The morphological characteristics, fertility and in vitro germination of natural tetraploid red clover (Trifolium pratense L.) pollen were examined as well as the characteristics of pollen tubes and callose formation. Pollen grains of red clover are tricolporate and usually the germination of pollen is monosphonic. | In vitro pollen germination and pollen tube characteristics in tetraploid red clover (Trifolium pratense L.)