Geographic distribution and genetic resources of Dactylis in Galicia (northwest Spain)

Three Dactylis glomerata subspecies can occur in Galicia (Spain): subsp. glomerata, subsp. izcoi and subsp. marina. The second includes diploid and tetraploid populations adapted to acid soils. The third subspecies comprises natural tetraploid populations mainly on sea cliffs, with high digestibility. Dactylis taxonomy is difficult due to the existence of different ploidy levels and to free hybridization at the tetraploid level. This difficulty increases in Galicia, where there is a rich flora with relics and hybrids. The advance of human technology makes necessary the collection of natural Dactylis resources. In this paper, Dactylis distribution in Galicia is described. Tetraploid populations from subsp. izcoi have a wider ecological range than diploids (Galician diploid). These diploids and the subsp. marina are more widespread than formerly recognized. Morphologically, subsp. glomerata and izcoi are more similar than hitherto reported. It is suggested that the subspecies are adapted ecotypes which hybridize. They are useful genetic resources for pasciculture on acid soils and agroforestry.