Witches' brooms-sources of new and interesting dwarf forms of Picea, Pinus and Tsuga species

Waxman, S.

The various causes of witches' brooms in conifers are discussed. The non-pathogenic type appears to result from a bud mutation or sport and the dwarf, dense growth habit can be perpetuated vegetatively. Data are tabulated on the segregation of normal and dwarf seedlings and variability among seedlings raised from witches' brooms of Picea abies, Pinus resinosa, Pinus strobus and Tsuga canadensis. Many ornamental dwarf, semi-dwarf, weeping and variegated forms have been obtained.