HISTOLOGY AND INHERITANCE OF THE CLOSED FLOWER IN CARTHAMUS TINCTORIUS (COMPOSITAE)

Three different closed flower types were identified in safflower and were classified as arrowhead, bar, and cage. Histological observations revealed that the closed flower condition is caused by a differentiation of epidermal cells into papillae that become interdigited. The primary difference between the three types is the length of the fused edge along the petal lobe. The papillae are pointed and have thickened walls of cutin. Reduced seed set results from changes in the internal environment during microsporogenesis. The expression of each closed flower type is governed by a single gene; the arrowhead, bar, and cage types have, respectively, the genotypes arar, baba, and coca.