Description
Garden Geranium (Pelargonium alchemilloides) is a very widespread species in South Africa and is quite variable from location to location (CRC 2003b). It is a straggling perennial herb, usually about 200 mm high, with spreading stems arising from a woody tuberous or stoloniferous rootstock.
The stems are covered with long, coarse hairs and are produced from a central rosette of leaves.
The flowering branches produce flowers in clusters of three to six, sometimes up to 15, from the tip of the branch (Van der Walt 1977). Leaves are two to seven cm in diameter, five to seven lobed to at least half way to the base and the lobes are irregularly toothed.
The leaves have a silky appearance due to a dense covering of hairs and some have a purple, brown or dark red horseshoe-shaped zone.
Flower colour is usually white, cream or pink. White or cream flowers occasionally have pink or red markings. Pale yellow flowers have also been reported. Flower size is quite variable. The petals range from 10 - 20 mm long and 2 - 10 mm wide. The showiest forms have quite large white or deep pink flowers and often have silvery leaves.
For further information and assistance with identification of Garden Geranium contact the herbarium in your state or territory.
Distribution:
At present, Garden Geranium is very localised in south-western Western Australia. It is known from one site along a roadside two km east of Hamelin Bay where it has invaded adjacent vegetation. It is currently distributed patchily across an area of approximately 10 hectares.
Climate and soils suitable for Garden Geranium are found in much of southern and central Australia including parts of all southern states, from semi-arid to temperate pastoral country on sandy coast soils.
Habit:
Herb
Key points:
- Garden geranium (Perlargonium alchemilloides) is a garden plant from Africa that is now invading indigenous bushland and has the potential to threaten agriculture.
- It is currently known to be naturalised in only one small area in south-western Western Australia but is considered to have the potential to invade much of southern Australia.
- It is a prolific seeder and can also spread vegetatively from tubers and stem pieces.
- It is able to invade disturbed areas and survive hot dry conditions.
- Any new naturalised occurrences should be reported to the relevant weed management agencies.
How it spreads:
Garden Geranium is a prolific seed producer and can also be propagated by stem and tuber cuttings. The tuberous rootstock enables it to survive harsh dry periods and times when seed production is not successful.
The seeds can remain viable in the soil-stored seedbank for a long period of time due to the presence of chemical inhibitors that prevent all seeds germinating at the same time. Soil disturbance is thought to have been the major cause of the recent population increase in Garden Geranium at the Hamelin Bay site, as the rate of spread was slow until roadwork’s using graders and trucks occurred. Seeds germinate and pieces of underground stem grow into new plants when soil is disturbed.
Where it grows:
In South Africa, Garden Geranium occurs in grassland and disturbed areas across a wide area with a climate ranging from Mediterranean in the southwest to temperate in the interior plateau and subtropical in the northeast (Victorian Department of Primary Industries).
It is believed that the southwest form is present in Australia and is highly adaptable to the climate of southern Australia.
At the Hamelin Bay site it has invaded low Agonis flexuosa (peppermint) woodland on sandy coastal soil. The first collection was made from low dunes in grey sand over sand.
The average annual rainfall for Hamelin Bay is 1000mm.
Flower colour:
White, Pink, Yellow
Distribution map:
Impacts:
Garden Geranium is on the Alert List for Environmental Weeds, a list of 28 non-native plants that threaten biodiversity and cause other environmental damage. Although only in the early stages of establishment, these weeds have the potential to seriously degrade Australia’s ecosystems.
The current impacts of Garden Geranium in Australia are on environmental and biodiversity values. It has invaded intact indigenous vegetation and threatens to outcompete understorey plant species and associated fauna at the Hamelin Bay site. It is considered to have the potential to have these kinds of impacts over a considerable area of southern Australia. It is also assessed as having the potential to impact negatively on agricultural production because it can colonise disturbed sites, seed prolifically and survive harsh conditions.
Origin:
Garden Geranium occurs in grassland throughout southern Africa, extending northwards through tropical Africa into Ethiopia and Somalia.
History:
Garden Geranium was originally introduced to south-western Western Australia when planted in gardens. It has been estimated that initial introduction to the Hamelin Bay area took place in the early 20th century when a timber settlement occurred there. This plant is often found growing in disturbed areas.
The first naturalised collection of Garden Geranium from the Hamelin Bay site was made in January 1988, at which time it was described as abundant.
