Couroupita guianensis Aubl.

• Title

  Couroupita guianensis Aubl.

• Description

  Description: Trees, to 35 m tall, unbuttressed. Bark not fissured. Leaves in clusters at ends of branches; petioles 5-30 mm long; blades (6-)8-31(-57) 3-10 cm, usually narrowly obovate to obovate, sometimes elliptic, glabrous adaxially, pubescent on veins abaxially, often with a tuft of trichomes (possibly domatia) in axils of secondary veins; base cuneate; margins entire; apex generally acute or acuminate; secondary veins in 15-25 pairs, the tertiary veins weakly percurrent, the higher order venation forming well-defined areoles. Inflorescences cauline, usually unbranched racemes, sometimes branched and paniculate, sometimes covering entire trunk; pedicels 12-60 mm long. Flowers zygomorphic, 5-6 cm diam.; calyx-lobes 6, imbricate, the margins ciliate; petals 6, most commonly yellow toward apices and pink to red toward bases abaxially, pink to red except for white bases adaxially; androecium prolonged on one side into flat hood, with stamen free area between staminal ring and hood proper, the hood white or pale yellow tinged with pink externally, the ring stamens with white filaments and pale yellow anthers, the hood staminodes often white at very base, pink for most of length, and yellow at apex, sometimes white for most of length and yellow at apex, the stamens with lateral dehiscence; ovary inferior, 6-locular. Fruits indehiscent, globose, 12-25 cm diam., falling from tree at maturity. Seeds embedded in pulp, the pulp oxidizing bluish-green when exposed to air, the testa with trichomes; embryo with 2 foliaceous cotyledons. Diagnostic features: The combination of tufts of trichomes in the axils of the secondary veins; conspicuous inflorescences arising from the trunk; showy aromatic flowers with the petals tinged with various degrees of pink or red and a flat androecial hood; cannon-ball like fruits; and seeds embedded in a pulp that oxidized bluish-green when exposed to the air separate this species from all other Lecythidaceae. It can only be mistaken for the other two species of the genus, C. subsessilis found along Amazonian rivers and the Central American C. nicaraguarensis. In fruit, these three species are difficult to identify. However, in flower they are easily separated. Both C. subsessilis and C. nicaraguarensis have white or pale yellow flowers. In addition, C. subsessilis has a notched androecial hood and C. nicaraguarensis has stamens that run from the staminal ring all of the way onto the hood. Common names: Cannon-ball tree (English), bola de cañon (Spanish), granadillo de las huacas (Panama), Coco sachapura, maraco (Colombia), coco de mono, mamey hediono, muco, taparo de monte (Venezuela), boskalebas, iwadaballi, kaupe (Surinam), kouroupitoumou (French Guiana), castanha de macaco (Brazil). Distribution (map): Panama, Amazonian Colombia, northern Venezuela, Guyana, Surinam, French Guiana, Amazonian Ecuador, Amazonian Peru, and eastern and southwestern Amazonian Brazil. This species has been collected in Costa Rica but these collections come from cultivated trees. In South America, Couroupita guianensis is found mostly around the periphery of the Amazon Basin, displaying a distribution pattern called peri-Amazonian by Granville (1992). This species is frequently planted as a botanical curiosity in tropical and subtropical botanical gardens in many parts of the world. Ecology: We know of no ecological studies of C. guianenensis in which frequency, density, dominance, and habitat preferences have been reported. We have seen trees in lowland forests in non-flooded habitats Phenology: Poiteau (1825) observed that trees of this species growing in their native habitat in sandy soils on the Ile de Cayenne, French Guiana lost their leaves in March and again in September, remained 18 days almost leafless, and then flowered and flushed new leaves. Ormond et al. (1985) made observations on leaf fall, leaf flush, flowering, and fruiting during five-years on 13 trees of Couroupita guianensis growing outside their native range in the botanical garden of the Museu Nacaional in Rio de Janeiro. These trees dropped and flushed new leaves two to three times a year. The leaves turn yellow, fall to the ground, and flush leaves within 15 days after the old leaves have fallen. Leaves were most frequently flushed just before the onset of flowering and there was little synchrony in leaf fall and flush among the trees they observed. The trees flowered from November through May with a peak in January and February with any given tree flowering one to three times during this period. The trunks of some trees were covered by flowering inflorescences that reached as long as 80 cm. and a given tree held as many as 1000 open flowers per day. Fruits in this area fell from October through April. Pollination: The morphology and development of the flowers of C. guianensis have been well illustrated by Thompson (1921). In addition to being showy, its flowers are strongly and pleasantly aromatic. Ormond et al. (1981, 1982) determined that the osmphores of this species are most abundant on the hood filaments and less common on the adaxial surface of the petals. Oil droplets are found in the cells of the epidermal and stomatal guard cells of the osmophores. In addition, the cells of the mesophyll of these structures are rich in starch. After anthesis, oil droplets and starch are not nearly as plentiful. The internal temperature of the flowers at anthesis is seven degrees above the ambient temperature. Ormond et al. (1981, 1982) suggest that the oil droplets volatilize to yield the pleasant aroma and that the starch in the adjacent cells provides the energy for this process. The aroma, at least in some individuals, is dominated by monoterpene hydrocarbons (Knudsen & Mori, 1996).The apices of the hood filaments are yellow, a color that attracts bees. Moreover, UV light is only reflected from the hood and has perhaps evolved to attract pollinators to rewards found in that part of the flower. The sweet aroma of these flowers is strongest in the early morning and bees have been recorded visiting the flowers as early as 5:00 a.m.; the petals and androecium drop from the flowers around 12:00 p.m. (Ormond et al., 1981). Yarsick et al. (1986) report that the flowers of a cultivated Venezuelan tree open gradually between 7:00 and 8:30 p.m. with the hood and ring anthers opening simultaneously. These authors confirm observations that the hood anthers are larger than the ring anthers - the former have an average of 2,850 tetrads and the latter 450 monads per anther. The flowers of C. guianensis are without nectar and are mostly visited by bees in search of pollen. Xylocopa brasilianorum has been reported to be the principal pollinator outside of the native range of C. guianensis in the botanical garden of the Museu Nacional in Rio de Janeiro. Dahlgren (1924) states "The large black bumble-bees that visit the flowers force their way under the tip of the hood, between the two sets of stamens, and become thoroughly dusted with pollen." It is likely that the bees observed by Dahlgren also represent a species of Xylocopa. Yarsick et al. (1986) report bees, wasps, and a flower fly visiting the flowers, but note that Xylocopa frontalis and a species of Bombus appear to be the most efficient pollinators. Carpenter bees of the genus Xylocopa have also been observed pollinating cultivated trees of C. guianensis in India (Aluri & Reddi, 1990). Ormond et al. (1981) have demonstrated that bagged flowers do not set fruit nor do the flowers in the bags end up with pollen on their stigmas. They demonstrated that two percent of artificially self pollinated flowers produce fruit whereas artificially cross-pollinated and naturally pollinated flowers yield 6% and 4% fruit respectively. In their study, they observed a tree flowering out of phase with the other trees set fruit, and there are other unsubstantiated reports of cultivated trees growing in isolation producing fruit. Thus, it appears that C. guianensis is self-compatible, but that there are more fruits set if out crossing takes place. Poiteau (1825) observed that the pollen of the hood was larger and yellow and that of the staminal ring smaller and white. Thompson (1927) was the first to suggest that pollen from the hood does not germinate on the stigma, but it was Jacques (1965) who first observed that the ring and hood pollen are different. This observation has been confirmed by Mori et al. (1980), Ormond et al. (1981), and Yarsick et al. (1986). These authors have demonstrated that the pollen of the staminal ring is found in monads and has a smooth exine while that of the hood is in tetrads and has a rougher exine. Ormond et al. (1981) add that the ring pollen is covered with droplets of a lipid substance whereas that of the hood is dry. Examination of the stigma shows that monad pollen dominates the surface while tetrad pollen is rarely found there. The ring pollen shows a high degree of both in vitro and in vivo germination whereas not a single pollen grain from the hood anthers germinates (Mori et al., 1980; Ormond et al., 1981). In conclusion, it has been clearly demonstrated that there are two types of pollen in the flower of Couroupita guianensis and that the most likely pollinators are species of large bees, such as Bombus and Xylocopa, which are rewarded for their efforts with non-germinating pollen that they collect from the hood. Dispersal: Fruits from different trees of C. guianensis display considerable variation in size, ranging from 12 to 25 cm in diameter with smaller ones having as few as 65 and larger ones as many as 550 seeds (Ormond et al., 1985; Schoenberg, 1983a). The number of fruits produced per tree ranges from 50 to 150. Fruits reach maturity in about 12 months (Ormond et al., 1985), but Dahlgren (1824) noted that it takes as long as 18 months for fruits of this species to mature in Guyana. The number of flowers and fruits produced by individuals of C. guianensis vary from one flowering period to the next, sometimes there is a major flowering and other times the flowering is minor. Fruit set is 0.8% following a major flowering and 3.4% after minor flowering, but major and minor flowering events usually yield about the same number of fruits produced because of the greater number of flowers available during a major flowering period (Ormond et al., 1985). The anatomy and morphology of the fruits of Couroupita guianensis have been described in detail by Schoenberg (1983a, 1983b). The cannon-ball like fruits of Couroupita guianensis fall and often crack open upon hitting the ground. The seeds are embedded in a six-segmented fleshy pulp that oxidizes bluish-green when exposed to the air. Peccaries and domestic animals, such as chickens and pigs, are reported to eat the pulp and in so doing swallow the seeds. Prance and Mori (1979) report an observation made by H. W. Koepcke who studied a tree of this species over a three-week period. The ground under the tree was covered by many fruits which remained untouched until a herd of peccaries passed by and broke open the fruits and consumed the pulp. The seeds of species of Couroupita have exotestal trichomes which may protect the seeds and facilitate their passage through the digestive tracts of animals (Tsou & Mori, 2002). Uses: Couroupita guianensis is widely planted in tropical and subtropical botanical gardens and as an ornamental throughout the tropics and subtropics; it does well under cultivation as far north as the Fairchild Tropical Botanical Gardens in Florida. Taxonomy: There is considerable variation in flower color and size as well as in fruit size and shape. Most fruits are globose and resemble a cannon ball, but some fruits are longer than wide.