July 15, 2023

Horny and dying

Isopogon ceratophyllus (Horny Cone Bush) is a small, densely spiky shrub in the Proteaceae family. In Tasmania, it only occurs in the Furneaux , though there is a dubious record on King Island. On mainland Australia though it is quite widespread along the eastern part of the south coast. It is the only Isopogon native to Tasmania, and South Australia.

On Flinders Island, it grows in a few reserves in the northern half of the island in heathland or low growing scrub forest on poor soil dominated by Leptospermum sp. and the occasional Eucalyptus nitida. A significant population is reserved in the Wingaroo Nature Reserve. A recently reserved section of land that contains a number of threatened vegetation types, including at least one that only occurs there. It also contains a number of threatened species, including many species that are only known in Tasmania from the Furneaux group.

Isopogon ceratophyllus is particularly susceptible to disease caused by Phytophthora cinnamomi (cinnamon fungus). So much so that known populations of I. ceratophyllus on the mainland that had been infested by P. cinnamomi have completely disappeared even when other highly susceptible species, such as Xanthorrhea australis, recovered.

As Phytophthera has been recorded in Wingaroo, it seems like bad news for the population of I. ceratophyllus there.

During my 2 visits to the reserve this week, I found a large number of I. ceratophyllus plants on the side of the fire trails I was following, none of which looked healthy. Their growth habit was quite stunted, and a large percentage of their foliage was dead. As I have never seen this plants in person before, I thought at first that this must just be how they look! But a quick check online showed that they grow much larger and don't have a large amount of dead foliage.

Whether the I. ceratophyllus plants looked sickly because of their location (in quite gravelly soil on the side of the fire trail), or because of infection from Phytophthera, I'm not sure. As the Phytophthera in the reserve is known to be along the trails it seems likely to be disease.

I am sure (and hopeful!) that there are healthier individuals deeper in the reserve, but I didn't dare go off track as Flinders has had a lot of rain lately, and the trail was quite muddy. Perfect conditions for spreading Phytophthera!

I hope that a good population of these special plants remain protected from Phytophthera in their quite isolated and hard to reach locations. I am very grateful for the effort gone in to creating reserves like Wingaroo to conserve unique species like the horny cone bush. Without people dedicated to the protection of the unique and intriguing flora of this island we could easily have lost this patch of bush.

Posted on July 15, 2023 05:03 AM by lukemcooo lukemcooo | 3 observations | 0 comments | Leave a comment

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