Variation of the number of sepals in Anemone nemorosa

G. UDNY YULE
1902 Biometrika  
IT ia a question of some interest how far local race* of plants vary from year to year. An abnormal characteristic, or a larger proportion of abnormal individuals, may be exhibited at some one time by one local race ns compared with another, but unless the same race be reobserved, it cannot be certain that the abnormality ia not merely a temporary condition, doe to an unusually wet or dry season, or to the fact that the different races compared were observed at different times in the season.
more » ... s in the season. With individuals so largely subject to external influences as plants a good deal of caution must be used in drawing conclusions. In the spring of 1898, between the 20th and 23rd of April, I counted the number of sepals on three different series of Anemone nemorota in the neighbourhood of Bookhani, Surrey. The three places from which they were taken are within a mile or two of each other, and on the same clay subsoil. A was a copse by Banks Common, Effingham; the underwood had been recently out, so the place was fairly exposed, there being few large trees. B was a spot in one of the Eastwick woods ; the underwood had not bqen cut for a lung time, BO it was close growing and the ground very sheltered. C was a narrow strip of copse, only a few yards wide, between two fields in the parish of Little Bookham. It sloped slightly down a hill. The underwood was low, about a year old, so the situation may be called exposed. The sepals were counted on the spot, a thousand being taken in each place. The flower is a delicate one, and it is necessary to take a good deal of care not to count specimens that have lost one or more sepals; I never admitted a flower that dropped a sepal on being shaken or blown. The frequencies are given in the first three columns of Table I . B exhibits the largest proportion of sixes and the least variability, C the lowest proportion of sixes and the. greatest variability, A is intermediate. A fortnight later the strip of copse C was revisited. It was late in the season, the anemones were half over and the 600 which were counted nearly cleared the strip. The frequencies per 1000 are given in Column 4. It will be seen that the distribution is quite different to that of Column 3 ; flowers with five and six sepals are more frequent, with seven or more sepals less frequent, than earlier in the season. The S.D. is however sensibly the some, being in both cases markedly higher for C than for either A or B. The intervening fortnight had been wet. In the spring of 1899 the two places A and O were again visited and 500 flowera counted at each; it will be noted that the visit was made nearly a fortnight earlier than in the preceding year. The frequencies per 1000 are given in Columns 5 and 6. The distribution for A resembles
doi:10.1093/biomet/1.3.307 fatcat:3s5ce7yhsjcmxo263lcgsrkynq