Melaleuca pentagona is a medium shrub that grows to 3 metres tall, spreading to 2 metres wide.
It is another melaleuca endemic to the south-west of Western Australia, growing mostly along the south coast; from around the Denmark-region, east to Nuytsland Nature Reserve, north to about 50 km inland (north of Ravensthorpe).
It is often found on gravelly sands, loams and clays, in shrubland, heathland and dry sclerophyll woodland.
Melaleuca spp. can present with simple and alternate or opposite leaves. In this species, leaves are alternate and somewhat spiraled around the stem, to about 20 mm long by 5 mm wide, linear to narrow-elliptical, with an upper groove; light to mid-green in colour.
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 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). Melaleuca flowers do not have pedicels (sessile).
In this species, up to around 25 staminate flowers (in groups of 3) are produced in globular heads, to 20 mm diameter, carried on the ends of branches and in leaf bases; pink to purplish in colour; each flower about 4 mm wide by 10 mm long; appearring in spring.
The fruit is a capsule, that are to around 3 mm wide, often with 5 angled sides (pentagon), produced in an attractive globular cluster to 20 mm wide.
Melaleuca pentagona is a medium shrub that has reached a height of three metres in our cold climate garden (near Armidale, NSW)
Many of these melaleucas, including M. pentagona, are virtually unknown in cultivation but have great horticultural potential.
This species is known to be cultivated, perhaps with more limited success compared to other species from WA outside of their natural range.
It is best grown in full sun on a sandy and well-drained soil.
Blooms are both conspicuous and profuse. This can be a very attractive shrub. Prune lightly after flowering.
Propagate from seed or cuttings that produce roots rapidly and readily.
This species can regenerate well after fire through epicormic shoots and basal coppicing as well as form the seed bank.
The genus Melelauca 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 all Callistemon spp. 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.
Melaleuca is a genus of about 220 species, occurring mostly in Australia, but also Malesia and New Guinea. Australia has about 215 species with 210 reported endemic, occurring in all states. NSW currently has 30 species.
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.
pentagona – Greek – pente (πέντε) meaning “five” and gonia (γωνία) “angled” – meaning a pentagon – referring to the appearance of the fruit.
This species is not considered to be at risk of extinction in the wild.
Western Australian Herbarium (1998–). Florabase: The Western Australian Flora – Melaleuca pentagona profile page https://florabase.dbca.wa.gov.au/browse/profile/5948
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.
Wikipedia – Melaleuca pentagona profile page https://en.wikipedia.org/wiki/Melaleuca_pentagona