Bleeding Heart

Homalanthus novo-guineensis (Warb.) Lauterb. & K.Schum.

Synonyms - Homalanthus nutans, Homalanthus populifolius, Omalanthus nutans, Omalanthus populifolius.

Family: Euphorbiaceae

Names:

Other Names:

Bleeding Heart, Mouse Deer's Poplar, Native Bleeding Heart, Native Poplar, Queensland Poplar, Tropical Bleeding Heart.

Summary:

Bleeding heart is a fast growing shrub or small tree to 12 m high. The leaves are long-stalked, triangular to diamond shaped with a long-pointed tip, 5-23 cm long, greyish green in colour but turning red with age. The tiny unisexual flowers are arranged in a long yellowish green spike which may be up to 13 cm long. The female flowers are at the base of the spike and the male flowers towards the tip. The fruits are bluish globular capsules. All parts have white, sticky latex.
Bleeding Heart is native to tropical Australia, including the Kimberley, but planted as an ornamental and has now become a weed of wetlands and creeks. It flowers in mainly in May to June.

Description:

Cotyledons:

Two cotyledons narrowly obovate-oblong, about 7-10 x 2 mm.

First leaves:

First pair of leaves kidney shaped to almost orbicular. At least some leaves usually peltate before the 10th leaf stage. At the tenth leaf stage: leaf blade is cordate, apex broadly obtuse or rounded, upper surface glabrous, under surface somewhat glaucous; two glands visible on the underside of the leaf blade near its junction with the petiole; several small flat glands occur on the underside of the leaf blade on lateral veins towards the margins; stipules sheathing, large and conspicuous, ovate, about 10-15 mm long, caducous.

Leaves:

Alternate, simple with white, sticky latex. One or two cup-shaped glands are on the upper surface of the leaf blade at its junction with the petiole. The glands are frequently pink or red inside.
Stipules - Large, 7-20 mm long and conspicuous but fall early. Cuneate at base, margin entire, truncate to acute at apex, with distinct parallel venation, enclosing buds of leaves and inflorescences
Petiole - 20-130 mm long, glabrous to covered with fine white hairs (puberulous), glandless.
Blade - Symmetric, triangular to diamond shaped with a long-pointed tip, 50-230 mm long x 35-100 mm wide. Greyish green in colour and much paler on the underside. They turn red with age just before falling.
Orbiculate to ovate to elliptic, 45-190 by 35-160 mm, index 0.8-1.7, base cuneate to rounded to slightly emarginate, peltate (up to 3 mm) or not, apex acute to acuminate, lower surface whitish but most of venation of different colour, glabrous to puberulous, side veins in 9-13 pairs below the apex, angle of divergence 45-55°, hardly joined towards the margin, tertiary veins percurrent (extend the whole length), quaternary veins reticulate, adaxially on junction lamina base/petiole with an undivided, disc-shaped, prominent gland 1-2 mm in diameter, glandless only when base peltate, abaxially usually with a pair of glands near base, 0.25-1.25 mm in diameter and 1-15 mm distant from petiole apex, additionally with 0-3 glands on each half of blade, 0.3-0.4 mm in diameter and 3-5 mm distant from leaf margin, rarely completely glandless abaxially. Margin entire. Tertiary veins always distinct

Stems:

2-12 m tall usually up to 25 m tall. Rarely more than 300 mm diameter at breast height (dbh) up to 50 cm. Straight, much-branched and with umbrella-shaped crown; without buttresses. Glabrous to yellowish-brownish puberulous. Bark glabrous to puberulous, about 5 mm thick, medium tan to creamy-white to grey, finely vertically fissured, with round pustular lenticels; under bark light green; inner bark straw to brown to purple-brown.
Bark smooth.
White to straw, soft wood.
White, sticky latex.

Flower head:

Tiny flowers are arranged in a long yellowish green terminal spike which may be up to 130 mm long. The female flowers are at the base of the spike and the male flowers towards the tip.
50-130 mm long, sometimes bisexual and then pistillate part as long as or longer than staminate part, but quite often only with staminate or only with pistillate flowers, staminate part 5-7 mm in diameter, glabrous to puberulous. Bracts of staminate clusters pf flowers (cymules) 0.9-1.25 mm long, at base with a cluster of foveolate to cup-shaped glands with shiny centre and thickened, glaucous-papillate margin, 0.75-1.5 mm long and consisting of at least 6 single glands 0.2-0.4 mm in diameter, distinctly (by 0.4-0.8 mm) overtopped by the bract.

Flowers:

Yellow green, tiny, unisexual.
Both male and female flowers laterally compressed, about 1-1.5 mm diameter Cerebriform glands present on the inflorescence axis at the base of each pedicel.
Staminate flowers 3(1-6) per cymule; pedicel 1-2.5 mm long;
Pistillate flowers 8-30 per thyrse if not absent at all; pedicel 2-10 mm long;
Ovary - 1-2 mm long, bicarpellate, papillate, style 0.2-1 mm long, stigma about 1-2 by 0.3-0.5 mm, undivided, with a minute apical gland (up to 0.5 mm long) or rarely glandless. 2 or 3-locular, without excrescences, mostly papillate to puberulous, each locule with 1 anatropous ovule
Sepals - 2, about 0.5-0.7 mm long in staminate flowers. About 1 mm long in pistillate flowers
Petals - corolla, disc, and nectaries absent
Stamens - 6-8 per flower, with filaments about 0.3 mm long and anthers 0.3-0.4 mm long. Free, usually covered with dense papillae, filaments present, nearly as long as anthers, hardly elongating at anthesis.
Anthers - dorsifixed, opening latro-extrorsely with longitudinal slits, connective present.

Fruit:

The fruits are bluish globular capsules but laterally compressed, about 8-9 x 8-9 mm. Woody schizocarp. 2 or 3-seeded sometimes with only 1 seed developed.
Stigmas persistent at the apex, pedicels about 15-20 mm long, slender. Aril very oily.
2-30 per infructescence; bract persistent; pedicel 0.8-3.5 cm long; calyx caducous; fruit excluding style 5-13 by 6-9 mm, papillate, distinctly to indistinctly sulcate, not to slightly carinate, style persistent, fruits often one-seeded and then with lateral, oblique style; regularly opened fruits not uncommon, pericarp 0.2--0.25 mm thick (i.e. 1:30 of fruit length), remaining columella 5 by 1 mm, slightly alate.

Seeds:

Around 4.5-5 by 2.5-4-4 mm, elliptical. Testa reddish to brownish, smooth, hard but brittle, not shining, fibres radial. Apically or over its whole length covered by pale to whitish, membranaceus arillode.

Roots:

Taproot with many secondary roots.

Key Characters:

Heart shaped leave that turn red with age before falling.
Leaf blade whitish beneath or not, with either abaxially completely visible venation, or only larger veins distinct; abaxial laminar glands, if present, between midvein and margin or closer to margin. Petiolar glands absent or lateral to abaxial
Leaves without abaxial to lateral petiolar glands.
Leaves on the upper side with one (or two) prominent, cup- to disc-shaped glands at junction lamina base/petiole apex.
Bract glands not elevated, touching rachis.
Bract glands in many, at least 4, pairs, each gland cup-shaped with shiny centre and paler, glaucous-papillate, usually elevated margin. Fruits 2-30 per infructescence. Plant glabrous or puberulous.
Stigma usually not conspicuously wider at base.
Stigmatic glands very short, covering less than a quarter of the length of the stigma, or absent.
Style and stigma not very soon caducous, often found on ripe fruits. Fruits (3.5)5-14 mm long, sulcate or not. Leaves apically mucronate to cuspidate; petiolar glands absent or regularly rounded, disc or cup-shaped.
Stigma not glandular over its whole length, more than 0.5 mm glandless.
Stigma not or, rarely, only apically divided. Fruit elliptical to slightly obovoid in shape, without a conspicuous, narrow base.
Leaves adaxially with one or two elevated glands at junction blade/petiole.
Stigmatic glands very short, covering less than a quarter of the length of the stigma, or absent.

Biology:

Life cycle:

Perennial.

Physiology:

Water logging tolerant.

Reproduction:

By seed.

Flowering times:

Mainly May to June.
Flowers and fruits have been collected all year round.

Seed Biology and Germination:

Vegetative Propagules:

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread by water and birds.

Origin and History:

Native to tropical Australia including the Kimberley.

Distribution:

ACT, NSW, NT, QLD, SA, TAS, VIC, WA.

Courtesy Australia's Virtual Herbarium.
N and NW Australia (West Australia, Northern Territory, Queensland) and in Malaysia: Lesser Sunda Islands (eastern part), Maluku Islands or Moluccas, New Guinea, Solomon Islands.

Habitats:

Edges of waterways and seepage areas. Often in waterlogged areas.
Altitude 10-2,300 m

Climate:

Mainly sub tropical.

Soil:

Sandy loam, clay.
Old coral limestone, well-drained volcanic soil, dark marshy soil, rocky alluvium, poorly drained consolidated alluvium, clayey soil on limestone, alluvial sandy clay.

Plant Associations:

Significance:

Beneficial:

Planted as an ornamental.
The sap of young leaves is administered to young children as mild laxative (Heyne, 1950). Leaves and bark are used as black dye (Heyne, 1950). The leaves are used for wrapping food, the wood as firewood, and for construction.

Detrimental:

A weed of wetlands and creeks.

Toxicity:

Suspected of being toxic in the Kimberley region of WA (516 )
The latex is poisonous and harmful to the eyes.

Symptoms:

Treatment:

Remove stock from the infestation.

Legislation:

Management and Control:

Grub out seedlings.
Spraying the leaves with 1 g metsulfuron600 plus 100 mL spray oil in 10 L water normally provides good control (In NZ they use 5 g metsulfuron per 10 L water). It is expected that seedlings may emerge for a few years and these may be sprayed or removed manually using protective clothing to prevent skin contact.
Cut and paint stumps of larger plants with Vigilant® (picloram) gel.
Large plants can be manually removed but care needs to be taken to prevent contact with the milky sap.
Basal bark treatments with triclopyr or Access® in diesel can also be tried.

Thresholds:

Eradication strategies:

Repeat the management options above.

Herbicide resistance:

None reported.

Biological Control:

Related plants:

Homalanthus populifolius is very close to H. novo-guineensis. Both are the only species of the genus where multiple bract glands may occur, and leaves, flowers, and fruits are hardly distinguishable. The stigma length, used repeatedly by Airy Shaw, does not separate both taxa. Interestingly, he first (1968) did not see a difference in this character, whereas he later (1981) distinguished H. populifolius by elongate stigmata. This character is as variable in H. populifolius as in most other species. Only two herbarium characters remain for separation from H. novo-guineensis, the number of bract glands (1-3 pairs against usually at least 6 pairs), and their morphology (roundish pillow-shaped with uniform surface against cup-shaped to foveolate with papillate margin and shiny centre). Additionally, H. novo-guineensis sometimes is puberulous, contrary to H. populifolius, the number of pistillate flowers per thyrse is usually much higher in H. novo-guineensis, and inflorescences are more often unisexual in the latter; but these last characters are not always visible. The limits of both species remain somewhat vague, and field studies may be necessary to evaluate the reliability of these features. Airy Shaw (1968) suspected introgression. The hairy-papillate ovary surface, used by Forster (1994), does not distinguish both. Contrary to the repeated confusion with H. populneus (compare the literature citations under both taxa!) and remarks like those of Airy Shaw (1968), this species does not seem to resemble H. populifolius closely.
Omalanthus populifolius does not occur in WA.

Plants of similar appearance:

References:

Bodkin, F. (1986). Encyclopaedia Botanica. (Angus and Robertson, Australia).

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra).

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne).

Esser, H.-J. 1997. A revision of Omalanthus (Euphorbiaceae) in Malesia. Blumea 42: 421-466.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney).

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P132.

Harden, Gwen J. (1991). Flora of NSW. (Royal Botanic Gardens, Sydney). Volume . P. Diagram.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (2007). Western Weeds. A guide to the weeds of Western Australia. (Second Edition). Plant Protection Society of Western Australia, Perth, Western Australia. P148. Photo.

Paczkowska, G. and Chapman, A. (2000). The Western Australia flora: a descriptive catalogue. (Wildflower Society of Western Australia (Inc), the Western Australian Herbarium, CALM and the Botanic Gardens & Parks Authority). P247.

Randall, J.M. and Marinelli, J. (1996) Invasive Plants. (Brooklyn Botanic Gardens Inc. Brooklyn). P. Photo.

Links:

http://www.nationaalherbarium.nl/euphorbs/spech/homalanthus.htm#Homalanthus arfakiensis

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.