Chimeras have been observed rarely on Long Island in a couple different plants. It is important to know that they exist because their appearance could be mistaken for being the result of a virus infection. Chimera has a genetic (not pathological) cause and thus these plants are not a concern whereas removal is often recommended for plants infected by virus so that they cannot serve as a source of virus for healthy plants nearby. Chimera is due to a mutation, typically spontaneous rather than induced, resulting in cells of different genotypes (genetic makeup) growing adjacent, which is the meaning of chimera. A common type is variegated plants, such as the one shown here. Some tissue is yellow to white because those cells are unable to synthesize chlorophyll.
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Below: images of cabbage, Brussels sprouts, and bok choy chimeras.