From Thomas Meehan   14 June 1880

Dear M^r. Darwin

I am glad you are investigating the movements of plants. It will be worth while to look into the movements of the Stamens in Portulaca Splendens. The fact of the movement formed the subject of my first scientific paper in 1841—Marnock’s Gardener’s Journal,—but I have never been able to get any explanation of the movement.¹ The movement of a leaf of the sensitive plant when touched is always in one and the same direction; but when the stamen of the Portulaca is touched it may go to the right or to the left, upwards or downwards,—and one which you touch now and find moves to the left may move to the right when it is touched again the same day. The power of movement seems to last only one day. There is a similar movement in the stamens of Opuntia Rafinesqui, and Opuntia vulgaris, but so far as I can find always slowly upwards. Portulaca oleracea, a common weed here also has this movement of the Stamens; but the flower is so small that one has to lie flat on the ground with a large magnifier to see it, as the flowers remain open but a very short time.²

A very large number of Scrophulariaceous and Bignoniaceous plants here, which have cloven stigmatic plates, close these lobes when touched. I rarely see any of these but I expect at once to find the motion; but it is remarkable that some species of Orobanchaceae, with similar stigmas, have no motion,— Aphyllon uniflorum, is particularly in mind while writing.³

Sincerely yours as ever | Thomas Meehan