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Conserving native cress

The tiny native cress, Ballantinia antipoda (F.Muell.) E.A.Shaw is currently known from just a few mossy mats on a single granite mountain, Mt Alexander, in central Victoria. A large plant is 5 cm high and, in nature, typically lasts just a month or so.

The type collection was from Tasmania, but the species in now extinct in that state.  It was previously known from a few other sites – all granite outcrops of the Victorian midlands.

Some seed of this was held at the Victorian Conservation Seedbank (VCS), from wild collections and subsequent seed-orcharding. Recently, the species was prioritised by Department of Environment and Primary Industries (DEPI) for ‘translocation’ via direct seeding, into new, secure site near Mt Alexander.

The seed is minute, so a thousand or two doesn’t go very far. We really needed to know how to optimise germination conditions to make the most of DEPI’s translocation effort. Meg Hirst, seed technician at VCS, contacted colleagues at the Botanic Gardens of South Australian to see if it were possible to beg, steal or borrow some time and space on their thermogradient plate. Folk there were welcoming, so Meg, armed with her precious cargo, set off for Adelaide to set up the experiment with Dr Jenny Guerin of the SA Seed Conservation Centre. A few weeks later the seedlings were telling their story, “Give us some GA [gibberellic acid] and 3 weeks at 14°C please”.

The attempt to create a ‘new’ population has commenced and fingers are crossed. In the meantime, plants produced from the germination test are being orcharded in nursery at the Royal Botanic Gardens Melbourne (a Lilliputian orchard indeed) to replenish the VCS stocks of this extraordinary little plant.

(Prepared by Neville Walsh, Royal Botanic Gardens Melbourne)