Family: various

Status:

Description:
Several succulent plants commonly cultivated in gardens are capable of becoming naturalised in nearby bush, particularly if they are dumped there. Century plant (Agave americana) is a large plant consisting of a rosette of erect broad, sword-like grey leaves with toothed margins. It flowers in a tall branched head very infrequently (but probably more often than the 100 year intervals suggested by its name) and then dies, to be replaced by numerous seedlings. A similar but smaller plant is soap aloe (Aloe maculata). Probably the most commonly naturalised succulent is the aptly named mother-of-millions (Bryophyllum delagoense) which spreads by producing thousands of small plantlets at the tip of each leaf. Stonecrop (Crassula multicava and other species) also spreads from gardens into nearby native vegetation, as occasionally will Sedum species.

Preferred habitat and impacts:
Succulents are highly tolerant of dry conditions and shallow or infertile soils. They may invade areas of rocky outcrop, displacing native plants which are confined to such sites. They may also spread into open forest and grassy remnant vegetation but are unlikely to invade very shady or wet sites.

Dispersal:
Mostly spread vegetatively by dumping of garden waste, but century plant occasionally spreads by seed, and mother-of-millions spreads prolifically by small plantlets produced vegetatively at the leaf tips.

Look-alikes:
There are a few native succulents which grow around rock outcrops but they are generally very much smaller than the garden escapees. All the exotic succulents have much larger flowers. Australian stonecrop (Crassula sieberiana) is an erect or sprawling plant to about 15cm long, with tiny greyish leaves and very inconspicuous flowers. Another rock plant is Calandrinia pickeringii which has small sausage-shaped leaves 1.5-7cm long and small pink flowers.

Control:
Do not dump succulents, or grow them in gardens adjacent to native vegetation.

Infestations can be dug out, but will need to be burnt or deeply buried to prevent the plants from taking root again. Succulents will remain capable of re-sprouting for long periods after digging up. Some herbicides may be effective, but high concentrations are likely to be needed because of the waxy coating on the leaves.