Investigations into the biology of the four genera of the Fossombroniineae has resulted in several unexpected discoveries, a few of which will be detailed in this presentation. For example, although generally regarded as soil-dwelling, r-selective annuals of disturbed habitats, many species of Fossombronia are actually perennial-stayers and some may even form extensive mats over rocks and roots. Populations are often comprised of single genets which are self-fertile, spore dispersal is local and gene flow between populations is low. Cosmopolitan taxa are anthropogenic and endemics are common. Austrofossombronia comprises several turf-forming species, distributed not only on Antarctic Islands, but also at high elevations around the world. Within the suborder three different mechanisms of drought tolerance and/or avoidance have evolved. These include 1) forming dormant, fleshy stems, with whitened leaves which may regreen on wetting, 2) developing subterranean tubers, and 3) forming endospore-like, endogenous gemmae. Anatomical studies verify that Petalophyllum and Sewardiella form pseudoperianths and shoot calyptrae, but that Fossombronia and Austrofossombronia form a developmentally distinct, analogous structure, here termed a caulocalyx. Preliminary molecular data suggest that Petalophyllum is basal in the suborder and that Fossombronia is derived.

Key words: Austrofossombronia, drought response, Fossombronia, molecular phylogeny, population dynamics, shoot/sporophyte associations