Wednesday, July 21, 2010

TUGGERANONG LIGNUM

A nearly extinct plant clings desperately for survival at 550 meters above sea level on the eastern banks of the Murrumbidgee River at Canberra. Originally discovered in Tuggeranong in 1997 "Muehlenbeckia Tuggeranong" was first described (info) from a single female plant and six male plants that were found in the Murrumbidgee River Corridor at Pine Island (post here) in the Australian Capital Territory. In May 1999 one more male plant was discovered a short distance from the other seven plants. This brought the total to 7 male and one female plant known to exist.


Tuggeranong Lignum is a sprawling woody shrub that grows to 1 meter high in a loose tangled mound of wiry stems extending between 1-2 meters across. The plant has singular green ovoid leaves that grow at intervals along the length of the stem. The flowers are cream-green on a lax spike. Flowering occurs from December and late March annually. It grows in medium to course textured alluvium, mainly quartzitic sand and gravel, with local richer pockets of silty sand soil.


The plant grows in pockets in rocky outcrops on the edge of the river. These river bank terraces are prone to seasonal flooding events with some plants being only 1.5 meters above the flow line of the river. Other plants grow not far up a gentle slope. Although extensive searches have been carried out this population appears to be the only one in existence.



The river at the location is typified by rapids, boulders and sand beaches with uneven rocky flood terraces.


Attempts are being made to establish a second population at Pine Island of plants propagated for the purpose. It remains to be seen if the new population will have the genetic diversity required to re-establish.
  • A new species R.O Makinson and D.J Mallinson (here)
  • National recovery plan for Tuggeranong Lignum (here)
PINE ISLAND TUGGERANONG

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