Above the Pinus hartwegii treeline at sharply 4000 m elevation, the alpine vegetation on the Mexican volcanoes is represented by tall tussock grasses and herb fields. In order to improve fodder these grasslands are regularly burned. Rocky outcrops not reached by fire host refugia of herbaceous and scrub flora.

1 - Pico de Orizaba, 5610 m

2 - Tough alpine tussock grasses are regularly burned (4050 m).

3 - Lupinus sp. (Fabaceae), in March, early season (Pico de Orizaba, 4100 m).

4 - Eryngium af. proteiflorum (Apiaceae, left) and small size tussock grasses (right) (Iztaccihuatl, 4000 m). Note the dead leaf curling similar to grass heath in the Alps or New Zealand.

5 - Echevaria sp. (Crassulaceae) (Iztaccihuatl, 4030 m). A common leaf succulent rosette plant which performs crassulacean acid metabolism (CAM).

6 - Mahonia sp. (Berberidaceae), an evergreen shrub (Iztaccihuatl, 4030 m).

29 August 2011
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