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Homalanthus populifolius

Native Bleeding Heart, Native Poplar

Family: Euphorbiaceae

A small tree or shrub, up to 8 meters tall with a rounded spreading canopy to several metres wide.

It occurs commonly in NSW, along the entire coastal fringe and parts of the coastal inland, extending west to areas such as the Hunter Valley (Merriwa-Scone), Mt Kaputar National Park near Narrabri. It extends into Queensland, along the coast and parts of the inland to Cooktown. In Victoria, it is thought to be a weed, found in disturbed sites in north-eastern Victoria and around Melbourne and Port Phillip Bay. It is native to New Guinea and the Pacific Islands. It is a serious weed in New Zealand and also a weed in Western Australia. 

It is known to be a common species in rainforest margins and disturbed patches of wet and dry sclerophyll woodlands in some areas. It is a “pioneer” species; a species that regenerates rapidly following disturbance, in either rainforest or other habitats. It is a species that can be found in degraded vegetation patches such as around landfill and industrial sites and road batters. It can also appear en masse when large infestations of weeds are removed in bushland (such as privet infestations), especially on Hawkesbury Sandstone locations in Sydney. 

The trunk is cylindrical with greyish-brown bark, fairly smooth but with some bumps and irregularities, and up to 15 cm in diameter. The branchlets appear thick, reddish or green and exude a milky sap when broken, as do the petioles of leaves. 

Homalanthus spp. have simple and alternate leaves. In this species, leaves are conspicuous and easily recognised: triangular (deltoid) to heart shaped (cordate) or ovate, to 15 cm long and 12 cm wide, with entire margins, mid to dark green above with fine veins and a pale grey to white below, on petioles to 12 cm long; through the year, leaves can turn to shades or purple / red or red-orange as they age, which can create a showy appearance. As trees age and grow, the foliage tends to get smaller. 

Homalanthus spp. often produce separate male and female (unisexual) flowers but on the one plant and even on the one inflorescence (monoecious); arranged in terminal racemes appearing like catkins which hang down; to 10 cm long by about 0.5 cm wide. In this species, individual flowers are very small with the racemes consisting mostly of male flowers which have many stamens; female flowers are at the base of the inflorescence; produced in the months of September to December.  

The fruit of Homalanthus spp. is a capsule. In this species, they are glaucous and two-lobed, to 10 mm wide and smooth, ripening in late summer. 

In the garden

The small size and decorative red leaves make this an attractive garden plant although it is not widely used in horticultural applications. 

It has been used to great effect by some native landscapers, especially when pruned and allowed to reach its full size. In such cases, it can serve as a similar plant to something like a Japanese Maple or Chinese Tallowwood (the latter a very similar-looking plant) (see images in resources below). 

It is often short lived and the flowers are not very showy; hence it will often be overlooked for nicer plants. However, if pruned and cared for, it can provide a nice contrast in the garden.

Many years ago, this plant often came up naturally in the author’s northern Sydney garden from seeds dropped by birds. Over time, bird life has been reduced and this garden is now much drier with the result that the plant has been lost. This is a pity, as they make a good feature plant.

Editor’s note: I also have one plant which came up of its own accord after much Fishbone Fern was weeded out of a Sydney sandstone garden. I am pruning and shaping it. 

The characteristics as a pioneer species also make it an invader in disturbed areas. It is now a recorded weed in some areas – so consider the planting location. 

It can make a very nice feature plant. Check with bushcare and other native nurseries for availability.

Be careful when pruning and plants exude a white milky sap. 

Tolerates a range of soils as well as shade to full sun. 

Propagation

The seeds germinate quickly when the warmth of direct sunlight is available. However, as with many pioneer species, the seeds have a long dormancy period.

Other information

Much confusion was caused when this plant was renamed from Omalanthus populifolius to Homalanthus populifolius – which hinged on an error, rooted in Greek, concerning the missing ‘H’. This correction was made as early as 1828 but was inconsistently applied. The species was also changed to H. nutans for a time but was then changed back again to this species. H. nutans is considered to be a different species.

This plant regenerates rapidly after fire where seed is present and will also regenerate after any sort of disturbance if propagules are present. 

Homalanthus is a genus of about 35 species, occurring in Polynesia, Malesia and Australia. Australia has 3 species. NSW currently has 2 species. 

Homalanthus from Greek Omalos (ὁμαλός) meaning “even”, “level” or “equal” (not “smooth” as reported by some websites and texts) and anthos (ἄνθος) meaning “flowers – referring to the highly equal-length flowers of some species.

populifoliusLatin – with leaves similar to the Populus (Poplar) genus.

This species is not considered to be at risk of extinction in the wild. 

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

Hornsby Shire Council – Homalanthus populifolius factsheet https://www.hornsby.nsw.gov.au/_resources/documents/environment/idigenous-trees/Fact-sheet-Homalanthus-populifolius-Bleeding-Heart-Tree.pdf

H. Esser (Hans-Joachim) (1997). A revision of Omalanthus (Euphorbiaceae) in Malesia Blumea: Biodiversity, Evolution and Biogeography of Plants , Volume 42 – Issue 2 p. 421- 466

Mallee Design – Homalanthus populifolius information page:       https://malleedesign.com.au/extremely-fast-growing-screen/ 

By Dan Clarke and Jeff Howes.