Status:

Preferred habitat and impacts:
Beaches and dunes, and adjacent sandy areas, including off-shore islands. Most of these plants tolerate burial, and will continue to grow until they reach the surface again, as they need to do to survive in the very changeable beach environment.

These plants compete with native beach and dune vegetation, such as spinifex grass (Spinifex sericeus). Some are more strongly sand-binding than the natives, resulting in dunes becoming steeper. The photograph shows beach daisy trapping sand at the mouth of Wallagoot Lake on the far south coast. Such infestations could ultimately affect the opening behaviour of coastal lakes, if allowed to spread unchecked.

Dispersal:
Seed of many beach species remains buoyant and viable in the sea, and can be spread along the coast in currents. Sea spurge seed is released explosively to 2m from the parent plant. Some species can attach to clothing or be spread in sand removed from beaches, or on vehicles which are driven on beaches. Hare’s tail grass is often collected for dried flower arrangements or by children and later discarded.

Look-alikes:
No closely similar plants to any of these species are likely to be found on beaches, except for marram grass, which has several native look-alikes. These are the robust tussock grasses beach fescue (Austrofestuca littoralis), beach poa (Poa poiformis) and beach speargrass (Austrostipa stipoides). All are about 1m high, with in-rolled, bristle-like leaves to reduce water loss from the leaf surface in this drying environment. Marram grass can be distinguished from the natives by checking the ligule, a flap of white or translucent tissue which is found on the inner surface of the leaf sheath, at the point where the leaf joins the stem. In marram grass the ligule is very long, 20-30mm, compared with only 1-2mm in beach fescue and beach poa, and 4-9mm in beach speargrass. Its leaves are not tightly rolled, are blue-green and have a glossy plastic-like upper surface.
There are many native species of pennywort (Hydrocotyle species) but they are less likely to occur on beaches. Few have the leaf stalk inserted in the back of the leaf as beach pennywort does. A small native plant in the convolvulus family, Calystegia soldanella grows on beaches. It has kidney to heart-shaped fleshy leaves and pink morning glory-like flowers. It spreads by underground runners like beach pennywort.
A mat-forming, fleshy-leaved native which could perhaps be confused with beach daisy is Scaevola calendulacea. It is similar in habit, but not really in appearance, having green leaves, purple flowers and large succulent purple fruits.

Control:
Hare's tail grass is only a minor weed, and pennywort and sea rocket are too well established on south coast beaches to be controllable. However, beach daisy and sea spurge may still be eradicable from some of the beaches in the region on which they have recently become established.
Hand-pull or dig plants and remove for safe disposal. Plants left lying on the surface may take root again, or drop seed.
Marram grass has been planted for dune stabilisation in the past. Dunecare groups should avoid planting species on beaches which are not local natives. It is always preferable to plant only locally native species from locally collected seed. Some Australian native plants have had their range extended by being planted for dune stabilisation outside their natural distribution. An example on the south coast is coastal tea-tree (Leptospermum laevigatum ), which grows north from Jervis Bay and south of Eden, but does not appear to occur naturally on the stretch of coastline between those places. However, it has now been widely planted and is naturalising within that area, obscuring information about its natural distribution, and potentially displacing locally native species (see section on natives as weeds).