Bullwood

The genus Sloanea is of the family Elaeocarpaceae, comprised of 150 species (Smith 1954, Steyermark 1988).Sloanea differs from other genera within Elaeocarpaceae in foliage, fruit, and basic number of floral parts, it has the basic number 4 whereas others genera have 3 (Smith 1954). Sloanea is distributed worldwide in tropical regions, with 70 of the total Sloanea species occurring in New World Tropics and 80 species in the Old World (Sampaio & Souza 2011). Sloanea are large canopy trees (Gentry 1993) and can be characterized by buttressed roots, simple and alternate leaves with a swollen petiole at the apex and base, flowers usually with corolla absent, and inflorescences with numerous stamens, usually with conspicuous connective prolongation and fruit capsule covered by flexible bristles (Sampaio & Souza 2014). Sloanea of the Old World have been separated into 3 subgenera, on the basis of petal type, whereas Smith (1954) separated New World tropical species into 2 subgenera on the basis of the condition of sepals in the bud.

All species of Sloanea are known to have an arboreal habit (Sampaio & Souza 2011; Coode 1983). Sloanea grows in tropical regions, mostly in lowlands and middle-elevation forests (Gentry 1993) and can be roughly divided into 3 categories; rainforest trees whose crowns are in the canopy, rainforest trees which make up a portion of the understory, and trees of drier forest or savannah areas with gallery forests (Smith 1954). Additionally, in the Neotropics, shrubby shoots from persistent root systems are to be expected from Sloanea when clearings have been made either along a watercourse or by agricultural activity (Smith 1954).

The center of diversification for the Old World species of Sloanea is in Malaysia, New Guinea, New Caledonia, and the area enclosed by Burma, Yunnan, Guangxi, Tonkin, and northern Thailand (Coode 1983). New world species have a center of diversification in northern South America and are distributed from southern Mexico to Brazil (Sampaio & Souza 2011). Species from Mexico to Ecuador are primarily found on the pacific side, and in the east side from Bolivia to southeast Brazil (Smith 1954). Central American species of Sloanea are most highly concentrated in Guatemala and southward through Costa Rica.

The genus Sloanea is of the family Elaeocarpaceae, comprised of 150 species (Smith 1954, Steyermark 1988).Sloanea differs from other genera within Elaeocarpaceae in foliage, fruit, and basic number of floral parts, it has the basic number 4 whereas others genera have 3 (Smith 1954). Sloanea is distributed worldwide in tropical regions, with 70 of the total Sloanea species occurring in New World Tropics and 80 species in the Old World (Sampaio & Souza 2011). Sloanea are large canopy trees (Gentry 1993) and can be characterized by buttressed roots, simple and alternate leaves with a swollen petiole at the apex and base, flowers usually with corolla absent, and inflorescences with numerous stamens, usually with conspicuous connective prolongation and fruit capsule covered by flexible bristles (Sampaio & Souza 2014). Sloanea of the Old World have been separated into 3 subgenera, on the basis of petal type, whereas Smith (1954) separated New World tropical species into 2 subgenera on the basis of the condition of sepals in the bud.

In the New World species of Sloanea, several trends of specialization have been observed, including a trends toward a reduction of the inflorescence, modification of the inflorescence, a development of specialized capsular spines, and a trend towards the development of large, persistent stipules (Smith 1954).

Sloanea is ecologically important, some species are an important food source for endangered species like parrots. Many species of Sloanea are endemics, and most of them are rare and large canopy trees whose wood is generally hard and dense. In the Amazon basin and Asia people are destroying primary forests in part for Sloanea wood for production of materials (IUCN 2015).

IUCN red List of Threatened Species

Sloanea gracilis

Range: An endemic to Brownsberg. Native to Suriname.

Vulnerable

Sloanea acutiflora

Range: Locally abundant in places. It is endemic to Brownsberg and the Tapanahony River. Native to Suriname.

Vulnerable

Sloanea lepida

Range: Oua Némi and Mé Oué in the north of Grand Terre. Native to New Caledonia.

Vulnerable

Sloanea shankii

Range: A rarely collected species. Nativeto Honduras.

Critically Endangered

Sloanea tomentosa

Countries: Bhutan; China, India, Myanmar, Nepal, Thailand.

Lower risk/least concern

Sloanea assamica

Native: Bhutan, China, India, Myanmar.

Lower risk/ least concern.

Sloanea suaveolens

Range: a species which appears to be known from a single location on Mt. Tonine. Native to New Caledonia

Vulnerable

New World:

In the New World species of Sloanea, inflorescences are paniculate or racemeose, but numerous variations occur. The inflorescences are generally borne on the axil of a leaf or leaf scar. Most New World species bear 5 or more flowers per inflorescence. In most, the pedicels, peduncles, and persistent bracts are pubescent. Essential organs consist of a compound pistil with 3 to 6 locules and innumerable stamens borne on the same flower (Smith 1954). The sepals of New World Sloanea species are of particular importance as they are the basis for separating the America species into two subgenera: Sloanea and Quadrisepala. New World species of Sloanea are vastly apetalous (Coode 1983). Some Sloanea species have flowers that show the “buzz pollination” syndrome, suggesting they must be pollinated by bees (Matthews and Endress 2002).

Old World:

In Old World species of Sloanea, flowers are in most species, if not all, open long before their floral parts have reached a mature length. There is one distinctive form of inflorescence that is identified; however, two other less distinctive forms (seen in S. javanica) exist. Inflorescences, therefore, generally consist of solitary axillary flowers that are grouped terminally. Pedicels may be condensed to lateral, few flowered racemes. Buds that are terminal and apparently vegetative are present in many species with flowers in short racemes. Stamens are numerous, from 50 to 200, and filaments are short or absent, but always hairy. Anthers are incurved or straight that open by slits and later extend downwards (Coode 1983). Petals are of particular importance because they place Old World Sloanea species into 3 subgenera; sepaloid petals differing only in length from the sepals; petals clearly different from sepals, thinner, fused or free, and mostly toothed at the apex; and petals absent (Coode 1983). Old world species of Sloanea also commonly exhibit buzz pollination syndrome (Matthews and Endress 2002).

New World:

Fruits in New World species of Sloanea are in the form of dehiscent capsules, which may be ellipsoild, ovid, or globose. Dehiscence is generally from the apex with capsules opening only far enough that seeds stay disclosed, though some species form valves that are completely reflexed. Nearly all Sloanea have capsular fruits covered in long, twisting, or curving spines (Coode 1983). Spines appear among the hairs clothing the ovary soon after development and then grow rapidly as the fruit approaches maturity.Armed capsules that are borne by the majority of Sloanea species are ornamented with small irritant, soft, or stout spines. Each capsule in New World species bears only 1 to 2 seeds, though there may be the occasional three. Additionally, seeds usually contain a thick and fleshy aril that is orange in color to attract their disperser (Smith 1954). Dispersers are generally birds. However, some parrots and other birds may be seed predators, such as the Great Green Macaw.

Old World:

Fruit in Old World species of Sloanea are also woody and dehiscent. Though in some species valves may not fully develop and therefore remain undehiscent, fruit are generally 2-5 valved. As in New World species, most valves part so that they form 90-degree angles, though some open widely and completely detach. The outer surface may bear spines that can be simple, broad-based, variously glabrous, or soft, and of numerous lengths. Spineless fruits are less common. Styles are short to long and often are twisted or fluted. There are two basic seed types. In one seed type, the apex of the seed always gives rise to a thick or fleshy aril. This aril usually grows to cover more of the seed than merely the attachment point. This seed type, which is almost universal in South America, is also common in the Old World. The second seed type has a completely enveloping sacrotesta, which is fused to the seed coat or virtually all over it. Inner seed coat thickness varies (Coode 1983).

All species of Sloanea are trees, mostly large and some small, and they may flower while still shrubs (Coode 1983). Sloanea have simple, alternate leaves. A good character for the genus is the bitumid petiole, meaning it is swollen at the both ends (Condit et al. 2011, Sampaio & Souza 2014). Leaf venation can be pinnate, commonly with secondary straight in small leaves and curved in larger leaves, though venation may also be simple. Leaf margins vary from entirely to sharply dentate (Smith 1954). Few species show leaves crowned toward the ends of twigs (S. rufa, S. grandulosa, S. brevipes, S. spathulata, S.ligulata) (Smith 1954). Some species can have large stipules that look like leaves (e.g. S. ligulata).

Sloanea is a genus of flowering plants in the family Elaeocarpaceae, comprising about 150 species.

Species include:

Sloanea acutiflora Uittien Sloanea assamica Rehder & E. Wilson Sloanea australis Benth. & F.Muell., an Australian rainforest tree Sloanea berteroana Choisy ex DC. Sloanea caribaea Krug & Urb. ex Duss Sloanea gracilis Uittien Sloanea lepida Tirel Sloanea shankii Standl. & L.O.Williams Sloanea suaveolens Tirel Sloanea tomentosa Rehder & E. Wilson Sloanea woollsii F.Muell., an Australian rainforest tree