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Show I 06 HETEROSTYLED DIMORPHIC PLANTS. CHAP. III. measurements of each form the distance between these organs in the long-sty led is to the same distan~e in the short-styled form as IOO to 69; so that the stigma in the one form does not stand on a level with the anthers in the other. The long-styled pistil is sometin1es thrice as long as that of the short-styled; but from an average of ten measurements of both, its l enD"th to that of the short-sty led was as I 00 to 56. b The stigma varies in being more or less, though slightly, lobed. The anthers also vary Inuch in length in both forms, but in a greater degree in the lon0"-sty led than in the short-sty led form ; many in the b former being from 80 to 63, and in the latter from 80 to 70 divisions of the micrometer in length. From an average of seven measurements, the shortstyled anthers were to those from the long-styled as IOO to 9I in length. Lastly, the pollen-grains from the long-styled flowers varied between I3 and II· 5 divisions of the micrometer, and those from the shortstyled between I5 and I3. rrhe average diameter of 25 grains from the latter, or short-sty led form, was to that of 20 grains from the long-sty led as I 00 to 91. We see, therefore, that the pollen-grains frOJn the smaller anthers of the shorter stamens in the longsty led form are, as usual, of smaller size than those in 'the other form. But what is remarkable, a larger proportion of the grains were small, shrivelled, ~nd worthless. This could be seen by merely com panng the contents of the anthers from several distinct plants of each form. But in one instance my son found, by counting, that out of I93 grains from a long-styled flower, 53 were bad, or 27 per cent.; whilst out of 265 grains from a short-styled flower . only I8 were bad, or 7 per cent. ~-,rom the condition of the poll.en in the long-sty led form, and from the extrmne van a- CHAP. III. PULMONARIA ANGUsrriFOLIA. 107 bility of all the organs in both forms, we may perhaps suspect that the plant is undergoing a change, and tending to become dioocious. My son collected in the Isle of Wight on two occasions 202 plants, of which 125 were long-styled and 77 short-styled; so that the former were the more numerous. On the other hand, out of 18 plants raised by me from seed, only 4 were long-styled and I4 short-styled. The short-styled plants seemed to my son to produce a greater number of flowers than the long-styled; and he came to this conclusion before a similar statement had been published by Hildebrand with respect to P. officinalis. My son gathered ten branches from ten different plants of both forms, and found the number of flowers of the two forms to be as IO? to 89, 19? b~ing sho~t-styled and I69 long-styled. With P_. offic~nahs the difference, according to Hildebrand, Is even greater, namely, as 100 flowers for the short-~ty led to 77 for the long-sty led plants. The following table shows the results of my experiments:- TABLE 20. Pulmonaria angust-ifolia. Number Number AvP.rage Nature of the Union. of of Number o Flowers Fruits Seedsi fertilised. produced. per Fruit. f Long-styled flowers, by pollen of short-} styled. Legitimate union • • • • 18 9 2•11 - Loag-s:yled Bowers, by own-form pollen'} - Illegitimate union ...... 18 0 0 Short-styled flowers, by pollen of long-} - styled. Legitimate union .... 18 15 2•60 Sh:{t-st~led flowers, by own-form pollen'} legitimate union . . . . . . 12 7 1•86 - |
