Entwicklungstendenzen blütenökologischer Merkmale bei Plantago

Abstract

Adaptations concerning pollination ecology were studied in 5 European species (14 populations) of Plantago from 4 sections of the genus. The following quantitative characters were studied: anther length, anther width, pollen grains per anther, stigma length and pollen diameter. In Plantago these characters form a complex, which is typically for anemophily. This syndrom of anemophily (F aegri and Van Der P ijl 1971) allows to calculate the number of pollen grains per anther (difficult to determine) from anther length (AL), stigma length (GL) and pollen diameter (PD) by using the regression (equation: y = -34, 925 + 20, 547 AL + 0, 794 GL + 0, 353 PD (B = 0, 914). Correlations between floral characters are given. The evolution within Plantago went from entomophily to anemophily, with the result of large anthers with many pollen grains, large stigmas and little pollen grains, P. media and to some extend P. maritima have maintained characters of entomophily and that’s why they are often pollinated by insects. A striking evolution into the direction of anemophily show p, lanceolata and some populations of P. media (especially large anthers with many pollen grains). In the other species studied, P. major, P. coronopus, P. maritima and in some populations of P. media , a tendency to autogamy together with the reduction of characters of anemophily can be observed. These evolutionary trends of adaptations to pollination ecology and breeding system can be demonstrated with the above mentioned characters but best of all with the number of pollen grains per anther.