Are there heteromorphic sex chromosomes in spinach (Spinacia oleracea L.)?

Summary Four varieties and two introductions of Spinacia oleracea are cytologically studied in order to determine whether there is a heteromorphic sex chromosome pair in any of the sexes. It is observed that in one and the same preparation, and regardless of the sex of the plants, different cells had homomorphic and heteromorphic condition for chromosome 1 pair. It is concluded that as a result of differential contraction of chromosomes, the arm ratios and total lengths may vary, and give a distorted impression of certain pair of chromosomes. The absence of heteromorphic pair is confirmed in male and intersex plants by meiotic studies.