Fig. 1. Relationships between (A) age at onset of dormancy and (B) proportions of flowering plants (%) and aridity (mean annual precipitation) at the site of origin of the populations of P. bulbosa. Data are population means ± s.e. Numbers indicate population codes (see Table 1). A, Age at onset of dormancy (days from sprouting) was determined in daughter plants grown in the phytotron under 16 h days, 22/16 °C (day/night). Regression y = 57·7 + 0·07x, r = 0·600, P < 0·02, d.f = 14. B, Proportions of flowering parental plants were determined under natural conditions (net‐house). Regression y = 92·9 – 0·11x, r = –0·596, P < 0·02, d.f = 14.