noun
1Botany
The tendency of a plant part, especially a root or shoot, to grow in a straight line or to retain its normal spatial orientation even in the presence of altered tropic stimuli (such as light or gravity).2Mycology
The tendency of a fungal hypha to grow towards or away from another hypha in the same mycelium, or of the germ-tube of a germinating spore to grow towards or away from a spore of the same species.
Origin
Late 19th century; earliest use found in The Botanical Gazette. From auto- + -tropism.
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