Flowering Responses in a Strain of Orobanche minor

Abstract

An interesting case of the dependence of flowering on length of day has been found in Orobanche minor growing on red clover. In the first place, data obtained by one of us (P. S. N.) suggested that the time of flowering of this parasitic plant was synchronous with that of the host plant, and was to a large extent independent of the sowing date of the parasite. Late-flowering Montgomeryshire red clover seed was sown at six-weekly intervals from November 1945 until June 1946; Orobanche seed was added, through glass tubes already in position in the soil, in some treatments concurrently with the clover seed and in others at each subsequent six weeks interval. The November-, January- and February-sown clovers all flowered in early August, the Orobanche appearing in August, September and October, almost independently of the time of sowing of the parasite. The April-, May- and June-sown clovers flowered September to October, and the Orobanche attached to them appeared at about the same times.