Saturday, April 18, 2015

Botany post #199: Dawsonia superba

Dawsonia superba (Polytrichaceae), Melbourne Museum, just two weeks ago. The Polytrichaceae have always been my favourite moss family, perhaps because they are the mosses that have got closest to becoming vascular plants; you just have to appreciate somebody who tries to shoulder into a niche space already occupied by hundreds of thousands of seed plant and fern species. Polytrichaceae have simple vascular bundles in their stems and rather complex leaves with lamellae on top. And thanks to these adaptations they can also become quite large.

Dawsonia is the largest of them all and certainly the moss that produces the most robust leaves and the tallest living stems. (Peat mosses - Sphagnum - can form massive spongy cushions but everything but the uppermost layers is dead.) Most people would not recognise it as a moss; they are often taken for vascular plants, for pine seedlings for example.

Having only ever seen it as a herbarium specimen at university (in an accordingly oversized cryptbox), I was extremely gratified to see a living colony in the Melbourne Museum's forest gallery when we visited the city over Easter.

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