The Different Forms of Flowers on Plants of the Same Species

by Charles Darwin

PLANT 29.

This long-styled plant was legitimately fertilised during the unfavourable season of 1864, in the manner described under Number 26, and yielded an average, from ten capsules, of 84.6 seeds, with a maximum of 132 and a minimum of 47, thus attaining to 91 per cent of the normal fertility. During the highly favourable season of 1866, when fertilised in the manner described under Number 26, it yielded an average, from nine capsules (one poor capsule having been excluded), of 100 seeds, with a maximum of 121 and a minimum of 77. This plant thus exceeded the normal standard, and produced 107 per cent of seeds. In both sets of anthers there were a good many bad and shrivelled pollen-grains, but not so many as in the last-described plant.

Plant 30.

This long-styled plant was legitimately fertilised during 1866 in the manner described under Number 26, and yielded an average, from eight capsules, of 94 seeds, with a maximum of 106 and a minimum of 66; so that it exceeded the normal standard, yielding 101 per cent of seeds.

Plant 31.

Some flowers on this long-styled plant were artificially and legitimately fertilised by one of its brother illegitimate mid-styled plants; and five capsules yielded an average of 90.6 seeds, with a maximum of 97 and a minimum of 79. Hence, as far as can be judged from so few capsules, this plant attained, under these favourable circumstances, 98 per cent of the normal standard.]

CLASS 7. ILLEGITIMATE PLANTS RAISED FROM MID-STYLED PARENTS FERTILISED WITH POLLEN FROM THE LONGEST STAMENS OF THE SHORT-STYLED FORM.

It was shown in the last chapter that the union from which these illegitimate plants were raised is far more fertile than any other illegitimate union; for the mid-styled parent, when thus fertilised, yielded an average (all very poor capsules being excluded) of 102.8 seeds, with a maximum of 130; and the seedlings in the present class likewise have their fertility not at all lessened. Forty plants were raised; and these attained their full height and were covered with seed-capsules. Nor did I observe any contabescent anthers. It deserves, also, particular notice that these plants, differently from what occurred in any of the previous classes, consisted of all three forms, namely, eighteen short-styled, fourteen long-styled, and eight mid-styled plants. As these plants were so fertile, I counted the seeds only in the two following cases.