive morphology Flowers Calyx

Calyx gamosepalous with 5 teeth.

Morphology Reproductive morphology Flowers Corolla

Petals 5, free, pubescent to glabrous outside.

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 10, fertile.

Morphology Reproductive morphology Flowers Androecium Stamens Anthers

Anthers eglandular at the apex (except in the extra-African L. forsteri).

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary pubescent or sometimes glabrous.

Morphology Reproductive morphology Fruits

Pods oblong or linear-oblong, compressed, usually thinly subcoriaceous, splitting into 2 non-recurving valves.

Morphology Reproductive morphology Seeds

Seeds lying ± transversely in the pod, compressed, brown, glossy, unwinged, with endosperm.

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Trees or shrubs, unarmed

Morphology Leaves

Leaves bipinnate

Morphology Reproductive morphology Inflorescences

Flowers bisexual, sessile, in round heads

Morphology Reproductive morphology Flowers Calyx

Calyx 5-lobed

Morphology Reproductive morphology Flowers Corolla

Corolla of 5 free petals

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 10; anthers eglandular at apex

Morphology Reproductive morphology Fruits

Pods oblong or linear-oblong, flattened, splitting into 2 non-recurving valves.

Distribution

Some 25 species, all tropical American, but one widely cultivated.

Timothy M. A. Utteridge and Laura V. S. Jennings (2022). Trees of New Guinea. Kew Publishing. Royal Botanic Gardens, Kew

Distribution

A genus of 22 species from the Neotropics. One species is cultivated and naturalised throughout the tropics, including New Guinea: Leucaena leucocephala (Lam.) deWit. The description below applies only to this species.

Morphology General Habit

Trees and shrubs to 10(–15) m tall, unarmed

Morphology Leaves Stipules

Stipules caducous

Morphology Leaves

Leaves bipinnate, gland usually present between lowest pair of pinnae, leaflets opposite, base slightly asymmetric. Inflorescences axillary or teminal, pedunculate glomerules, sometimes forming compound pseudo-racemes

Morphology Reproductive morphology Flowers

Flowers bisexual, uniform, 5-merous; calyx campanulate with triangular teeth; petals spathulate, free; stamens 10, free, anthers sparsely hairy, anther glands absent; ovary stipitate

Morphology Reproductive morphology Fruits

Fruit membranous, oblong to linear, straight, flat, dehiscent along both sutures

Morphology Reproductive morphology Seeds

Seeds arranged transversely, ovate to oblong, testa glossy brown.

Recognition

Leucaena leucocephala is a shrub or small tree with leaflets which often have a glaucous or grey tinge when fresh, cream-coloured globose inflorescences, 10 free stamens, and clusters of straight, brown pods with seeds arranged centrally and orientated transversely.

Legumes of the World. Edited by G. Lewis, B. Schrire, B. MacKinder & M. Lock. Royal Botanic Gardens, Kew. (2005)

Note

The tribe Mimoseae (sensu Bentham, 1875) is retained here simply as a matter of convenience. All recent phylogenetic analyses indicate that Ingeae and Acacieae are derived from within Mimoseae (Chappill & Maslin, 1995; Käss & Wink, 1996; Luckow et al., 2000; Bruneau et al., 2001; Luckow et al., 2003; Herendeen et al., 2003a), making it a paraphyletic group at best. The most recent studies indicate that it may not even be monophyletic with respect to the Caesalpinioideae (Luckow et al., 2000; Bruneau et al., 2001; Luckow et al., 2003).

Although the outline of a new tribal classification of the mimosoids is emerging, we await better-supported phylogenies (based on more extensive data) before formalising new stable and useful groups. Some parts of the classification proposed here are better supported than others. Notably, the basal branches in Fig. 24 are poorly supported in most analyses and the relationships among the groups are likely to change as we acquire more data. As presently indicated (Luckow et al., 2003), the type genus Mimosa falls within the derived Piptadenia group which is in turn sister, and basally branching, to elements of Acacia and Ingeae (Fig. 24). A more narrowly circumscribed Mimoseae sens. strict. will thus leave the bulk of Mimoseae sens. lat. (i.e., as treated here) in need of new tribal allocation. The most conspicuous difference between the classification presented here and that of Lewis & Elias (1981) is the inclusion of tribe Parkieae within Mimoseae. The former was circumscribed based on imbricate aestivation of the calyx, and was considered the basal tribe within the Mimosoideae (Elias, 1981a). Recent phylogenetic analyses (Chappill & Maslin, 1995; Luckow et al., 2000; Bruneau et al., 2001; Luckow et al., 2003; Herendeen et al., 2003a), indicate that the two genera in the Parkieae, Parkia and Pentaclethra, are not sister taxa (Fig. 24). Pentaclethra is nested within Mimoseae in Luckow et al. (2000), but is either sister to caesalpinioid taxa in Bruneau et al. (2001) and Herendeen et al. (2003a), or part of a basal polytomy with Mimoseae and caesalpinioid taxa (Luckow et al., 2003). Both Parkia and Pentaclethra are included in the tribe Mimoseae pending additional data and tribal recircumscription.

Recent work (Luckow et al., submitted a) also indicates that the monospecific tribe Mimozygantheae should be subsumed in the Mimoseae near Piptadeniopsis and Prosopidastrum, currently in the Prosopis group. Otherwise, the informal groups within the Mimoseae recognised by Lewis & Elias (1981) are relatively well-supported by current phylogenies and only a few departures have been made from their system. Where relationships are either poorly supported or unresolved, the classification of Lewis & Elias (1981) is retained. The Xylia group is dismantled and the Adenanthera group recircumscribed to include Calpocalyx and Xylia . Desmanthus has been removed from the Dichrostachys group, as has Neptunia, in agreement with recent molecular and morphological phylogenetic studies (Harris et al., 1994; Hughes, 1998; Luckow, 1995, 1997). A new group is erected to accommodate Piptadeniastrum which is well separated from Newtonia in the most recent phylogeny (Luckow et al., 2000; 2003), and another to accommodate Cylicodiscus, which is more closely related to the clade containing the Prosopis, Leucaena, Dichrostachys, and Piptadenia groups than it is to the Newtonia group. Neptunia is well supported as sister to Prosopidastrum in recent analyses (Luckow et al., 2003) and is included in the Prosopis group here. Relationships of genera in the Prosopis group are not resolved, but the group is retained here as there is no evidence that it is not monophyletic. Genera newly described since 1981 include Alantsilodendron, Calliandropsis, Kanaloa, and Lemurodendron. Alantsilodendron and Calliandropsis are placed in the Dichrostachys group, and Kanaloa in the Leucaena group based on phylogenetic analyses (Hughes, 1998; Luckow, 1997; Luckow et al., 2000). Lemurodendron is tentatively included in the Newtonia group as suggested by Villiers & Guinet (1989). As treated here the Mimoseae comprises 40 genera and from (859)– 869–(879) species.

Placed in a well supported clade sister to Schleinitzia, Kanaloa and Desmanthus (Luckow et al., 2003; Hughes et al., 2003), in the Leucaena group

Habit

Trees and shrubs

Ecology

Tropical and subtropical seasonally dry forest, semi-arid thorn scrub forest, to warm temperate open habitats

Distribution

Mexico (10 endemic spp. with 2 extending to S USA [Texas and New Mexico] and 4 spp. to C America); 4 endemic spp. in C America; 1 sp. in S America (N and W coastal regions S to Peru); 1 sp. pantropical

George R. Proctor (2012). Flora of the Cayman Isands (Second Edition). Royal Botanic Gardens, Kew

Morphology General Habit

Unarmed shrubs or small trees; leaves bipinnate, usually with a gland on the petiole; stipules small

Morphology Reproductive morphology Flowers

Flowers white, in globose, stalked, many-flowered heads, the peduncles solitary or clustered in the leaf-axils, or sometimes arranged in terminal naked racemes, each peduncle bearing 2 bracts at or below the apex

Morphology Reproductive morphology Flowers Calyx

Calyx tubular, 5-toothed; petals 5, free, valvate

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 10, free, exserted, the anthers often hairy

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary stalked, with filiform style; ovules many

Morphology Reproductive morphology Fruits

Pods oblong-linear, flat, 2-valved, continuous within, short- stalked; seeds transverse, compressed-ovoid.

Distribution

An American genus of perhaps as many as 50 species, but probably fewer.

Use

Leucaena leucocephala (Lam.) de Wit (leucaena, koa haole, jumbie bean, guaje, ipil-ipil) is cultivated pantropically and has become naturalised and weedy in many areas; this and other species are used for livestock feed, green manure, timber (for construction, firewood and charcoal), small wood products, soil conservation (ground cover and reforestation) and human food (unripe pods and seeds)