Fig. 2. Cluster analysis based on data for three phenotypes—number of days to first node appearance (with vernalization), number of days to heading (with vernalization), and number of days to heading (without vernalization)—measured at seven photoperiod regimes (8, 10, 12, 14, 16, 18, and 14 h light/24-h period) for the 16 H. vulgare subsp. spontaneum accessions and four H. vulgare subsp. vulgare cultivars described in Table 1.