278 ADAPTATIONS AMONG ALPINE PLANTS 



whole of the Alpine Grasses, Kushes, and Sedges, 

 and some others. In such plants the individual 

 flowers are nearly always small and inconspicuous, 

 and either devoid of calyx and corolla, or possess 

 a very reduced, inconspicuous perianth. Another 

 striking feature of wind-pollinated plants is that the 

 flowers are often aggregated into dense clusters, 

 or inflorescences. 



Self-fertilisation — the fertilisation of the ovules of 

 a flower by pollen derived from the anthers of the 

 same flower — is also common, and the seeds that 

 result may be either quite fertile or abortive. 

 Many flowers, which are normally cross-pollinated 

 by insect agency, may, if no insect visits the flower 

 or no foreign pollen is brought to their stigmas, 

 fertilise themselves at the end of the flowering stage. 

 Some flowers possess special adaptations to ensure 

 self-fertilisation, if cross-pollination fails. 



Some plants produce flowers which never open 

 — cleistogamous, as they are called botanically — in 

 addition to ordinary flowers. This j^henomenon is 

 not very frequent in the Alps, though it is sometimes 

 to be found in the case of certain Gentians, Gentiana 

 tenella, Eottb., and G, campestris, Linn., and in the 

 Wood Sorrel. As a rule, such cleistogamous flowers 

 in the Alps are of quite normal structure, though, 

 either through lack of sufficient light or warmth, they 

 never open. In the Lowlands some plants produce 

 flowers which never open under any circumstances, 

 such as certain Violets and Dead Nettles (e,g., 



