The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . es. As the phenomenon is quite common whenmore extensive sowings are made and as, especially in 372 Tricot\lous Races. perennial plants, the transition from one mode of ar-rangement to the other has been frequently observedon the same axis, as Delfino has shown, I need notenter further into it now. Sometimes it happens alsothat the main stem of a tricotylous plant bears its leavesin quaternary w-horls (Scabiosa atvopurpurea). Fasciations are a frequent consequence of tricotyly, though they som
The mutation theory; experiments and observations on the origin of species in the vegetable kingdom . es. As the phenomenon is quite common whenmore extensive sowings are made and as, especially in 372 Tricot\lous Races. perennial plants, the transition from one mode of ar-rangement to the other has been frequently observedon the same axis, as Delfino has shown, I need notenter further into it now. Sometimes it happens alsothat the main stem of a tricotylous plant bears its leavesin quaternary w-horls (Scabiosa atvopurpurea). Fasciations are a frequent consequence of tricotyly, though they sometimes do notai)pear until late in the lifeof the plant. Merciirialis an-nua and Ajuaranfus speciosusfurnished a series of instancesnearly every year during sev-eral years of culture. In theformer species they usuallyappear low on the stem; inthe latter not below the in-florescence (See Fig. 83, ). My tricotylous race ofMercurialis annua furnishedalmost all forms of 77 represents a tricotylousplant whose stem was splitfrom the first node after thecotyledons, and was therefore. Fig. yy. Mercurialis , tricotjlous seedling withsplit stem; B, a seedling thefirst whorl of leaves ofwhich was ternary; C, hemi-tricotylous plant (1900). only fasciated in the epicotvl-ous internode. Between this condition and a flat stemone centimeter broad, and much contorted, all inter-mediate stages are presented by this species. In thespring of 1887 I collected a large group of hemi-tricotyl-ous, tricotvlous and tetracotvlous seedlings fSee ) of Acer Pseudo-PIafanus not far from Hilversumand grew them for several years. Most of them I threw Tricotyly and the Arrangement of Leaves. c>7^ away as soon as they rexerted to the decussate arrange-ment of their leaves, but seven of these trees are stillalive, two with ternary stems (p. 370), two with a de-cussate arrangement of the leaves, and one with a muchflattened main stem. This last one began with threecotyledons;
Size: 1216px × 2055px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicagoopencourtpu
