Asparagus spp.
There are many Asparagus
spp. that have become environmental weeds in Australia. Details of the two that
are impacting on Helensburgh and surrounding areas are below.
Asparagus fern (Asparagus aethiopicus)
Bridal creeper (Asparagus asparagoides) (Weeds of
National Significance*)
Origin: Africa.
How it spreads: Dumping of garden waste. Seeds are dispersed by birds and small animals. Asparagus species are highly invasive
environmental weeds.
Effects on the
Environment
The ability to abundantly produce seeds and flowers enables
asparagus fern and bridal creeper to quickly invade and suppress other plants.
Asparagus fern
Asparagus fern swiftly attacks any disturbed, cleared sites
of vegetation. The plant has become a dominant ground cover, displacing native
plants. With its mat of fibrous roots and tubers, the plant has the ability to
take over the soil, trapping water and nutrients and so reducing their
availability to native plants.
Bridal creeper
Bridal creeper forms large underground rhizomes. It twines
up into surrounding vegetation, eventually covering the ground and any plants.
Asparagus fern is a multi-branched prostrate herb forming a
dense mat of roots. The fern-like branches grow to 60cm with a covering of
small sharp spines. The plant has small white-pink clusters of flowers in late
summer which ripen to bright red berries. These 'ferns' will overtake natural
species by developing dense thickets that deprive other plants of light and
nutrient as well as destroying habitat.
Removal: The
central rhizome must be removed. For small plants lever the plant up with a
hand tool. For larger plants, cut off the stems, then clear around the rhizome
cutting the roots and levering out the rhizome. Dispose of rhizome and any
fruit in the red bin. Water tubers
and roots can be left as they will not reproduce.
Bridal creeper stems are long and wind around
vegetation or
scramble along the ground. They range
from 1-3 m in length and can be slightly
woody at
the base. Leaves grow alternately along the stem, are bright green,
thin and glossy, are 1-7 cm long and have around seven parallel veins. Flowers
are white and bell-shaped and grow singularly or in pairs along the stem. Fruit
is bright orange to red berries. Roots are dark, cylindrical branching rhizomes
bearing pale, fleshy tubers which become entwined together forming a dense mass
about 5-10 cm deep in the soil. The stems arise from the rhizomes.
Removal: Hand pull and dig out the rhizomes. All
underground material should be removed and follow up will be required. Dispose
of rhizomes and any fruit in the red bin.
For more information on control and removal of Asparagus species, see here
Grow Me Instead
Prostrate
Grevillea
species
As
groundcovers there are several prostrate or low mound-forming Grevilleas, some
of which even have similar foliage to the asparagus ‘ferns’, though they will
not tolerate such shady conditions Grevillea obtusifolia and Grevillea juniperina ‘Molonglo’
with yellow to apricot flowers are just two of many available.
This
evergreen vine from China has dark, glossy foliage and small, starry, white,
spicy, nutmeg-scented flowers in summer. It is slow growing initially but later
becomes vigorous. Variegated leaf forms are also available.
* Thirty two Weeds of National Significance (WoNS) have been agreed on by the Australian governments based on an assessment process that prioritised these weeds based on their invasiveness, potential for spread and environmental, social and economic impacts. Landowners and land managers at all levels are responsible for managing WoNS. State and territory governments are responsible for legislation, regulation and administration of weeds.
