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Fasciation (pronounced / ˌ f æ ʃ i ˈ eɪ ʃ ə n /, from the Latin root meaning "band" or "stripe"), also known as cresting, is a relatively rare condition of abnormal growth in vascular plants in which the apical meristem (growing tip), which normally is concentrated around a single point and produces approximately cylindrical tissue ...
An example of the latter type is the aphid, which forms marble-sized galls on the leaf stems of cottonwood trees. While these galls have thin walls, they harbor entire colonies of aphids within. When the time is right, a slit appears on one side of the gall, allowing the aphids to escape as the slit's lips unfold.
Symptoms will often appear overnight, affecting many types of plants. Leaves and stems may turn black, and buds and flowers may be discoloured, and frosted blooms may not produce fruit. Many annual plants, or plants grown in frost free areas, can suffer from damage when the air temperature drops below 40 degrees Fahrenheit (4 degrees Celsius).
Phyllody on a purple coneflower (Echinacea purpurea). Phyllody is the abnormal development of floral parts into leafy structures. 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. [2]
The gall is a stalked, club-like smooth pouch (7−15 mm high) on the leaves of elm trees. Feeding inside the gall is a nymph and some wax. Partly formed galls are pale yellow patches with irregular lumpy projections on the top surface of the leaf. On the underside of the leaf, young galls may have a hairy opening. [6]
Edema, (also spelled oedema, and named from the analogous disorder in humans and other animals), is a disorder in plants caused by the build-up of water in plant tissues faster than the leaves can transpire. [1] [2] The excess fluid bursts the cell membranes, causing the appearance of growths, particularly on the underside of leaves. [3]
The bush coconut gall is an abnormal growth of plant tissue that occurs on the leaves, twigs or branches of the host tree. [2] Bush coconut galls have an uneven surface and variable shape but they are generally spherical and have the appearance of a small fruit.
The abnormal buds develop during the summer and the bud is wholly replaced by the growing gall. Marble galls may remain attached to the tree for several years. [7] [8] The level of attack by the insect varies greatly from year to year. [9] Oak marble galls showing two stunted and two normal-sized examples