Agromorphological characterization, cyanogenesis and productivity of accessions of white clover (Trifolium repens L.) collected in Northern Spain

White clover (Trifolium repens L.) is an essential element of sustainable livestock systems in temperate climates because of its adaptability to a range of management and soil fertility conditions. The performance of 15 accessions of white clover collected in northern Spain, and of two cultivars, the medium-leaved Huia and the large-leaved California, grown as spaced plants in Galicia, and in sward plots in Asturias was compared over a period of two years. The data obtained were reduced to two principal components that cumulatively explained 92.4% of the total variance. Cluster analysis identified three groups of accessions that described 71% of the phenotypic variation among accessions. One group of five accessions collected from upland sites was characterized by low dry matter yield, low height, reduced plant spread, short petioles, small leaves and thin stolons. This group can be defined as small-leaved and of interest for gardening. Another group, composed only by the cv. California and the cv. Huia, was characterized by high plant spread and height, long wide leaves and thick petioles and stolons; dry matter yields were similar to those of the first group. The last group, which includes ten accessions collected from low and medium altitude sites, had the highest dry matter yields and intermediate morphological character between the previous groups. This group can be defined as medium-leaved and of interest for grazing and/or cutting.