A Comparison of the Flowering and Branching Control Systems in Lathyrus odoratus L. and Pisum sativum L.

In the sweet pea (Lathyrus odoratus L.) the difference in floweringbehaviour between photoperiodic (long-day) and day-neutral cultivars appears to be due to a difference in their ability to produce a graft-transmissible floral inhibitor. The flowering control systems in the sweet pea and the garden pea (Pisum sativum L.) appear to be very similar on the basis of inter-generic graft results. It is suggested that the major flowering genes Dn* in L. odoratus and Sn and Dne in P. sativum control steps in a biochemical pathway common to these two species (which are related at the tribal level) and that the product of this pathway inhibits flowering and promotes outgrowth of basal laterals in both species.