Vegetation in the coldAntarctic

Usnea Antarctica

Two native flowering plants are widely distributed in the cold-Antarctic. Deschampsia antarctica, a grass, forms low mats, and Coloban-thus quitensis (Caryophyllaceae) occurs in small, compact cushions. Both are most frequent at low altitudes as occasional components of essentially cryptogamic communities on level ground, or more typically on north-or west-facing slopes where the vegetation receives maximum heating from solar radiation. D. antarctica is the more widespread, and usually the more...

Failure in sexual reproduction

In the cases just considered, reproductive phenology of polar mosses follows a normal pattern culminating in release of spores but, as noted earlier, most species fail to produce sporophytes in the more severe polar environments. Spatial separation of male and female plants in dioecious species and imbalance in the production of archegonia and antheridia, with the latter often rare, are the prime causes of a similar failure in some temperate mosses. Other reasons include failure in initiation...

Dispersal and establishment

Dispersal mechanisms Wind is undoubtedly a major factor in the dispersal of bryophytes and lichens. Many species produce spores in the range 5-20 xm in diameter, which are capable of being carried thousands of kilometres by wind. The bryophyte seta ensures that spores of most species are liberated above the laminar boundary layer over the colony, and the wiry nature of the moss seta tends to promote spore release when wind sets the capsules vibrating. Peristome teeth around the capsule mouth,...

Vegetation in the frigidAntarctic

Appressed lichen, and fruticose and foliose lichen subformations The impression presented by ice-free terrain in the frigid-Antarctic is of bare gravel, rock and scree flowering plants are absent and cryptogamic vegetation is only locally prominent. The occasional stands of macrophytic vegetation are referable to the appressed lichen, fruticose and foliose lichen, short moss turf and cushion, and macroscopic alga and cyanobacterium subformations. They are most widespread in coastal regions, but...