SPONTANEOUS HYBRIDIZATION OF THE PUTATIVE ANCESTORS OF THE ALLOTETRAPLOID POA ANNUA

Spontaneous hybrids between the two diploids Poa infirma Kunth and P. supina Schrader were obtained at the rate of 0.2%. No reciprocal mater nal effect was observed. Almost all hybrids survived, grew normally bu t were sterile. Hybrids were diploid, and resembled in morphology the tetraploid P. annua L. (annual meadow grass). In their isozymes, they showed additivity of the parental patterns, and were very similar to t hose found in P. annua populations. The ease with which hybrids were o btained and the similarity of their morphological and isozyme pattern to P. annua suggest that the two diploid species are closely related t o the allotetraploid species, and are perhaps its parent species.