Pot 1 : 32 6/8 : 25. Pot 1 : 20 : 18 6/8.
Pot 2 : 32 3/8 : 20 6/8. Pot 2 : 24 4/8 : 19 4/8.
Pot 3 : 29 4/8 : 25. Pot 3 : 28 : 18.
Total : 167.13 : 127.00.
It may be here seen that each of the six tallest crossed plants exceeds in height its self-fertilised opponent; the former averaged 27.85 inches, whilst the six tallest self-fertilised plants averaged 21.16 inches; or as 100 to 76. In all three pots the first plant which flowered was a crossed one. All the crossed plants together produced 409 flowers, whilst all the self-fertilised together produced only 232 flowers; or as 100 to 57. So that the crossed plants in this respect were far more productive than the self-fertilised.
Origanum vulgare.
This plant exists, according to H. Muller, under two forms; one hermaphrodite and strongly proterandrous, so that it is almost certain to be fertilised by pollen from another flower; the other form is exclusively female, has a smaller corolla, and must of course be fertilised by pollen from a distinct plant in order to yield any seeds. The plants on which I experimented were hermaphrodites; they had been cultivated for a long period as a pot-herb in my kitchen garden, and were, like so many long-cultivated plants, extremely sterile. As I felt doubtful about the specific name I sent specimens to Kew, and was assured that the species was Origanum vulgare. My plants formed one great clump, and had evidently spread from a single root by stolons. In a strict sense, therefore, they all belonged to the same individual. My object in experimenting on them was, firstly, to ascertain whether crossing flowers borne by plants having distinct roots, but all derived asexually from the same individual, would be in any respect more advantageous than self-fertilisation; and, secondly, to raise for future trial seedlings which would constitute really distinct individuals. Several plants in the above clump were covered by a net, and about two dozen seeds (many of which, however, were small and withered) were obtained from the flowers thus spontaneously self-fertilised. The remainder of the plants were left uncovered and were incessantly visited by bees, so that they were doubtless crossed by them. These exposed plants yielded rather more and finer seed (but still very few) than did the covered plants. The two lots of seeds thus obtained were sown on opposite sides of two pots; the seedlings were carefully observed from their first growth to maturity, but they did not differ at any period in height or in vigour, the importance of which latter observation we shall presently see. When fully grown, the tallest crossed plant in one pot was a very little taller than the tallest self-fertilised plant on the opposite side, and in the other pot exactly the reverse occurred. So that the two lots were in fact equal; and a cross of this kind did no more good than crossing two flowers on the same plant of Ipomoea or Mimulus.
The plants were turned out of the two pots without being disturbed and planted in the open ground, in order that they might grow more vigorously. In the following summer all the self-fertilised and some of the quasi-crossed plants were covered by a net. Many flowers on the latter were crossed by me with pollen from a distinct plant, and others were left to be crossed by the bees. These quasi-crossed plants produced rather more seed than did the original ones in the great clump when left to the action of the bees. Many flowers on the self-fertilised plants were artificially self-fertilised, and others were allowed to fertilise themselves spontaneously under the net, but they yielded altogether very few seeds. These two lots of seeds—the product of a cross between distinct seedlings, instead of as in the last case between plants multiplied by stolons, and the product of self-fertilised flowers—were allowed to germinate on bare sand, and several equal pairs were planted on opposite sides of two LARGE pots. At a very early age the crossed plants showed some superiority over the self-fertilised, which was ever afterwards retained. When the plants were fully grown, the two tallest crossed and the two tallest self-fertilised plants in each pot were measured, as shown in Table 3/28. I regret that from want of time I did not measure all the pairs; but the tallest on each side seemed fairly to represent the average difference between the two lots.
TABLE 3/28. Origanum vulgare.
Heights of Plants measured in inches.