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Calopo (Calopogonium caeruleum)


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Common names 

Caeruleum calopo [English]; bejuco culebra, bejuco de lavar, calopogonio-perene, canela-araquan, chorreque, haba de burro, cama dulce, jicama [Spanish]; feijao-bravo, feijao-de-macaco, feijaozinho-da-mata, cipó-araquan, cipó-de-macaco [Portuguese]; thua sealulium [Thai]; Namie napirang, Klein Kau [Suriname]


Stenolobium caeruleum Benth.; Calopogonium coeruleum (Benth.) Sauvalle; Calopogonium coeruleum (Benth.) Sauvalle var. glabrescens (Benth.) Malme; Calopogonium sericeum (Benth.) Chodat & Hassler; Calopogonium sericeum (Benth.) Chodat & Hassler var. villicalyx Chodat & Hassler

Feed categories 

Caeruleum calopo (Calopogonium caeruleum (Benth.) C. Wright) is a climbing legume of the humid tropics, which is occasionally used for grazing but that has a poor palatability.


Calopogonium caeruleum is a twining and climbing perennial legume that becomes woody at maturity. The stems are pubescent to glabrescent and may be up to several meters long. They can root from the nodes when they are in contact with moist soil (FAO, 2015; Cook et al., 2005). The leaves are alternate, trifoliolate and borne on a long petiole (12 to 16 cm). The leaflets are hairy on one or both surfaces, rhomboid to ovate shaped, 5-20 cm long x 4-15 cm broad (FAO, 2015; Cook et al., 2005). The inflorescences are axillary borne elongated (25-50 cm) spike-like racemes. They bear many papillonaceous flowers. The flowers are blue, lavender to purple or violet in colour, about 1 cm long. The fruit is a dehiscent, pubescent, linear-oblong pod, 4 to 8 cm long, 8 mm wide, impressed between the seeds. The pods contain 4 to 8 compressed, shining seeds (Ecocrop, 2015; FAO, 2015; Cook et al., 2005). 


Calopogonium caeruleum is mainly grown in the humid tropics as a cover crop in tropical tree plantations. It is one of the most shade tolerant specis that can grow under rubber trees (Tajuddin, 1986). Due to its low palatability, It is rarely used as forage  (Chen et al., 1992). An N-fixing legume, it provides large amounts of biomass through leaf fall when it is used as green manure (Ecocrop, 2015; Cook et al., 2005; Chen et al., 1992). Caeruleum calopo has some allelopathic effects on weeds such as Imperata cylindrica (Fern, 2014).


Calopogonium caeruleum is a short-lived, slow growing perennial legume that originated from Mexico, Central America, and eastern tropical South America (North Argentina) and the West Indies (Chen et al., 1992). It was introduced to South Asia in the 1940s and is now widespread throughout the humid tropics (Chen et al., 1992). It can be found from sea level up to an altitude of 800 m. Though caeruleum calopo is adapted to the humid tropics where annual rainfall ranges between 1000 and 3000 mm and where day temperatures are within 18-25°C, it is tolerant of dryer (down to 700 mm rainfall/year) and cooler (down to 10°C) conditions and grows better than calopo (Calopogonium mucunoides), tropical kudzu (Pueraria phaseoloides) or centro (Centrosema pubescens) under such conditions (Cook et al., 2005; Chen et al., 1992). Caeruleum calopo can grow on a wide range of soil textures and soils provided they are well-drained. It withstands acidic soils with pH as low as 4 but responds well to P fertilizer and lime in such environments (Chen et al., 1992). Caeruleum calopo has some tolerance of soils containing Al3+. However at 7% Al3+ and above, the plant growth is hampered (Cook et al., 2005). It is outstandingly shade-tolerant and keeps producing under 0-25% sunlight in tree plantations. In a comparison in Malaysia, Calopogonium caeruleum was the best in overall shade tolerance among 14 other tropical legumes (Wong et al., 1985).

Forage management 


Caeruleum calopo can be grown in association with grasses or other legumes such as tropical kudzu (Pueraria phaseoloides), Desmodium ovalifolium, centro (Centrosema pubescens) or calopo (Calopogonium mucunoides) in tree plantations (Cook et al., 2005). Caeruleum calopo propagates better from seeds than from cuttings (only 5% survival). It should be sown into cultivated seedbed at the beginning of the rainy season and if it is sown in association with puero under oil palm it should be sown at 1:6 ratio (caeruleum calopo:puero). As caeruleum calopo does not establish very quickly, weeding is required on the early stages of growth (Cook et al., 2005).


Caeruleum calopo has relatively low yield potential, which could be increased by the inclusion of grasses and possibly other herbaceous legumes (Pillai et al., 1985; Middleton et al., 1982). It yielded 0.6 t DM/ha/year under heavy shade (0-25% sunlight) in oil palm (Chen et al., 1984).

Environmental impact 

Cover crop

Caeruleum calopo is mainly used as a cover crop in tropical tree plantations. In Nigeria, it was reported to develop quickly and covered the soil fully or almost fully (80-100%) within 10 or 14 weeks after sowing according to the soil environment (Muhr et al., 1999a). Caeruleum calopo planted in association with other legume or grass species under tree plantations (coconut, rubber and palm oil) was reported to suppress weeds, control soil erosion and to add nitrogen to the plantation crop (Stür et al., 1991). Calopogonium caeruleum outcompetes other species when light transmission decreases (Stür et al., 1991) because it has high shade tolerance (Reynolds, 1995).

Green manure

Caeruleum calopo has been successfully tested as a green manure before maize, and provided some the highest yields compared to other legume green manure (Muhr et al., 1999c). It has been tested for restoring soil fertility of fallow and prevent overgrazing due to its low cattle palatability (Muhr et al., 1999a). When caeruleum calopo is intended for green manure, it can be broadcasted into upland rice after final weeding (Cook et al., 2005). It was reported to provide large amounts of fallen leaves (7 t green leaves/ha/year) and about 90kg N equivalent/ha to the soil (Cook et al., 2005).

Weed potential

Caeruleum calopo has allelopathic effects on desirable grasses and smothers them. It may become a weed in tropical crops (Cook et al., 2005).

Nutritional aspects
Nutritional attributes 

Data on the nutritional qualities of Calopogonium caeruleum is extremely limited. Nigeria, according to the season and the soil quality, crude protein content ranged from 9 to 16% DM and the highest values were observed during the wet season (Muhr et al., 1999a). Phosphorus content was low (0.07-0.29% DM) with higher values in wet season and lower in dry season. Calcium content was high (0.8-2.3% DM) with few variations between the seasons (Muhr et al., 1999a). Like Calopogonium mucunoidesCalopogonium caeruleum is rich in fibre: NDF ranged between 65 and 68% DM and ADF ranged between 49 and 53% DM. Lignin content was also high (> 12% DM) (Muhr et al., 1999b).

Potential constraints 

Literature on Calopogonium caeruleum is scarce but no adverse effect has been reported except a very low palatability that is yet unexplained (as of September 2016). It contains polyphenols but not in such amounts (usually < 1% DM, Muhr et al., 1999b) that could cause rejection by livestock.


Very few trials have been conducted on the use of Calopogonium caeruleum on ruminants. The general consensus is that its low palatability makes it unsuitable for grazing.


Calopogonium caeruleum is not well consumed by ruminants. It has been reported to be avoided by sheep and cattle (Pillai et al., 1985; Middleton et al., 1982). It was referred to as a non-palatable cover crop species in rubber and oil palm plantations in Malaysia (Wahab, 2001). When caeruleum calopo is grown with other species, it is not or slightly consumed. Depending on climatic conditions or other causes, animals progressively overgraze the other species leading to their decrease until disappearance in extreme situations (Pillai et al., 1985; Middleton et al., 1982Chong et al., 1991). It is recommended to not cultivate Calopogonium caeruleum alone for grazing purpose and, when associated with other species, it is necessary to adapt carefully the stocking rate to the availability of the other species.


In sacco DM degradability (48 h) in both wet (50%) and dry (40%) season was quite low, which could be explained by the high fibre content (Muhr et al., 1999a).

Growing cattle

In Australia, Brahman cross steers (300 kg) allowed to graze continuously for 3 years a Guinea grass - Calopogonium caeruleum association at 2.5 to 3.75 steer/ha had an average daily weight gain of 0.49 to 0.54 kg/ha the first two years and only 0.2 kg/ha the last year when Guinea grass proportion dramatically decreased from an average of 50% to almost 0, and Calopogonium caeruleum proportion increased from 30 to 70% (Middleton et al., 1982).


Two studies in Malaysia led to similar negative results with sheep grazing multispecies pastures including Calopogonium caeruleum in rubber plantations. Under immature rubber trees  the proportion of the latter increased from 5 to 40% after 8 months (Pillai et al., 1985). When sheep grazed a pasture with a high yield of 2 to 2.5 t DM/ha under immature rubber trees at various stocking rates (4 to 14 sheep/ha), and were supplemented indoors with 100 g/d of palm kernel cake, they neglected Calopogonium caeruleum even at high stocking rates which led to 93-99% proportion of C. caeruleum after several months of grazing. The average daily weight gain decreased with increasing stocking rate from 106 to 84 g/d. Under mature rubber trees, pasture yield was much lower (0.5 to 0.8 t/ha) and sheep allowed to graze at 2 to 8 sheep/ha and supplemented indoors with 100 g/d of palm kernel cake consumed all forage species including C. caeruleum. Daily weight gain dramatically dropped from 99 to 26 g/d when stocking rate increased from 2 to 4 sheep/ha and was almost null (19 to 11 g/d) at the highest stocking rates (Chong et al., 1991).



No information found (2016).

Nutritional tables
Tables of chemical composition and nutritional value 

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 30.0       1  
Crude protein % DM 12.6 2.1 8.8 15.6 9  
Crude fibre % DM 34.0       1  
NDF % DM 66.6   64.7 68.4 2  
ADF % DM 50.8   49.1 52.5 2  
Lignin % DM 12.8   12.7 12.8 2  
Ether extract % DM 3.0       1  
Ash % DM 3.0       1  
Gross energy MJ/kg DM 19.7         *
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 14.1 6.1 8.0 22.5 6  
Phosphorus g/kg DM 1.6 0.9 0.7 2.9 6  
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 61.2         *
Energy digestibility, ruminants % 58.5         *
DE ruminants MJ/kg DM 11.5         *
ME ruminants MJ/kg DM 9.3         *

The asterisk * indicates that the average value was obtained by an equation.


Hartadi et al., 2005; Muhr et al., 1999; Muhr et al., 1999

Last updated on 18/09/2016 01:18:39

Datasheet citation 

Heuzé V., Tran G., Hassoun P., Lebas F., 2016. Calopo (Calopogonium caeruleum). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/587 Last updated on October 21, 2016, 16:31

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