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Melaleuca biconvexa

Family: Myrtaceae

A shrub or small tree, up to 10 metres tall, though occasionally as high as 20 metres. It has typical paperbark.

It is found only NSW, with scattered and dispersed populations found in the Jervis Bay area (Tomerong, Callala Bay, Vincentia) and then north in the Gosford-Wyong area with additional records towards Port Macquarie.
It is a listed threatened species.

It grows in damp places, often near streams or low-lying areas, on alluvial to sandy soils in dry sclerophyll swamp forest. Populations are usually clonal with many stems coming off the same rootstock.

Leaves are opposite, broad to narrow-ovate, to 18 mm long and to 4 mm wide with 3 distinct veins; each leaf has a centre-vein in a groove and the leaf blade curves upwards on either side of this centre-vein. Leaf placement is distinctive, with each pair of leaves emerging at right angles to the following and preceeding pair (decussate).

In Melaleuca species, flowers are usually arranged in spikes or heads. Within the head or spike, the flowers are often in groups of two or three, Flowers have five sepals (sometimes fused into a ring of tissue) and five petals which are typically small and do not persist on the flower for long.

Like many other Myrtaceae genera, the flowers are conspicuously staminate and without a petiole (sessile) with each flower having many stamens surrounding one carpel. The stamens are typically fused into five separate bundles (staminal claws) which each bundle sitting opposite a petal (a generally useful identifying feature for the genus to distinguish it from Callistemon).

This species has dense heads to short spikes about 1 cm long, flowers sit individually within the head, white or pale yellow with petals to 5 mm long. The staminal claws have about stamens.

The capsule is urn-shaped, to 5 mm in diameter and the orifice to 3 mm in diameter with sepals persistent.

In the garden

Not much is known about the cultivation potential of this species as it is a threatened species.
It may be available for cultivation in the future.

Melaleucas are mostly pollinated by insects, including the introduced honey bee (Apis mellifera), flies, beetles, wasps and thrips. Birds such as lorikeets and honeyeaters, as well as, flying foxes often visit the flowers and are probably also pollinators. Hence, they are important plants to create diversity in a suburban garden.

Most species respond well to pruning. It is advised to undertake a light annual trim to promote bushy growth. Some will withstand severe pruning as they can produce coppicing growth (epicormic shoots etc).

Melaleucas are typically healthy plants and can usually defend against pests and diseases. The most serious pest is probably webbing caterpillar. These grubs will encase themselves in a web-like structure of foliage and droppings, causing severe defoliation.

Melaleucas can be fertilised if done responsibly. The use of a slow-release fertiliser after flowering is recommended.

Propagation

Melaleucas can be propagated by either seed or cuttings. However, to maintain desirable characteristics of a particular plant, vegetative propagation (eg. cuttings) must be used. This also applies to propagation of named cultivars.

Other information

The name M. pauciflora was misapplied to this taxon for many years.

The genus Melaleuca has been subject to recent taxonomic revision with early and recent botanists including Ferdinand von Mueller and Lyndley Craven (deceased in 2014) proposing to expand the genus to include Callistemon and others.

Craven et al. (2014) published new species combinations which included the renaming of all Callistemon species to Melaleuca, based on evolutionary relationships and DNA evidence and other features.

Currently, the NSW Herbarium advises that the Callistemon genus can still be used.

A link showing the differences between Melaleucas and Callistemons is here: http://anpsa.org.au/mel-cal.html

Resprouts following fire with basal coppicing growth and branch shoots.

Melaleuca – is derived from the Ancient Greek mélas (μέλας) meaning “dark” or “black” and leukós (λευκός) meaning “white”, apparently because one of the first specimens described had fire-blackened white bark.
biconvexa – is from the Latin bi- meaning “two” and convexus, “convex”, in reference to the shape of the leaves in cross section, where each side is convex.

This species is threatened with extinction in the wild at both the State and Commonwealth level, with the category of vulnerable.

NSW Office of Environment and Heritage – Threatened Species Profile Page – Melaleuca biconvexa
https://www.environment.nsw.gov.au/ThreatenedSpeciesApp/profile.aspx?id=10514

NSW Flora Online (PlantNET) – Melaleuca biconvexa profile page
https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Melaleuca~biconvexa

Wikipedia – Melaleuca biconvexa and Melaleuca profile page
https://en.wikipedia.org/wiki/Melaleuca_biconvexa
https://en.wikipedia.org/wiki/Melaleuca

By Jeff Howes, edited Dan Clarke