Genetical studies on aenothera / Bradley moore Davis.

  • Davis, Bradley Moore.
Date:
1913
Catalogue details

Licence: In copyright

Credit: Genetical studies on aenothera / Bradley moore Davis. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    papillae). I lay no stress on the fact that in my small cultures the numbers were 86R: 80r, but merely wish to note the point that in this F2 generation two classes ap- peared sharply distinguished by the presence or absence of the character under discussion. I was unable to differentiate in this F2 other characters on the plants 11.35m and 11.35a associated with the pres- ence or absence of the red papilke (see Davis, ’12a, p. 395). There was a wide variation in habit, leaf, form, inflorescence, flower proportions and flower size (petals 2.2-3.9 cm. long), a variation that seemed unrelated to the presence or absence of red papillae. In this culture also appeared a group of 15 dwarfs, recognizable when young rosettes, which at maturity were from 5-6 dm. high, sparsely branched, and with a foliage of narrow leaves; 6 of these dwarfs had the stem coloration of the biennis parent (red papillae) and 9 that of grandiflora. Among the plants with red papillae on the stems I selected an individual, 12.43#, which among my hybrids with the stem coloration of Lamarckiana most resembled that form. I shall make this plant the starting point of a pure line with the hope that in later generations I may find variants still closer to the Lamarckiana type which may be isolated by selection. Whether the plant is homo- zygous with respect to the red coloration of the papillate glands is a point to be determined by the next generation. 2. The F2 Generation from 11.35a.—From this plant with the stem coloration of the grandiflora parent (pa- pillae green over green portions of the stem), the contents of one capsule, 432 seeds, were sown. The culture, 12.42, produced 165 seedlings of which 147 plants were brought to maturity. These presented uniformly the stem colora- ion of the Fx hybrid plant 11.35a and of the grandiflora parent. It seems then safe to conclude that such a plant as 11.35a is homozygous as to its stem coloration with possibly the formula of a recessive (rr) lacking the factor that produces the red color in the papillate glands. This position is supported by the evidence from the much