witches'-broom

American  

[wich-iz-broom, -broom] / ˈwɪtʃ ɪzˌbrum, -ˌbrʊm /

noun

Plant Pathology.

1. an abnormal, brushlike growth of small thin branches on woody plants, caused especially by fungi, viruses, and mistletoes.

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witches'-broom British  

/ ˈwɪtʃˌbruːm /

noun

1. a dense abnormal growth of shoots on a tree or other woody plant, usually caused by parasitic fungi of the genus Taphrina

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Etymology

Origin of witches'-broom

First recorded in 1865–70

Example Sentences

Its leaves take on odd shapes, its stems form a bushy structure called a witches’ broom and it may grow flowers that do not produce seed.

From New York Times

Plants — in this case Arabidopsis thaliana, the diminutive mustard plant that’s a common lab model — with this modification did not grow into witches’ broom shapes, and they did not live longer than uninfected plants.

From New York Times

Smeraldi argues that the Yanomami cacao’s origins in this isolated jungle could make its genetic properties attractive to the world cacao industry, which is vulnerable to climate change and blights such as the witches’ broom fungus which ravaged cacao plantations in the state of Bahia three decades ago.

From The Guardian

The first effort to seek new resistance from wild cacao plants came in the 1930s after witches’ broom made its way to the Caribbean island of Trinidad.

From Scientific American

There were signs of witches’ broom, but to the naked eye, these plants were surprisingly free of other disease.

From Scientific American