The Caribbean tree Hibiscus elatus, known as blue mahoe or majagua, is a highly valued, fast-growing timber species that has adapted to a wide range of sites and is often used in reforestation. It produces excellent timber for high-grade furniture, but can also be used as a windbreak. Ease of germination results in successful plantation establishment. It could be grown on a larger scale as a plantation crop but suffers from epicormic branching and sweep. H. elatus is also grown for ornamental and shade purposes and is the national tree of Jamaica.
H. elatus commonly grows to a height of 20–25 m and a diameter of 30–45 cm, although on fertile sites it may reach a diameter of 90 cm. The bole is straight and long. The bark is soft in texture and consists of many layers that can be separated after beating.
The leaves are broad, simple, entire or lightly toothed, and arranged spirally. The petiole is up to 14 cm long, slender, greenish and densely covered with white hairs. The blade is cordate, up to 20 × 20 cm in size, acuminate at the apex, and palmately 7–9 nerved at the base. The nerves are depressed above and raised below. The blade is glabrous above and densely whitish-haired below.
Typical hibiscus-like flowers are borne in terminal panicles or laterally near the end of twigs. They are trumpet shaped, 7.5–10 cm long and 8–13 cm broad, with yellow petals that change colour as they mature to orange, red, and finally crimson. The calyx is tubular with five narrow pointed lobes. Flowers last 1 day and flowering occurs irregularly throughout the year.
Fruits are grey-green, hairy capsules, 2.5–3 cm long, containing numerous blackish-brown seeds.
H. elatus is native to Cuba and Jamaica. It has been widely planted on both islands and has naturalized in southern Florida (USA), Mexico, Peru, Brazil and throughout the West Indies.
H. elatus is a fast-growing timber species that can adapt to a wide variety of sites. Drought can be a limiting factor on well-drained sites where annual rainfall is less than 1500 mm; even so, it will survive on alluvial plains receiving an annual rainfall of 1000 mm or less. In wetter areas with annual rainfall ranging from 1500 to 3800 mm it will grow under a wide range of soil conditions and at altitudes of up to 1200 m. H. elatus grows best near mountain bases and on lower mountain slopes. It performs poorly on shallow soils over bedrock, on very poorly drained soils and on severely eroded or nutrient-depleted sites, but tolerates acid clay soils. It is intolerant of exposed conditions, such as on exposed ridges. It suffers from epicormic branching and sweep.
In the West Indies, seeds ripen in March and April when the capsules are picked and laid in the sun to dry. Seed weight averages 1.8–1.9 g/100 seeds in Jamaica but slightly less in Puerto Rico. Germination percentage is high in Jamaica (80%), but poor in Puerto Rico. H. elatus can also be propagated by cuttings, grafting and tissue culture.
Seedlings can be transplanted after 1 year when they range in height from 45 to 60 cm, and rapid growth commences about 6 months after outplanting.
In order to avoid the development of epicormic branches, planting densities of at least 2.5 × 2.5 m and thinning to 3.5 × 3.5 m in mature plantations are recommended.
The volume of stands aged from 16 to 27 years ranges from 97 to 979 m3/ha, and mean annual increment ranges from 4.5 to 36 m3/ha.
H. elatus is relatively free from diseases and pests, and there are only occasional reports of damage. In Jamaica, fungal leaf spots caused by species of Septoria and by Pestalotia heterocornis have been recorded, while in Cuba, leaf spots caused by bacteria have been observed.
Anomis illita is an important defoliator. H. elatus is also a host to cotton stainers (Desdercus spp.) and to the pink hibiscus mealybug (Maconellicoccus hirsutus).
H. elatus is often planted as an ornamental and shade tree, and can also be used as a windbreak, despite its tendency to lose leaves during dry spells and susceptibility to limb breakage. The species has shown promise when used in agroforestry trials in Cuba.
The fairly straight grain of H. elatus heartwood is richly variegated with shades of steely-blues, metal-greys, deep purples, olive-greens, and browns, with an elegant chatoyance in the wood. The narrow sapwood is pale white and subtly flecked, creating an attractive contrast with the heartwood. The wood is hard, elastic, very durable, highly resistant to attack by decay fungi, and resistant to subterranean termites. It has a basic specific gravity (oven dry weight/green volume) of 0.58 to 0.62, while the average density has been recorded as 500 kg/m3. The timber works easily and is generally easy to saw, plane, rout, mould, mortise, carve, glue, nail, screw, sand and turn, with a natural gloss in the wood when finely finished. It responds very well to both hand and machine tools in all woodworking operations.
The wood is used for high-quality furniture, house interior trim and craft items, and various other purposes including light construction, railway sleepers, containers, agricultural implements, turnery, musical instruments, flooring, inlays, carvings and boatbuilding.
The inner bark of young trees is used for making rope and cords, which are reported to be very durable in salt and brackish water.
The mucilaginous young leaves and twigs are traditionally used to treat dysentery, and when boiled with Cissus sicyoides can be used to treat colds.
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