A Taxonomist's Experience with Hybrids in the Wild

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Abstract
Hybridization in the wild seems necessary to account for the enormous variation found in Amelanchier in N. Amer. Here, after much sorting, it was found that 6 spp. existed which, if crossing were assumed, would account for the large mass of remaining specimens. The same situation was found in, 2 groups of asters studied. These hybrids were apparently more numerous in the herbarium than in nature, as the botanist is inclined to collect unusual forms. Crossing seems to occur sporadically in nature. The reason is not clear, but it is possibly due to disturbance in the environment, as illustrated by Amelanchier, Rubus, and Crataegus. How the disturbance would operate is discussed. Possibly belated or precocious flowering of individuals of 2 spp., due to the disturbance, might account for the crossing. The stability of hybrids and their relation to the problem of the origin of species is interesting. While geneticists have found that some hybrids breed true, this is doubtfully frequent enough to account for the number and morphological diversity of species in nature. Natural hybrids seem to be temporary and to soon disappear, leaving the fundamental species, in eastern America at least, to stretch back through the ages to the glacial period or beyond. What causes the disappearance of hybrids is not clear. From the writer''s observation there is little to support the theory that species in any number have arisen through hybridization. In designating hybrids taxonomically the method preferred is to cite the names of the 2 parent species separated by the letter X and not to coin a new specific name, as the latter method would confuse the evanescent hybrids with the old fundamental species.

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