Experiments which were made with several members of this family led to the result that the genus Pisum was found to possess the necessary qualifications. Some thoroughly distinct forms of this genus possess characters which are constant, and easily and certainly recognizable, and when their hybrids are mutually crossed they yield perfectly fertile progeny. Furthermore, a disturbance through foreign pollen cannot easily occur, since the fertilizing organs are closely packed inside the keel and the anthers burst within the bud, so that the stigma becomes covered with pollen even before the flower opens. This circumstance is especially important. As additional advantages worth mentioning, there may be cited the easy culture of these plants in the open ground and in pots, and also their relatively short period of growth.
Artificial fertilization is certainly a somewhat elaborate process, but nearly always succeeds.
For this purpose the bud is opened before it is perfectly developed, the keel is removed, and each stamen carefully extracted by means of forceps, after which the stigma can at once be dusted over with the foreign pollen. In the case of one variety there were noticed, among a larger number of plants all alike, a few forms which were markedly different. For fertilization 22 of these were selected and cultivated during the whole period of the experiments. They remained constant without any exception. Their systematic classification is difficult and uncertain.