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Lumnitzera racemosa Willd. 1803
pronounced: lum-NITZ-uh-ruh rass-ee-MOH-suh
(Combretaceae — the false almond family)
common name: White-flowered Black Mangrove
Lumnitzera is named for Stephen Lumnitzer (1750-1806), a physician who published Flora Posiensis in 1791. This book describes the flora of Bratislava, the capital of Slovenkia, and its wider precincts, listing 1574 species. Racemosa is from the Latin racemosus, meaning ‘full of clusters’, referring to the fact that the inflorescences of this species are racemes.
There are two species of the Black Mangrove. Lumnitzera littorea grows only to about 3 m tall in North Queensland, and is found only as far south as the Hinchinbrook Channel. It has red flowers. Our species grows to twice that height. This evergreen, medium-sized, erect and much-branched tree, is usually found growing on the landward edge of the mangroves, and most often in small, isolated clumps. Above-ground breathing roots are normally absent, but in very moist environments small looping lateral roots may develop. The trees photographed are in Geoffrey Bay, near the road to the old jetty. There are also some growing in the creek near the jetty in Picnic Bay.
The bark is dark grey, and fissured longitudinally in older trees. The leaves are simple, alternate in arrangement, and reasonably small, 3–7 cm long and 2–3 cm wide. They are succulent, obovate in shape with an indent in the tip. The inflorescence is a spike, 2–3 cm long and axillary in position. The flowers are small, about 1 cm in diameter, and erect with a green-coloured tube-like calyx divided into five lobes at the tip. The five petals are white. The fruit is vase-shaped, 1–2 cm long, yellowish green in colour, glossy, corky, buoyant, and dispersed by current. Each fruit contains one ovoid-oblong seed.
Most mangroves reproduce themselves by a process called vivipary, the condition whereby the embryo (the young plant within the seed) grows first to break through the seed coat then out of the fruit wall while still attached to the parent plant. Some use cryptovivipary (Greek κρυπτος, kryptos, hidden), the condition whereby the embryo grows to break through the seed coat but not the fruit wall before it splits open. There is intense speculation as to why so many mangrove species demonstrate vivipary or cryptovivipary; but the Black Mangrove uses neither.
In some areas, the wood of this mangrove is used for a variety of purposes, being hard and durable. In the Maldives, it is used for house construction, with sticks of lesser diameter being used for rafters in the roof. Larger wood is sometimes used for boat-building. Stems are used for poling boats along in shallow water. It is considered an excellent firewood, and high-quality charcoal is produced from larger stems.
Caterpillars of the Copper Jewel Butterfly Hypochrysops apelles feed on this plant.
Photographs taken at Geoffrey Bay 2012 and Horseshoe Bay 2013
Page last updated 23rd January 2018