Certain flaws are necessary for the whole. It would seem strange if old friends lacked certain quirks.” — Goethe
Imagine you caught a virus that caused fingers to grow from your genitals. That, in the broadest sense, is phyllody
“Johann Wolfgang Von Goethe, the German poet best known for his work Faust, was also an astute botanical observer. In 1790, he described the strange appearance of rose flowers in which flower organs were replaced by leaf- and stem-like structures. …In 1869, Maxwell T. Masters named the condition “phyllody” (fil-o-dee) in his book devoted to plant abnormalities.” – Phyllody in Roses, Sim, Rowhani and Golino; UC Davis, pdf
Leaf-like structures growing where parts of flowers should be? What’s the cause?
Phyllody is a result of hormonal imbalance, commonly caused by environmental conditions such as heat stress and drought, and by severe insect damage.
Heat and drought being in plentiful supply these last three years in Kansas–already a paradise for enraged insects–it was only mildly surprising to discover a phyllodic mutation on an Echinacea purpurea plant in last year’s garden. As phyllody is an untreatable disease transmitted by phloem-munching bugs, leafhoppers in particular, the only remedy was to pull the affected plant and dispose of it in the covered garbage bin–not on the insect-accessible compost heap. Better yet, burn it.
The pathogens that cause phyllodic mutations are called phytoplasmas, parasitic bacteria that feed on the vascular tissue of plants. Remembering our grade school biology lessons, the phloem is the vascular tissue that conducts sugars and other metabolic products downward from the leaves. Phytoplasmas live and replicate in the phloem. The sugars in the phloem attract sap-sucking insects, the phytoplasmas hitch a ride. Insecticides are often used to control insect vectors but they also kill off many beneficial insects and pollinators. The most common treatment is the destruction of affected plants, which often carries significant economic consequences.
“Aster yellows is a disease you see almost everywhere. It causes conspicuous symptoms and affects many different kinds of plants. It occurs on buckwheat, red clover, tomato, carrot, lettuce, onion, parsnip, salsify, and spinach; on such common weeds as daisy fleabane, dandelion, horseweed, plantain, ragweed, and wild lettuce in grasslands, forests, and waste places; and on such popular flowers as calendula, Centaurea, China aster, chrysanthemum, Clarkia, cockscomb, coreopsis, cosmos, gaillardia, marigold, nemesia, petunia, phlox, Scabiosa, snapdragon, Statice, straw-flower, and Veronica in gardens even penthouse gardens throughout the country.” – L. O. Kunkel, Plant Diseases.
In rare instances, phyllodic mutation is desirable: the Green Rose, Rosa chinensis var. viridiflora, “…an ancient Chinese rose cultivar which exhibits green leafy bracts in tight flower-like clusters. In green rose, artificial selection has enabled phyllody to be expressed as a stable mutation.” – Wikipedia