Adaptation to Habitat in a Group of Annual Plants

Abstract

Arabidopsis thaliana, Arenaria serpyllifolia, Cardamine hirsuta, Cerastium semidecandrum, Draba muralis, L. Erophila verna, Hornungia petraea, Myosotis ramosissima, Saxifraga tridactylites and Veronica arvensis form a distinct annual community on shallow soils with a southerly aspect in Derbyshire. They have a main distribution in Mediterranean and sub-Mediterranean areas and are found in similar habitats in much of western Europe. Their seeds germinate in the autumn and they flower in spring. The seeds need to after-ripen for about 12 weeks after shedding before good germination is possible; germination is usually better in light than in darkness. These and other factors prevent germination until autumn when soil moisture level determines the exact time. None of the species can flower without experiencing a period of months below 10[degree] to 15oC, so preventing autumn flowering. Seeds of Arabidopsis thaliana and Hornungia petraea may be vernalized, inducing flowering in any subsequent temperature condition.