The time and duration of flowering in an Adonis multiflora (Ranunculaceae) population

Adonis multiflora is a spring ephemeral herb growing in temperate deciduous forests. To determine the flowering properties of a natural population of A. multiflora, air temperature, flowering time, and flower-falling were monitored from February 2009 to May 2011. The A. multiflora population in this study started flowering in early March and ended it in mid-April. The average flowering duration of a flower was 14.4 days in 2009 and 19.6 days in 2011. The average duration of flower-falling was between 3.4 days and 4.2 days for three years. Cumulative flowering rate (CFR) was correlated with year day (YD), year day index (YDI), and Nuttonson's index (Tn), with correlation coefficients (CC) of over 0.9 at the 1% significance level; CC value between CFR and YD was the largest and that between CFR and YDI was the smallest. However, at the 5% significance level, CFR was closely related with Tn more than any other factors. The CCs between flowering times of two years in each plant were high and significant at 1% level. The YD value of flowering time of a flower was inversely related to its flowering duration significantly for three years. In a given plant, when more flowering started early, the flowering duration was longer. The first flower blossomed on 73.4 YD in 2010 and 78.9 YD in 2011, and remained for 16.7 days in 2009 and 27.4 days in 2011, respectively; the fifth flower developed on 92.5 YD in 2010 and 96.6 YD in 2011, and remained for 8.0 days in 2009 and 14.6 days in 2011. The YD differences between the flowering times of two flowers decreased in the order of inflorescence.