Purple pea back from the brink
Five years ago, the Melbourne Gardens Nursery team at Royal Botanic Gardens Victoria was approached by the Department of Environment, Land, Water and Planning (DELWP) to save the Mountain Swainson-pea (Swainsona recta), as part of Victoria’s major preservation plan, Biodiversity 2037.
Declared extinct in Victoria, the last known Victorian population of the Mountain Swainson-pea was found in the state’s north east, in Chiltern-Mt Pilot National Park. The group consisted of just four individuals, all descendants from the one plant, which eventually died in 2012.
The drastic decline in the numbers of this native legume has mainly occurred since European settlement, facing challenges such as urban and agricultural development, domestic stock grazing and competition from introduced plant species, amongst others.
With only 340 Mountain Swainson-pea seeds available, the effort to turn them into seedlings in the Nursery was challenging. The seeds remain dormant until they are triggered to germinate, and for this project, the seedlings needed to grow simultaneously for planting.
Due to the rarity of this plant, the Nursery team decided that the seeds would need to be triggered individually. This was done by hand, using a microscope and scalpel.
“The seeds are very small in size – about a quarter of a match head – and have a hard coating that needs to be scarred in order for them to absorb water, germinate and eventually grow. In the wild this is done by fire or the passage of time abrading the hard seed coat. In the Nursery, it is done by hand” said David Robbins, Team Leader Nursery at Melbourne Gardens.
Since then, DELWP has supplied Melbourne Gardens with more Mountain Swainson-pea seeds. Last year alone, 1,181 seeds were supplied; all were then scarified, resulting in 784 young plants. From this stage, they were closely nurtured and monitored for pests and infection. These were planted in Chiltern-Mt Pilot National Park and throughout the state’s north east, with the final planting completed in July.
By the end of this project, the Melbourne Gardens Nursery team managed to successfully propagate and supply over 1,500 Mountain Swainson-pea seedlings for reintroduction into the wild – bringing this purple pea back from the brink.
This project was made possible with thanks to DELWP Hume Region in partnership with agencies, community groups and private landholders.
Partners in the collaborative project include North East Catchment Management Authority, Royal Botanic Gardens Victoria, Trust for Nature, Parks Victoria, Friends of Chiltern-Mt Pilot National Park and Landcare groups and networks across the north east.