Phyllody

It is generally caused by phytoplasma or virus infections,[1] though it may also be because of environmental factors that result in an imbalance in plant hormones.

[5] However, floral virescence and phyllody (along with witch's broom and other growth abnormalities), commonly occur together as symptoms of the same diseases.

The concepts he discusses while describing metamorphosis is now known as homology, the basis of the modern science of comparative anatomy and a discovery that is usually credited to the English biologist Sir Richard Owen.

[5] Nineteen years later, the Belgian botanist Charles Jacques Édouard Morren also investigated the phenomenon in his book Lobelia (1851).

Morren called the condition "phyllomorphy", and unlike Engelmann, Morren explicitly distinguished phyllomorphy (wherein the floral parts are replaced by leaf-like structures) from virescence (wherein the affected parts, not necessarily floral, turn green but retain the original form or structure).

[5] The term "phyllody" was coined by the English botanist Maxwell T. Masters in his book on plant abnormalities, Vegetable Teratology (1869).

Incidentally, some Japanese cherry cultivars also exhibit "doubling" of the petals due to petalody, where a second corolla develops instead of stamens.

[19] The most common of these insect vectors are leafhoppers,[19] an example of which is Hishimonus phycitis, which transmits the phytoplasma-caused little leaf phyllody in eggplants.

[23][24] Environmental abiotic factors like hot weather or water stress that result in an imbalance in plant hormones during flowering can cause phyllody.

[2] Phyllody can be artificially induced by applying cytokinins (CK), plant hormones responsible for cell division, as well as apical dominance and axillary bud growth.

Conversely, it can be subsequently suppressed with the application of gibberellins (GA), plant hormones responsible for stem elongation, flowering, and sex expression.