To J. D. Hooker   17 September 1870

Sir J Lubbock’s woods were planted about 30 years ago. When Land here is no longer cultivated it becomes thickly covered with coarse vegetation, and I have never seen charlock growing in such places.¹ This summer Sir. J. L. had a space of about 2 ft around the choicer shrubs, cleared of herbage and deeply forked, on both sides of the long middle drive. In 49 cases (i.e. in about three fourths of the cleared spaces,) I observed yesterday one or several charlock plants growing. The wood-covered slope consistes of the same soil throughout; but down the middle, and across the drive, there are plain traces of an old hedge, shewing that two large fields were originally enclosed and planted, and probably were under different culture. Now on both sides of this line the ground has been forked round the shrubs; but all the charlock plants that I saw on the 49 spaces were on one side of this line; and literally not one charlock plant on the forked spaces on the other side of the line, and therefore in what was formerly a different field. Considering more especially this latter fact, and that charlock seed has no pulp for birds and cannot easily be blown about, it seems to me almost certain that the seeds have lain in the ground for nearly 30 years.²

C. Darwin

Sept 17. 1870

In the parallel case observed in my own little wood & formerly described in Gard: Chronicle, the interval since planting had been only, I think, 12 or 14 years.—³