Calliandra (Calliandra calothyrsus Meisn.) is a small tropical legume tree valued for its multipurpose attributes. Used in agroforestry systems, it yields many products (fuelwood, fodder, fibre, honey, shellac) and provides services (shade, erosion control, weed control, soil improvement, as an ornamental plant, etc.) (Orwa et al., 2009; Palmer et al., 1994; Wiersum et al., 1997). A very versatile species, calliandra does well under a wide range of soils and is outstanding in those of low fertility (Wiersum et al., 1997).
Calliandra is an almost evergreen, thornless small legume tree, usually about 5-6 m high, but it can reach a height of 12 m. It has a straight trunk up to 30 cm in diameter and many branches that form a dense canopy (Orwa et al., 2009; Palmer et al., 1994). The bark is very variable in colour, from white to red brown or blackish brown (Orwa et al., 2009; Palmer et al., 1994; Wiersum et al., 1997). It is mainly glabrous but can also be finely pubescent (FAO, 2016). Calliandra has a fast growing, vigorous root system that develops down to a depth of 1.5-2 m within 4-5 months. The root system encompasses both superficial adventitious roots and deep growing roots, sometimes developing a taproot (Orwa et al., 2009). Calliandra roots nodulate with Rhizobium strains. New sprouts are readily formed from the root system and facilitate coppicing. Under annual coppicing of stems of 3-5 cm diameter, the tree can survive for many years (FAO, 2016).
Calliandra leaves are alternate and bipinnately compound, the rachis being 10-19 cm long and bearing (3-)6-20 pinnae. The pinnae are 4-7 cm long and encompass 19-60 pairs of linear, opposite, acute or obtuse leaflets, 5-8 mm long x 1 mm wide (Palmer et al., 1994; Wiersum et al., 1997). The inflorescence, borne at the apex, is a showy spike-like raceme 10-30 cm in length. It bears several clusters of purplish-red flowers that are 4-6 cm long with very conspicuous stamens, hence the name “calliandra” ("beautiful male"). The fruits are broadly linear, flattened, pubescent, dehiscent pods, 8-11 cm long x 1 cm broad, and brown in colour. They contain 3-15 seeds. The seeds are ellipsoid, flattened, 5-7 mm long, and mottled dark brown in colour (Palmer et al., 1994; Wiersum et al., 1997).
Calliandra was not much used in its native range (Central America and Mexico) and only became a valued multi-purpose legume tree after it was introduced into Indonesia (Orwa et al., 2009; Palmer et al., 1994). Calliandra firewood has a good calorific value and a low moisture content, thus requiring less drying. It burns very quickly and is particularly suited for charcoal production. One hectare of calliandra can produce 14 tons of charcoal per year. Calliandra wood is a useful smoking fuel that can replace rubber wood. Calliandra can produce 15-40 tons wood/ha/year under annual coppicing, and it remains productive for 10-20 years (Orwa et al., 2009; Wiersum et al., 1997). It has been positively assessed for biofuel (bioethanol) production in India (Adaganti et al., 2014). Calliandra wood is a source of fibre, pulp and paper (Wiersum et al., 1997). Calliandra is a good source of nectar for the production of high quality honey. Calliandra hosts a shellac-producing insect (Laccifer lacca) (Wiersum et al., 1997). Calliandra is a beautiful tree that is thus used as an ornamental tree in towns and gardens (Orwa et al., 2009). It provides environmental services such as erosion control, weed control, soil improvement, intercropping and alley cropping, shelter and as a plantation nurse species (see Environmental impact below).
Calliandra is a valuable fodder for all classes of ruminants. Leaves and pods contain large amounts of protein and are free of toxic substances. However, its high tannin content makes it less useable for pigs and poultry.