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20 Mar 2018

Scientists gone wild in the Watchimbark Nature Reserve

In January, five botanists from the National Herbarium at the Royal Botanic Garden Sydney visited Watchimbark Nature Reserve in Curricabark to undertake fieldwork. Watchimbark Nature Reserve covers a highly unusual geological unit that contains a small area of exposed serpentine bedrock.

The aims of the two day field trip were to collect additional specimens of recognized putative new taxa, in order to resolve their status and formally describe them; to collect generally within the reserve to better document the flora; and to photograph species for online identification resources such as PlantNet

Cryptandra sp. image taken by Dr Russell Barrett

Serpentine Rocks & Vegetation

Serpentine rocks are the result of an unusual geological process, obduction, by which heavy rocks of seafloor crust (ophiolites such as serpentine) get placed on top of lighter rocks of continental crust. The high heavy metal content of serpentine rocks means that plants growing in serpentine areas are often restricted to them, and serpentine areas the world over have narrow range edaphic endemic plants.  Serpentine is an uncommon rock type in Australia, making Watchimbark highly unusual within a national context. 

Witchimbark Reserve
Watchimbark National Reserve image taken by Dr Russell Barrett

The reserve has its own mallee eucalypt, and several other species of restricted distribution occur in the reserve, including Grevillea granulifera (Proteaceae).  Previous botanical surveys have identified several putative new species, including Astrotricha sp. ‘Watchimbark’ (Araliaceae) and Plectranthus sp. aff. argentea (Lamiaceae), for the latter no herbarium specimens exist.  Furthermore, within the reserve, most collections have been made in the western part of the serpentine vegetation only, and no bryophytes have been collected from within the serpentine area. 


A number of interesting collections were made in the reserve, including a specimen of Hibbertia belonging to the H. riparia complex (Dilleniaceae) that may be a new species; two Lepidosperma species that could both be new serpentine endemic species (Cyperaceae); an unusual Arthropodium (Asparagaceae) that does not match any of the concepts in the Flora of New South Wales.

Hibbertia riparia
Hibbertia riparia image taken by Russell Barrett

We also obtained good collections of other known serpentine endemics, and for one of our target species, we resolved that Astrotricha sp. ‘Watchimbark’ comprises not one, but two unusual forms.  One of these belongs to the A. longifolia complex, and we located and collected good material of this.  The other, which we did not see, belongs to the A. latifolia group.  Neither did we relocate the Plectranthus aff. argentatus, so both will have to be the focus of another trip.
Bryophytes were collected for the first time in the reserve, all will therefore be new records.  They should be interesting given the unusual substrate, and general paucity of bryophytes within the serpentine vegetation.

Unfortunately, the field trip was cut short by an urgent but orderly discretionary evacuation ahead of a fire that kicked off in the eastern part of the reserve, in tall forest beyond the serpentine vegetation.
Support from Sean Thompson, Ranger for Watchimbark Nature Reserve is gratefully acknowledged. 

Arthropodium images by Dr Russell Barrett


Dianella image taken by Dr Russell Barrett

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Category: Field Trips
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