WEED ALERTBushland Weeds

of the UpperOnkaparingaCatchment

A native to the Mediterranean,Montpellier Broom was introduced toAustralia as a garden plant. It grows to3 m and has foliage which is soft totouch with fine hairs on both sides.Leaves are divided into three leaflets.Yellow pea-shaped flowers appear inspring.

Montpellier Broom is highly invasiveand is often found along the marginsof bushland, before expanding intoless disturbed areas. It exploits asimilar niche to many indigenousunderstorey plants and thereforedirectly competes with them forresources and space.

Broom spreads from seed which isable to lay dormant in the soil for manyyears and germinate in response todisturbance. Seed can also be spreadby birds, ants, livestock, machineryand water.

As the common name suggests,English Broom was introducedfrom the UK as a garden plant. It isstill commonly found in localcommercial plant nurseries.English Broom grows to 4 m andhas erect or arching brancheswith ribbing pattern along them.Leaves are divided into threeleaflets, smaller and darker greenthan Montpellier Broom. Pureyellow or yellow and red pea-shaped flowers occur in springand summer.

Like Montpellier Broom, EnglishBroom spreads from seed whichis able to lay dormant in the soil formany years which germinates inresponse to disturbance. Seedscan be spread by birds, ants,livestock, machinery and water.

Montpellier BroomGenista monspessulana

English BroomCytisus scoparius

African Weed-orchidMonadenia bracteata

Sweet Pittosporum

Pittosporum undulatum

African Weed-orchid was firstrecorded in SA in the late 1980sand has now spread to woodlands,roadsides and grazing country.This plant has single, paired orclustered leaves emerging in earlyspring, which are green on theupper side and purplish redbeneath. Leaves are followed by astem to 40 cm high which is upright,green and fleshy with 20-60 smallflowers along it.African Weed-orchid excludessmaller indigenous flora such asOrchids, Lilies and grasses.Flowering and seeding occur overlate spring to early summer witheach flower potentially producing1000 tiny seeds. Seeds aredispersed by animals, clothing orearth moving activities and canremain viable for up to 7 years.

An north-eastern Australiannative Sweet Pittosporum is notindigenous to SA. It is a denselyfoliaged evergreen tree or shrub4-14 m high. Leaves are a shinydark green on top and lighterunderneath with a prominent mid-vein. Creamy white, fragrantflowers appear from mid-winter toearly spring, followed by orange-coloured fruit.

Sweet Pittosporum providesdense shade and conditionsbeneath the tree which naturallyexclude indigenous plants andfavour weeds.

This tree has been introduced tothe hills by gardeners where birds(mostly European Blackbirds)consume the fruits and spread theseed into bushland areas.

Erica is a shrub to 3 m whichoriginates from south-west Europeand is often mistaken as anindigenous plant. It is dense andmulti-stemmed with small leavesoccurring in crowded whorls alongthe branches. Pink flowering budsemerge in winter and open intodense clusters of mostly white, bellshaped, flowers approximately 5mm long.

Erica is commonly found along theroadsides and other disturbed areasbut can also expand into bushland.It exploits a similar niche to manyindigenous understorey plants andtherefore directly competes withthem for resources and space. Ericaspreads via fine seed which istransported by animals, vehiclesand machinery.

As the name suggests African Daisy

originates from Africa. It is an erect,

hard, sometimes woody stemmed

shrub to 3 m high. Leaves are dark

green above and white and woolly

below with toothed edges. Dense

yellow flowers are produced in

summer and autumn.

During the 1960s, the Adelaide Hills

were heavily infested with African

Daisy which flourishes in the

moderate to high rainfall areas.

African Daisy seeds are adapted for

dispersal by wind and water but most

seeds fall close to parent plants.

Spread is mainly through surface

water movement and within mud

stuck to animals, clothes and

machinery.

African DaisySenecio pterophorus

Tree Heath, SpanishHeathErica spp.

A native to South Africa, Bulbil

Watsonia was introduced as an

ornamental garden plant.

Leaves are flat and sword-like to 80

cm emerging from bulb-l ike

structures called bulbils, in winter.

The flowering stem develops in

spring with tubular, mostly orange

flowers.

Watsonia dies back over summer,

forming dense mulch which stops

regeneration of other species. It is

widespread but forms the most

dense infestations in moist areas.

It spreads mostly from new bulbils

which appear on the flowering stem

post-flowering which germinate the

following winter.

Bulbil WatsoniaWatsonia meriana var.bulbilifera

Sydney Golden WattleAcacia longifolia var.longifolia

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AnAustralian native, not indigenous

to the area, Sydney Golden Wattle

has found its way here from Eastern

States as a garden plant.

Sydney Golden Wattle has long

flower spikelets.

It is now appearing in many hills

locations including roadsides,

bushland and watercourses. This

means it is competing for space with

local Wattle species and growing

‘unchecked’ from insects and other

predators and parasites which

would otherwise help in its control

within its normal distribution area.

Seeds are dispersed by birds such

as Lorikeets and Rosellas and in

surface water flow.

Photo: K Blood 2001CRC Weed Management Systems

Environmental weeds: a fieldguide for SE Australia