Australian Native Ground Covers with a Weedy Nature

Author & Photos: Lawrie Smith AM, landscape architect

Published: Journal December 2022 

Since moving from acreage to a small residential garden five years ago, I have been researching and trialling a range of low growing plants and ground covers suitable for small gardens. Plants like this are invaluable as an effective living mulch to reduce transpiration, a weed suppressant and also to be generally aesthetically pleasing. A reasonable selection of such plants are available commercially, but in this story, I have concentrated on four I have found to be hardy and even rampant, with a tendency to become weeds.

Youngia japonica

If you have this plant in your garden it is easy to identify, in fact there will probably be thousands in all stages of development! This ‘native?’ annual pest produces small yellow daisy flowers in loose panicles for most of the year, held on solitary and erect stems, ranging from 100mm to 500mm, depending on growing conditions. Being Asteraceae family, its seeds are regularly and widely dispersed floating on every breeze and wind. They germinate anywhere, disturbed areas, cracks in paving, dry or moist gardens, sun or shade, does not matter! Leaves are lobed with toothed margins and clustered in a rosette at ground level emerging around the root system. This pesky plant is most easily removed from moist soil by gently pulling low down on an unopened flower spike, when most likely it will release its root grip on the soil.

Mazus pumilio

Swamp Mazus

Almost as bad as Youngia, this decorative prostrate herbaceous perennial, has rosettes of leaves emerging from underground rhizomes and naturally forms wide, spreading, and dense carpets. In spring and summer attractive small purple and white flowers are produced, supported on slender stems just above the apple green foliage. Native to eastern Australia, Tasmania and New Zealand, it is frost and drought tender, but excellent for moist spots in the garden or around pond edges in full or part shade.

Mazus pumilio dominated the Chrysocephalum apiculatum 

During the warmer months it will spread rapidly with the adventitious rhizomes travelling unobserved under grass or mulch, then bursting forth with the attractive fluted edge foliage. Removal is difficult unless every last piece of the rhizome is removed. Nevertheless, it makes a very attractive ground cover requiring minimum maintenance, but be very careful where you plant it as it will swiftly smother any other low growing cover.

Cyperus gracilis

Slender Flat Sedge

This common densely tufted grasslike plant with slender apple green foliage, is one of many sedges native to Australia. The species name ‘gracilis’ refers to the graceful form of the arching leaves. It grows from 100mm to 300mm in height and is quite adaptable and hardy once established, often self-sowing around the parent plants to form a groundcover. Small yellow-green inflorescences are held on stalks above the foliage in spring and summer. Cyperus gracilis is found from Victoria, north to New South Wales and Queensland, in habitats ranging from high rainfall areas near the coast, to drier areas in woodlands. It is also naturalised in Norfolk Island, New Caledonia, the Canary Islands, Hawaii, and California. While not as much of a nuisance as others on this list it never the less establishes readily in seed trays, potted plants, in paving cracks, mulches and garden edges, and fortunately it is easy to manually remove.

Cyperus gracilis

Apowollastonia spilanthoides

Beach Sunflower or Rough Wedelia

Apowollastonia spilanthoides was originally known as Wedelia spilanthoides (a much easier name to pronounce!) Variously known as Beach Sunflower or Rough Wedelia, it is found in the drier woodlands, sand dunes and rockfaces along coastal and inland Queensland from Cape York to the border. It has differing visual attributes in the various regions – some lush and green, others open and spindly. This herbaceous cover is generally prostrate, but may layer up to 500mm, often rooting at the nodes to make an excellent soil binder. The intertwining thin rough dark stems, support linear-lanceolate, toothed leaves, 25mm to 10 mm long, 7mm to 15mm wide, sometimes lobed at the base. These form a dense dark green cover shading out any weeds below. Decorative bright yellow daisy flowers 15mm to 20mm diameter scattered over the foliage for the warmer months of the year, provide a vivid focal point for the garden.

This hardy, prostrate groundcover can tolerate salty winds and minimal water to bring colour to even the harshest of localities. Regular tip pruning produces a dense leaf canopy and reinforces the prostrate nature. Once established, it will spread and root rapidly so regular pruning of adventitious branching will be necessary to maintain it within the desired garden location. All things considered it is a very useful ground cover particularly for the more difficult drier, sunny garden if managed appropriately.

Apowollastonia spilanthoides close up of flowers

What other species have you found troublesome?

These four species add significant extra maintenance time to my gardening activity and it would be very interesting to know from our members, which other native species have created similar problems for them due to their weedy nature. Share your experience in the next Journal so that we can all be forewarned of problems to expect and perhaps what not to plant.