To James Torbitt   20 March 1878

My dear Sir

The subject which you discuss in your last letter is a very difficult and doubtful one.¹ Your view may be correct and I think it would be quite worth while to keep the subject before you and after more observations and especially experiments to publish on it. It has been recorded by Knight that the first flowers produced by some young trees are sterile, and I have occasionally found the first flowers on herbaceous plants sterile.² As you no doubt know there are a multitude of cases of plants which have been long propagated by roots, stolons &c the flowers of which never set a seed. No botanist has seen a seed of the horse radish, the wild Ranunculus ficaria rarely produces seed.³ Again there are many cases of abnormally succulent fruits, such as pine-apples, bananas &c. which rarely or never set seeds. It appears therefore that whenever much nutriment is drawn to the organs of vegetation or the fruit, seeds fail. As the potato is propagated by tubers, this may be and probably is one chief cause of its frequent sterility. I remember hearing before the arrival of the potato fungus that some varieties flowered profusely and others scantily, and it seems to me doubtful whether all such cases can be accounted for by differences of age; but rather by innate different constitutions. I have given many facts on the sterility of plants in Ch. 18, Vol. II, 2nd Edit. in my Var. of Animals and Plants under Dom.⁴ In former years I should have been very glad to have observed the seedlings from the dwarf var.;⁵ but I am growing old and cannot attend to different subjects; and now have my hands more than full of work. If at any time I can give you information I shall feel it a pleasure to do so, but otherwise I wish to avoid as much as possible extraneous work. I have not yet heard from Mr. Farrer. I forwarded the testimonials to Mr. Caird.⁶

My dear Sir, | Yours faithfully | Charles Darwin