OCR Text |
Show 224 ILLEGITIMATE OFFSPRING OF CHAP. v. that the short-styled form is not rendered quite sterile by a long course of fertilisation with pollen of the same form: but as there would always be some liability to an occasional cross with the other form, we cannot tell how long self-fertilisation has been continued. PRIMULA F ARINOSA. Mr. Scott says* that it is not at all uncommon to find equalstyled plants of this heterostyled species. ~udging from t~e size of the pollen-grains, these plants owe theu structure, as m the case of P. auricula, to the abnormal elongation of the stamens of the long-styled form. In accordance with this view, they yield less seed when crossed with the long-styled form than with the short-styled. But they differ in an anomalous manner from the equal-styled plants of P. auricula in being extremely sterile with their own pollen. PRIMULA ELATIOR. It was shown in the first chapter, on the authority of Herr Breitenbach, that equal-styled flowers are occasionally found on this species whilst growing in a state of nature; and this is the only instance of such an occurrence known to me, with the exception of some wild plants of the Oxlip-a hybrid between P. veris and vulgaris-which were equal-styled. Herr Breitenbach's case is remarkable in another way; for equalstyled flowers were found in two instances on plants which bore both long-styled and short-styled flowers. In every other instance these two forms and the equal-styled variety have been produced by distinct plants. PRIMULA VULGARIS, Brit. Fl. V ar. acaulis of Linn. and P. acaulis of J acq. Var. rubra.-Mr. Scott statest that this variety, which grew in the Botanic Garden in Edinburgh, was quite sterile when fertilised with pollen fron1 the common primrose, as well as from a white variety of the same * 'Journal Proc. Linn. Soc.' viii. (1864), p. 115. t Ibid. p. 98. CHAP. V. HETEROSTYLED DIMORPHIC PLANTS. 225 species, but that some of the plants, when artificially fertilised with their own pollen, yielded a moderate supply of seed. He was so kind as to send me some of these self-fertilised seeds, from which I raised the plants immediately to be described. I may premise that the results of my experiments on the seedlings, n1ade on a large scale, do not accord with those by lVIr. Scott on the parent-plant. First, in regard to the transmission of form and colour. The parent-plant was long-styled, and of a f rich purple colour. From the self-fertilised seed 23 plants were raised; of these 18 were purple of different shades, with 2 C?f them a little streaked and freckled with yellow, thus showing a tendency to reversion; and 5 were yellow, but generally with a brighter orange centre than in the wild flower. All the plants were profuse flowerers. All were longstyled ; but the pistil varied a good deal in length even on the same plant, being rather shorter, or considerably longer, than in the normal long-styled form; and the stigmas likewise varied in shape. It is, therefore, probable that an equal-styled variety of the primrose might be found on careful search; and I have received two accounts of plants apparently in this condition. The stamens always occupied their proper position low down in the corolla ; and the ·pollengrains were of the small size proper to the long-sty led form, but were mingled with many minute and shrivelled grains. The yellow-flowered and the purpleflowered plants of this first generation were fertilised under a net with their own pollen, and the seed separately sown. From the former, 22 plants were raised, and all were yellow and long-styled. From the latter or the purple-flowered plants, 24 long-styled plants were raised, of which 17 were purple and 7 yellow. Q |