ISHS Acta Horticulturae 54: Symposium on Propagation in Arboriculture
WITCHES'-BROOMS' SOURCES OF NEW AND INTERESTING DWARF FORMS OF PICEA, PINUS AND TSUGA SPECIES |
| Author: | S. Waxman |
| DOI: | 10.17660/ActaHortic.1975.54.3 |
| Abstract:
A potential source of new forms of evergreens is the witches'-broom: a dense abnormal growth that arises from mutated buds on coniferous trees. As opposed to pathogen caused brooms, these generally retain their dwarf and dense character when propagated vegetatively. The grafting of witches'-broom tissue has been done since 1874 and is the origin of such dwarf evergreens as Pinus sylvestris Beauvronensis' and Pinus nigra 'Hornibrookiana'. The number of different forms from which selections can be made is limited by the number of witches'-brooms found. A much larger number of different plant forms is possible, however, from the seed of the broom. Several thousand seedlings of Pinus strobus, P. sylvestris, P. rigida, P. resinosa, Piceaabies, and Tsuga canadensis have been grown at the University of Connecticut and have produced many interesting forms that are dwarf, semi-dwarf, weeping and variegated. Propagation of the witches'-broom seedlings by cuttings has been accomplished, but appears to be limited to plants no older than approximately 5 years. | |
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