Spathodea campanulata Beauv.
African tuliptree, Afrikanischer Tulpenbaum (German), Amapola, Apär, Baton du sorcier (French), Fa'apasi, Fireball, Flame of the Forest, Fountain tree, Indian Cedar, Ko'i'i, Mata ko'i'l, Mimi, Orsachel kui, Patiti vai, Pisse-pisse (French), Rarningobchey, Santo Domingo Mahogany, Taga mimi, Tiulipe, Tuhke dulip, Tulipan africano (Castilian), Tulipier du Gabon
The African Tuliptree (Spathodea campanulata) is native to tropical forests in a broad area of sub-Saharan Africa. However, it is now grown far more widely than this throughout the world's tropics and has been reported to be an invasive colonizer in the South Pacific (e.g., Tahiti and Rarotonga, Meyer 2004), Puerto Rico, and Brazil. (Bittencourt et al. 2003 and references therein). In Tahiti, for example, S. campanulata often dominates lowland mesic forests as well as native upland wet forests up to 1,200 m in elevation (Meyer 2004). It was first reported from the Pacific Islands (Hawaii) prior to the 20th century (Whistler 1995). These trees grow very rapidly (measured trees in Puerto Rico increased their trunk diameter by as much as 2 inches per year), but require nearly full sun (Little and Wadsworth 1964). Under good conditions, they may begin flowering as young as 3 or 4 years of age, with trees grown in the open flowering when they are about 5 m tall (Orwa et al. 2009).
Spathodea campanulata has large bright red flowers with the edges of the corolla lobes colored yellow ("corolla" is a collective term for all the petals in a flower). The flowering heads appear in circular masses with packed buds. The buds on the outer portion of the head open together, surrounding the inner buds. (Ayensu 1974)
The African Tuliptree (Spathodea campanulata) produces tubular tulip-like orange-red to scarlet flowers around 9 to 13 cm long and 7 to 8 cm across in erect clusters, mainly at the top of the tree's crown. Each flower has four pale yellow stamens 5 to 6 cm long with dark brown anthers. The flowers are subtended by a spathe-like calyx is covered with velvety rusty-brown hairs. The fruits are large erect green to dark brown pods around 13 to 25 cm long, 4 cm wide, and 2 cm thick, which point upwards at the ends of the branches. The oppositely arranged pinnate leaves are 30 to 60 cm long with usually 11 to 17 (sometimes 5 to 19) opposite elliptic 8 to 15 cm long leaflets on short stalks. The terminal inflorescenses (flower clusters) are around 10 to 25 cm long with the flowers clustered at the top. The fruit is an oblong capsule, 16 to 24 X 3.5 to 6 cm, which splits open to release numerous winged seeds, 2 to 2.5 cm long (including the membranous wings). The tree may reach 15 to 25 m in height and 30 to 45 cm in trunk diameter, with a dense irregular crown of large spreading branches that are evergreen or nearly deciduous. (Little and Wadsworth 1964; Whistler 1995)
The inflorescence of Spathodea campanulata includes around 40 to 50 flowers with acropetal maturation (i.e., the terminal flower is usually the first to mature, while the others tend to mature starting from the bottom of the stem). The showy orange ornithophilous (bird-pollinated) flowers have a flower fairly typical of the family Bignoniaceae, with a zygomorphic (bilaterally symmetrical) corolla, four didynamous stamens (i.e., 4 stamens in 2 pairs of unequal length), and a bicarpellate pistil with a 7.0 to 7.5 cm long style terminating in an exserted, bilamellate, touch-sensitive stigma. The ovary contains around 1000 ovules. (Bittencourt et al. 2003)
Spathodea campanulata has been a very successful invader in many regions to which it has been introduced. For example, together with Piper aduncum, it is the most successful woody invader of secondary forests in the northern New Guinea lowlands and adjacent Bismarck Archipelago. The tree invades early stages of rain forest succession developing in abandoned gardens from swidden (slash-and-burn) agriculture or after natural disturbance, such as the opening of large forest gaps from treefalls and landslides, but it does not penetrate into closed primary forests. (Bito 2007) Whistler (1995) writes that it escapes and becomes naturalized in disturbed lowland areas such as pastures and shrublands in Fiji, Samoa, Hawaii, Guam, and perhaps elsewhere in the Pacific Islands. However, Meyer (2004) reported that this species is indeed able to penetrate into apparently pristine undisturbed forests in the Society Islands in the eastern Pacific.
In its introduced range in the eastern Pacific, Spathodea campanulata grows in mesic-wet forests from 10 to 1200 m (Meyer 2004).
The African Tuliptree is an obligate outcrosser and requires pollinators for pollen flow between conspecific trees (Rangaiah et al. (2004). Bittencourt et al. (2003) carried out controlled pollinations of Spathodea campanulata in Brazil. Cross-pollination yielded 55% fruit set, whereas self-pollination resulted in no fruit set. Through careful embryological and histological investigations, Bittencourt et al. showed that the majority of ovules in selfed pistils were penetrated and fertilized within 48 hours, so the factors causing self-incompatibility and failure to set fruit are late-acting. According to Rangaiah et al. (2004), the natural fruit set of S. campanulata is very low, but is at least somewhat compensated for by a large seed crop.
Spathodea campanulata has winged seeds that are wind dispersed (Meyer 2004). The fruit is a capsule and dehisces naturally when mature, releasing small, light and winged seeds into the air. Seeds are dispersed efficiently by wind during the dry season. (Rangaiah et al. (2004)
Spathodea campanulata is frequently visited by nectar-feeding birds, which may be important pollinators (Corlett 2005). Rangaiah et al. (2004) found that birds were the exclusive pollinators of these flowers, based on their observations. They noted that bees also fed on the floral rewards, but they tended to feed on flowers from a single tree and therefore could not be effective pollinators given the self-incompatibility of S. campanulata. Trigona bees died in the calyx water and nectar and were consumed by visiting birds.
Ayensu (1974) reported that he had observed several bat visits to these flowers over several years in Ghana. He observed Micropteropus pusillus inserting their heads into the cup-like flowers to lap large quantities of rather dilute nectar. On several occasions, rather than enter the corolla tube, the bats tore the basal part of the flower cup, thereby obtaining an easy flow of nectar, which they lapped up. (Ayensu 1974)
Bito (2007) studied moth communities colonizing S. campanulata invading secondary rain forest vegetation in Melanesia. They found 54 species of folivorous Lepidoptera on S. campanulata. Most were generalists, feeding on more than just a single native plant family. However, the three most abundant species, representing 83% of all individuals (Acherontia lachesis, Hyblaea puera complex, and Psilogramma menephron) were relatively host-specific, feeding mainly on a single native family (native hosts: Rubiaceae, Verbenaceae, and Loganiaceae, respectively). Most of the 23 species analysed in detail had a wide geographic distribution, including 13 species wih distributions spanning the entire 1000 km study transect. Despite its phylogenetic isolation from the native vegetation, Spathodea campanulata was rapidly colonized (on a scale of decades) by folivorous Lepidoptera communities with a resulting species richness and dominance structure indistinguishable from the assemblages feeding on native hosts. Although most species were generalists, the highest population densities were reached by relatively specialized species, similar to the communities on native hosts. The species turnover across distances from 10 to 1000 km was relatively low as most of the species had wide geographic ranges.
Spathodea campanulata is used by humans mainly as a striking ornamental. Unopened flower buds contain water (foul smelling and tasting) which squirts out when the buds are squeezed or pricked and children play with them like water pistols. (Little and Wadsworth 1964)
According to Orwa et al. (2009), the seeds are edible and are used in many parts of Africa, but the hard central portion of the fruit is poisonous and used to kill animals.