The Different Forms of Flowers on Plants of the Same Species Part 15

Long-styled by pollen of longest stamens of mid-styled. Legitimate union : 21 : 21 : 12.0.

Long-styled by pollen of own and own-form mid-length stamens. Illegitimate union : 40 : 2 : 5.5.

Long-styled by pollen of own and own-form shortest stamens. Illegitimate union : 26 : 0 : 0.

Long-styled by pollen of shortest stamens of short-styled. Illegitimate union : 16 : 1 : 1.

Long-styled by pollen of shortest stamens of mid-styled. Illegitimate union : 9 : 0 : 0.

Mid-styled by pollen of mid-length stamens of long-styled. Legitimate union : 38 : 38 : 11.3.

Mid-styled by pollen of mid-length stamens of short-styled. Legitimate union : 23 : 23 : 10.4.

Mid-styled by pollen of own and own-form longest stamens. Illegitimate union : 52 : 0 : 0.

Mid-styled by pollen of own and own-form shortest stamens. Illegitimate union : 30 : 1 : 6.

Mid-styled by pollen of shortest stamens of long-styled. Illegitimate union : 16 : 0 : 0.

Mid-styled by pollen of longest stamens of short-styled. Illegitimate union : 16 : 2 : 2.5.

Short-styled by pollen of shortest stamens of long-styled. Legitimate union: 18 : 18 : 11.0.

Short-styled by pollen of shortest stamens of mid-styled. Legitimate union: 10 : 10 : 11.3.

Short-styled by pollen of own and own-form longest stamens. Illegitimate union : 21 : 0 : 0.

Short-styled by pollen of own and own-form mid-length stamens. Illegitimate union : 22 : 0 : 0.

Short-styled by pollen of longest stamens of mid-styled. Illegitimate union: 4 : 0 : 0.

Short-styled by pollen of mid-length stamens of long-styled. Illegitimate union: 3 : 0 : 0.

We here have the remarkable result that every one of 138 legitimately fertilised flowers on the three forms yielded capsules, containing on an average 11.33 seeds. Whilst of the 255 illegitimately fertilised flowers, only 6 yielded capsules, which contained 3.83 seeds on an average. Therefore the fertility of the six legitimate to that of the twelve illegitimate unions, as judged by the proportion of flowers that yielded capsules, is as 100 to 2, and as judged by the average number of seeds per capsule as 100 to 34. It may be added that some plants which were protected by nets did not spontaneously produce any fruit; nor did one which was left uncovered by itself and was visited by bees. On the other hand, scarcely a single flower on some uncovered plants of the three forms growing near together failed to produce fruit.

Oxalis Regnelli.

This species bears white flowers and inhabits Southern Brazil. Hildebrand says that the stigma of the long-styled form is somewhat larger than that of the mid- styled, and this than that of the short-styled. The pistil of the latter is clothed with a few hairs, whilst it is very hairy in the other two forms. The diameter of the pollen-grains from both sets of the longest stamens equals 9 divisions of the micrometer,--that from the mid-length stamens of the long- styled form between 8 and 9, and of the short-styled 8,--and that from the shortest stamens of both sets 7. So that the extreme difference in diameter is as 9 to 7 or as 100 to 78. The experiments made by Hildebrand, which are not so numerous as in the last case, are given in Table 4.28 in the same manner as before.

TABLE 4.28. Oxalis Regnelli (from Hildebrand).

Column 1: Nature of the Union.

Column 2: Number of Flowers fertilised.

Column 3: Number of Capsules produced.

Column 4: Average Number of Seeds per Capsule.

Long-styled by pollen of longest stamens of short-styled. Legitimate union : 6 : 6 : 10.1.

Long-styled by pollen of longest stamens of mid-styled. Legitimate union : 5 : 5 : 10.6.

Long-styled by pollen of own mid-length stamens. Illegitimate union : 4 : 0 : 0.

Long-styled by pollen of own shortest stamens. Illegitimate union : 1 : 0 : 0.

Mid-styled by pollen of mid-length stamens of short-styled. Legitimate union : 9 : 9 : 10.4.

Mid-styled by pollen of mid-length stamens of long-styled. Legitimate union : 10 : 10 : 10.1.

Mid-styled by pollen of own longest stamens. Illegitimate union : 9 : 0 : 0.

Mid-styled by pollen of own shortest stamens. Illegitimate union : 2 : 0 : 0.

Mid-styled by pollen of longest stamens of short-styled. Illegitimate union : 1 : 0 : 0.

Short-styled by pollen of shortest stamens of mid-styled. Legitimate union: 9 : 9 : 10.6.

Short-styled by pollen of shortest stamens of long-styled. Legitimate union: 2 : 2 : 9.5.

Short-styled by pollen of own mid-length stamens. Illegitimate union : 12 : 0 : 0.

Short-styled by pollen of own longest stamens. Illegitimate union : 9 : 0 : 0.

Short-styled by pollen of mid-length stamens of long-styled. Illegitimate union: 1 : 0 : 0.

The results are nearly the same as in the last case, but more striking; for 41 flowers belonging to the three forms fertilised legitimately all yielded capsules, containing on an average 10.31 seeds; whilst 39 flowers fertilised illegitimately did not yield a single capsule or seed. Therefore the fertility of the six legitimate to that of the several illegitimate unions, as judged both by the proportion of flowers which yielded capsules and by the average number of contained seeds, is as 100 to 0.

Oxalis speciosa.

This species, which bears pink flowers, was introduced from the Cape of Good Hope. A sketch of the reproductive organs of the three forms (Figure 4.11) has already been given. The stigma of the long-styled form (with the papillae on its surface included) is twice as large as that of the short-styled, and that of the mid-styled intermediate in size. The pollen-grains from the stamens in the three forms are in their longer diameters as follows:--

Table 4.c. Oxalis speciosa. Diameters of pollen-grains in divisions of the micrometer.

Column 1: Source of Pollen-grains.

Column 2: Minimum diameter.

Column 3: Maximum diameter.

From the: Longest stamens of short-styled form : 15 to 16.

Mid-length stamens of short-styled form : 12 to 13.

Longest stamens of mid-styled form : 16.

Shortest stamens of mid-styled form : 11 to 12.

Mid-length stamens of long-styled form : 14.

Shortest stamens of long-styled form : 12.

Therefore the extreme difference in diameter is as 16 to 11, or as 100 to 69; but as the measurements were taken at different times, they are probably only approximately accurate. The results of my experiments in fertilising the three forms are given in Table 4.29.

Table 4.29. Oxalis speciosa.

Column 1: Nature of the Union.