Squirting Cucumber (Ecballium elaterium), a Spanish-origin, pan-Mediterranean poisonous weed likely distributed to Australia with imports of Merino sheep.
The plant is appropriately named—as a relative of edible cucumbers, melons and squashes in Cucurbitaceae, and as a plant with the unusual adaptation of fruit structured to squirt seeds long distances when stepped on by hooved or booted mammals.
Squirting Cucumber was found naturalised in waste land around Geelong in 1907, and by 1917 it was found to be established within the metropolitan along the Werribee River. Its concentration (then and now) in the pastoral desert of the Western District is suggestive that the first weedy plants arrived with sheep (and accompanying hay) imports, rather than escaping from medicinal plantations. Official botanical records follow the highways, but the species is likely established on a variety of private land that is simply not subject to regular botanical inventory. In Melbourne, the species has only been recorded west of the Maribyrnong, on an arc north-west through south-west from Yarraville and centred on transport and refinery infrastructure.
The photographed plants were found extensively distributed along the Kororoit Creek Trail in Altona North, on high, dry ground and in a mix of settings ranging from low-management grassland to prepared native revegetation beds.