The genus Dactylis L. in Italy. 1. The tetraploid entities

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Abstract
Dactylis L. is present in Italy with some diploid (2n = 14) entities and a broad complex of tetraploids (2n = 28). The latter are the large majority of Italian populations. A biometrical and biochemical analysis on herbarium material and on specimens sampled from natural populations, showed that the characters concerning size and shape of the inflorescence form a continuous series, are strongly correlated among themselves, but do not correlate with other characters. The presence and dimensions of lobes on the lemma is variable on the same specimens and is more frequent on the western side of the Apennines than on the eastern side. The presence of papillae and of a smooth margin on the leaves have a weak mutual correlation, are more frequent in western populations, and are exclusive of coastal stands. Other characters vary irregularly, and do not correlate with the characters above. Protein characters also present some differences among the samples studies, but do not correlate with morphological characters, nor with geographical or ecological factors. Factor Analysis and Cluster Analysis resulted in a dispersion of the specimens under study along the main axes, without formation of discrete clusters. It is concluded that the complex of Italian tetraploid entities forms one hologamodeme, where characters or groups of characters vary along mutually independent clines. All italian tetraploids are ranked under D. glomerata subsp. glomerata. To account for the most remarkable extremes of phenotypic variation, two varieties are recognized, besides var. glomerata, i.e. var. italica Schreber (= D. hispanica auct.fl.ital.) and var. marina (Borrill) stat. et comb. nov.