Buckthorn

Rhamnus alaternus L.

Synonyms -

Family: Rhamnaceae

Names:

Rhamnus is the Greek name for a shrub.

Other Names:

Alaternus after its species name.
Blowfly Bush
Evergreen Buckthorn (NZ)
Italian Buckthorn
Mediterranean Buckthorn

Summary:

Buckthorn is a dense, hairless, evergreen shrub or small tree to 6 m high with shiny dark green leaves. The leaves are elliptic, 20-40 mm long with the margins thickened and minutely toothed. The clustered pale green flowers are small, unisexual with the male and female flowers on separate plants. The petals are either absent or shed early. The fruits are fleshy, red to black at maturity, egg shaped and 5-6 mm long.
Native to the Mediterranean region, spread by birds and now naturalised in disturbed bushland and in coastal scrub and dunes. It flowers in winter.

Description:

Cotyledons:

Two.

First leaves:

Leaves:

Alternate sometimes somewhat paired. Dark green, shiny. There is a variegated leaf form with creamy white edges.
Stipules - Often present, paired, to 1.5 mm long.
Petiole - Yes.
Blade - Leathery, elliptic, 20-80 mm long x 10-40 mm wide with the margins thickened and entire or minutely toothed with sharp or blunt teeth. The upper surface is dark green and shiny and the lower surface somewhat paler. Hairless. Prominent veins.

Stems:

Up to 6 m but more commonly 2-4 m or stunted in harsh environments. Densely branched from ground level. Smooth, purplish, angled and with very short hairs when young, hairless later.
Becomes grey brown with age. Remnants of stipules and petioles persist on older stems for some time.

Flower head:

Clusters of small pale green flowers arise from the leaf axils. Usually a hairy, scale leaved raceme or panicle. Flowers on 1-3 mm long stalks (pedicels).

Flowers:

Small, greenish, 3-4 mm diameter, hairless, star shaped, fragrant, unisexual with the male and female flowers on separate plants.
Ovary - Superior. Long deeply 3-branched style.
Sepals - 5 pointed lobes, 1-2 mm long. Turned back with red edges in female flowers or erect in male flowers.
Petals - 5 or absent or shed early.
Stamens - 5. Inserted at the base of the sepal lodes.
Anthers - Elliptic obtuse.

Fruit:

Fleshy, glossy, initially green turning red then black at maturity, egg shaped and 5-7 mm long x 4-5 mm wide. 2 or 3 celled. Usually with 3 bony, 1 seeded nutlets.
Drupe. Large amounts are produced over summer.

Seeds:

Long lived.

Roots:

Woody branching taproot that is thickened at the crown which vigorously sprouts if damaged. Woody lignotuber often positioned at an angel to the main trunk and at least the same diameter as the trunk. Suckers readily from the lignotuber and thick lateral roots.

Key Characters:

Glabrous, evergreen, dioecious shrubs.
Ovary superior and free from the floral tube
5 stamens.

Biology:

Life cycle:

Evergreen perennial shrub with a fast growth rate.
Germination occurs mainly in autumn and spring if moisture is available. Initial growth is slow while the root system establishes. Prefers disturbed habitats but can germinate and grow in shaded situations in established vegetation. It suckers freely from the roots and base and usually survives fire and cutting. It lives for many years. It can set seed at two years old.

Physiology:

Cold tolerant.
Drought tolerant.
Tolerates frost to -150C
Tolerates salt spray.

Reproduction:

Seeds and suckers and coppices freely.

Flowering times:

Late winter to early spring in Victoria.
August to September in SA.
May to October in Victoria.
June to November in WA.
May to November in NZ.

Seed Biology and Germination:

Germinates best in the dark. The seed longevity in the soil is long.

Vegetative Propagules:

Resprouts from crown when the top growth is damaged or removed.

Hybrids:

There is a variegated leaf form with creamy white edged leaves.

Allelopathy:

Population Dynamics and Dispersal:

Spread by birds and possibly foxes and possums, dumping of garden refuse and intentional planting.

Origin and History:

Native to the Mediterranean region.

Distribution:

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

Courtesy Australia's Virtual Herbarium.

Habitats:

Naturalised in dry sclerophyll forest, disturbed bushland, coastal scrub and dunes, heathlands, escarpments and riparian areas.
Full sun to partial shade.

Climate:

Mainly in areas with more than 500 mm annual rainfall.

Soil:

Grows on a range of soil types. More common on sandy and loamy soils along waterways. Tolerates limestone soils.

Plant Associations:

Often associated with trees or structures where birds perch.

Significance:

Beneficial:

Ornamental and hedges.

Detrimental:

Weed of bushland, heathlands, riparian areas and plantations.
Forms dense thickets where little else grows.

Toxicity:

Symptoms:

Treatment:

Legislation:

Declared in all states. Weed of National Significance.

Management and Control:

Hand pull or dig small plants less than 500 mm tall. Roots will resprout if left in the ground. Manual removal is usually difficult for large plants because of the strong root system.
Cut and paint, drill and fill or basal bark treatments work best in spring but some follow up applications are required for high levels of control.
Overall sprays are most effective on seedlings and plants up to 2 m tall.
It is relatively tolerant to glyphosate.

Thresholds:

Eradication strategies:

Use a basal bark spray. Burn if possible. Spray with Grazon.

Herbicide resistance:

None reported.

Biological Control:

Related plants:

Chinee Apple or Indian Jujube (Ziziphus mauritiana) a declared weed is in the same family.
Native Cryptandra, Pomaderris and Spyridium are in the same family

Plants of similar appearance:

Sea Box (Alyxia buxifolia) has opposite or whorled leaves.
Cotoneaster (Cotoneaster glaucophyllus, Cotoneaster pannosus) has red berries when ripe.
Bitterbush (Adriana quadripartia) usually has opposite leaves and they are broadly serrated.
Mirror Plant (Coprosma repens) has pits (domatia) where the leaf veins join the midrib.

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P545. Diagram.

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

Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P76-77. Photos.

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).

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

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. P224. Photo.

Lazarides, M. and Cowley, K. and Hohnen, P. (1997). CSIRO handbook of Australian Weeds. (CSIRO, Melbourne). #850.1

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P459-460.

Moore, J.H. and Wheeler, J.R. (2013). Southern Weeds and their Control. (Second Edition). South Coast NRM and Department of Agriculture and Food Western Australia. P. Photos.

Muyt, A. (2001). Bush Invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South East Australia. (R.G and F.J. Richardson, Australia). P213-214. Photos.

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). P509.

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

Roy, B., Popay, I., Champion, P., James, T. and Rahman, A. (1998). An Illustrated Guide to Common Weeds of New Zealand. (New Zealand Plant Protection Society). P259. Photo

Acknowledgments:

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