page_title: Phyllody
section_title: Description
hierarchical_section_title: Phyllody / Description
caption_attribution_description: English: Flower of Petunia, opened to show the stamens partially replaced by stalked leaves
context_page_description: Phyllody is the abnormal development of floral parts into leafy structures. It is generally caused by phytoplasma or virus infections, though it may also be because of environmental factors that result in an imbalance in plant hormones. Phyllody causes the affected plant to become partially or entirely sterile, as it is unable to normally produce flowers.
  The condition is also known as phyllomorphy or frondescence; though the latter may sometimes refer more generically to foliage, leafiness, or the process of leaf growth. Phyllody is usually differentiated from floral virescence, wherein the flowers merely turn green in color but otherwise retain their normal structure. However, floral virescence and phyllody, commonly occur together as symptoms of the same diseases. The term chloranthy is also often used for phyllody, though in some cases it may refer to floral virescence.
context_section_description: Phyllody is characterized by the partial or complete replacement of floral organs with true leaves. Phyllody can affect bracts, the calyx (sepals), corolla (petals), the gynoecium (carpels/pistils), and the androecium (stamens). Phyllody may be partial, affecting only some sets of floral organs or even only half of a set of floral organs (e.g. only three petals out of six in a single flower); or it can be complete, with all the floral organs replaced by leaves.
  Phyllody of the bracts is common among plants which bear catkin (amentaceous) inflorescences. They are very common among members of the genus Plantago, for example, as well as the common hop (Humulus lupulus). Involucral bracts of the flowers of members of the family Asteraceae like dahlias and dandelions, may also be affected.
  Sepals that exhibit phyllody are usually hard to detect due to fact that most sepals already resemble leaves. Close examination, however, can reveal differences in venation in normal sepals and sepals that exhibit phyllody. The full development of perfect leaves from sepals is more common among flowers that have united sepals (monosepalous) than in flowers with separated sepals (polysepalous).
  Phyllody of the petals can be expressed more mildly as a simple change in shape and color (in which case, it's more accurately virescence), or it can be expressed as fully formed leaves. It is more common among flowers which exhibit corollas of distinct petals (polypetalous) than in flowers in which the petals are fused into a single tube or bowl-like structure (monopetalous).
  Phyllody of the stamens is rare. In fact, the stamens are the least likely of the floral organs to be affected by phyllody. This is thought to be because the stamens are the most highly differentiated organs in flowers.
  In contrast, phyllody of the carpels is much more common than the corresponding changes in stamens. Usually, phyllody affects the proximal parts of the carpel (the ovary) more than the distal parts (the style and stigma). The ovule itself may be exposed on the edges or on the inner surface of the carpel if the ovary becomes leaf-like. If the ovule is affected by phyllody, it develops separately from the rest of the carpel. The best known example of phyllody of the carpels is found in the Japanese cherry (Prunus serrulata), in which one or both of the carpels can become leaf-like (although the distal half of the style and the stigma are usually unaffected). Incidentally, some Japanese cherry cultivars also exhibit "doubling" of the petals due to petalody, where a second corolla develops instead of stamens.
caption: Illustration from Vegetable Teratology (1869), showing a Petunia flower with stamens partially replaced by "stalked" leaves. The stalks are actually the retained filaments of the stamens, while the anthers have been replaced by small leaves.
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