SO-CALLED (by me) MALE plant. Pistil much shorter than stamens; stigma rather smooth,—POLLEN GRAINS LARGE, throat of corolla short.
SO-CALLED FEMALE plant. Pistil much longer than stamens, stigma rougher, POLLEN-GRAINS SMALLER,—throat of corolla long.
I have marked a lot of plants, and expected to find the so-called male plant barren; but judging from the feel of the capsules, this is not the case, and I am very much surprised at the difference in the size of the pollen... If it should prove that the so-called male plants produce less seed than the so-called females, what a beautiful case of gradation from hermaphrodite to unisexual condition it will be! If they produce about equal number of seed, how perplexing it will be.
CHARLES DARWIN TO J.D. HOOKER. Down, December 17 [1860?].
... I have just been ordering a photograph of myself for a friend; and have ordered one for you, and for heaven's sake oblige me, and burn that now hanging up in your room.—It makes me look atrociously wicked.
... In the spring I must get you to look for long pistils and short pistils in the rarer species of Primula and in some allied Genera. It holds with P. Sinensis. You remember all the fuss I made on this subject last spring; well, the other day at last I had time to weigh the seeds, and by Jove the plants of primroses and cowslip with short pistils and large grained pollen (Thus the plants which he imagined to be tending towards a male condition were more productive than the supposed females.) are rather more fertile than those with long pistils, and small-grained pollen. I find that they require the action of insects to set them, and I never will believe that these differences are without some meaning.
Some of my experiments lead me to suspect that the large-grained pollen suits the long pistils and the small-grained pollen suits the short pistils; but I am determined to see if I cannot make out the mystery next spring.
How does your book on plants brew in your mind? Have you begun it?...
Remember me most kindly to Oliver. He must be astonished at not having a string of questions, I fear he will get out of practice!
[The Primula-work was finished in the autumn of 1861, and on November 8th he wrote to Sir J.D. Hooker:—