Trailing Snapdragon (Asarina procumbens), a perennial snapdragon originating in the south of France where it grows in rock crevices. Broadly adopted as an ornamental selection, the species has been recorded as a garden escape in northern Europe.
We should be clear here that Trailing Snapdragon has not naturalised in Australia. Yet it can be found growing in weedy contexts in Melbourne’s inner suburbs: on or under structures, fences, kerbs and pavements; places where it wasn’t meant to be growing.
These ‘weed’ instances of the plant are short-lived and unlikely to spawn further generations of the plants. This is because Snapdragon flowers are generally adapted for buzz pollination by bumble bees, and resist smaller pollinators such as honeybees and native Australian bees. Most occurrences of the plants are perhaps more likely to represent wind-blown drift of packaged seed than they are a very rare seed-setting event among cultivated plants. This doesn’t make them any less fascinating as weeds when they do appear.
However, it is also notable that the presence of bumblebees in Tasmania (they will presumably cross the Bass Strait eventually) means that quite a number of buzz-pollinated species which have been ‘safe’ horticultural selections in Victoria may become future problems. In Tassie, the bumblers are now being blamed for a Rhodo explosion, with further sticky problems presumably only a matter of time.