Saturday, May 1, 2010

Chthonocephalus pseudevax

Chthonocephalus - etymology:  to have one's head stuck close to or in the ground. Literally meaning (in greek), "soil-head".

Chthonocephalus pseudovax

What a huge name for such a diminutive, unobtrusive plant. This little daisy grows in the more arid regions of Australia, on the impoverished silty clay loams which form the 'red sands' of the region. It is a spring annual (or desert ephemeral), and only really appears after good rainfall during winter months.  The main thing is that it is tiny! The heads (compound capitula) are only 1 - 3 cm in diameter, the plant is little more than a compact plant with a nice tap root, a whorl of leaves and then a compact compound flower head of tiny flowers (the florets).

Until Phil Short's review in 1990, there really was only about three species of Chthonocephlus. Now there are at least seven species, all very cryptic and requiring some detailed microscope work to work out whom is who. Chthonocephlus pseudevax is the common woolly groundhead, and is differentiated from the uncommon C. oldfieldianus by having 3 or 4 lobed florets instead of 5 lobed florets.

Not that you could possibly tell from a mere glance downwards. In fact, you'd be lucky to notice these plants at all if you weren't scanning the ground with a careful eye.

So next time you are walking among the wildflowers in the right area (i.e. inland Australia on red silty clay soils) - look down for Chthonocephalus - the little plant with the ridiculously big name.

Short, Philip S. (1990). A revision of the genus Chthonocephalus Steetz. (Asteraceae : Inuleae : Gnaphaliinae). Muelleria Vol. 7:225-238. National Herbarium and Botanic Gardens. Melbourne.

Addendum - I suspect that the image on Florabase website is not C. pseudevax but C. viscosus. Given that the premises are about to move, now is not a good time to tell them that that image and its voucher needs reconsideration.

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