Red clover is the most commonly used forage legume in the Nordic region. It occurs across most of the area, though only sparsely in the northernmost and mountain areas and in Iceland. The species displays a large diversity in the size and colour of the flower, the height and the plant’s growth habit, the occurrence and the spread of a white spot on the top of the leaves, the degree of hairiness and many other characters. Nevertheless, it is not difficult to recognize the species by its light to dark pink flower head and the often quite sturdy plants. The cousin, Zigzag Clover (Trifolium medium L.), can look very similar but has a less dense flower head and, in particular, a small stalk between the head and the top leaf. 

The species is cross-pollinated and usually diploid, i.e. has a single set with 14 chromosome pairs. Both naturally, but also through plant breeding, tetraploids have developed a double set of chromosomes. These varieties are generally larger than the diploids which is an advantage in forage production. One problem, however, has been the seed production. Red clover is dependent on bees and bumblebees for their pollination, and especially in tetraploid varieties, which have larger flowers, the bumble bees with their longer tongues are absolutely necessary. Many wild bumblebee species have long tongues and therefore management actions that benefit the bumblebees will also benefit the seed set in red clover, as well as the seed and fruit production in other species in the area. 

Red clover has been cultivated for a long time. Initially the wild form was cultivated, but as our ancestors continued to harvest it for hay, a slow adaptation to the new growing conditions took place. Earlier generations farmers have probably selected plants with superior cultivation properties and let them produce seeds in appropriate locations. The early cultivars were based on a selection of plants from local populations/landraces. After a numbers of years of cultivation, new selections had to be made at intervals since the cultivated material mixed with local wild populations. Red clover ‘Bjursele’ is an old landrace from Västerbotten in Sweden and has been cultivated for a very long time, the use of which has continued into modern times. The terms early, intermediate and late refers to the development time of the cultivar and different types are suited to different parts of the Nordic region. 

You can read more about the Swedish seed production of red clover at the homepage “Svensk raps”. Here you can also find information about the importance of bees and bumblebees for pollination – if you did not already know that!  

Text: Jens Weibull (translated and adapted by Anna Palmé) 

Links (in Swedish): 

Rödklöver

Om inte pollinatörerna gör det…