Genus

Abies

Common name

Fir

Note

A tree's characteristic shape, or habit, is in part the product of auxins, hormones which control the growth of secondary apices. The growth of an offshoot is limited by the auxin, while that of the parent branch is not. In cases of witch's broom, the normal hierarchy of buds is interrupted, and apices grow indiscriminately. This can be caused by cytokinin, a phytohormone which interferes with growth regulation. The phenomenon can also be caused by other organisms, including fungi, oomycetes, insects, mites, nematodes, phytoplasmas, and viruses. The broom growths may last for many years, typically for the life of the host plant. If twigs of witch's brooms are grafted onto normal rootstocks, freak trees result, showing that the attacking organism has changed the inherited growth pattern of the twigs. https://en.wikipedia.org/wiki/Witch%27s_broom

Certainty

90%

W
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Resolved: 2020-10-12 17:47:20