Number of floral organs in Circaeaster agrestis (Circaeasteraceae) and possible homeosis among floral organs

98.9% of 5092 flowers from 1041 individuals of Circaeaster agrestis have five floral organs, the formula is P(3)A(1)G(1) (73.13%), P(2)A(2)G(1) (25.59%), and P(2)A(1)G(2) (0.22%). Only 0.4% of the flowers have six floral organs and the formula is P(3)A(1)G(2) (20 flowers) or P(3)A(2)G(1) (one flower). All these flowers have one vascular bundle in the pedicel and were considered to be normal ones. There are 33 flowers (0.65%) with six or more floral organs and two vascular bundles in the pedicel and we found traces of fusion of different degree of two flowers into one. These flowers were considered as abnormal. Therefore the normal number of floral organs of C. agrestis is five and occasionally six, and the floral formulas are P(3)A(1)G(1) or P(2)A(2)G(1), sometimes P(2)A(1)G(2), and occasionally P(3)A(1)G(1) or P(3)A(2)G(1). A tepal in P(3)A(1)G(1) may be replaced by a stamen in P(2)A(2)G(1) or by a carpel in P(2)A(1)G(2) or in reverse. A carpel in P(3)A(1)G(2) may be replaced by a stamen in P(3)A(2)G(1) or in reverse. We hypothesize that there are two possibilities for the number of the floral organs to be five (six), the result of reduction from P(3)A(2)G(2), or there exists homeosis among floral organs.