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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    4. The F2 Generation from 11.35La.—This plant, 11.35La (Davis, ’12a, pp. 401-406, Figs. 10,11,12 and 13), was one of the most interesting of my hybrids because of its strong resemblance to Lamarckiana in buds and foli- age. The coloration of the stem was, however, that of Class II, i. e., it was grandiflora-like in the absence of red in the papillae on green portions of the stem. I had no means of knowing, when this plant was selected as the parent of a second generation, that its type of stem colora- tion was probably recessive to that of the red papillae as found on the biennis parent, and that I should be disap- pointed in my hope of obtaining in an F2 some plants with the stem characters of biennis D and Lamarckiana. I now believe that such a form is unable to produce in later generations plants with red papillae, and, since this is an important character of Lamarckiana, my efforts with this particular line of hybrids will be discontinued. The F2 generation from this plant, however, from the genetical standpoint proved to be one of the most interesting that I have grown and well merits a brief description. The contents of 14 capsules, containing 2,217 seeds, were sown, and after eight weeks gave a culture, 12.41, of 623 seedlings. An unusual mortality, apparently in a class of dwarfs, reduced the culture finally to 532 plants. The rosettes before they were half grown presented an ex- traordinary range of variation and it became possible to group them although this preliminary classification re- quired considerable revision later. A large group of more than 100 rosettes presented broad closely clustered and crinkled leaves of the Lamarckiana type. Many of these rosettes when half grown were indeed indistinguish- able from those of Lamarckiana at the same age. A smaller group of about 20 consisted of rosettes with narrow leaves; most of these developed into dwarf forms. Finally, the remainder, constituting what might be called the mass of the culture, contained rosettes ranging on the one hand from a number somewhat grandiflora-like to a few rosettes somewhat close to the biennis type, and be-
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