Reproduction of most lichens occurs when small pieces break off or the entire thallus (body) fragments. The fungal partner of many lichens produces spores. Lichens colonize a wide range of exposed surfaces of limbs, stumps, fence posts, soil, rocks, and other living and nonliving objects. It is the primary reference for lichen identification and related information in this fact sheet. The fungus forms the outer surface to provide support and protection, absorb moisture, and collect minerals from the air. Lichenized forms (Strigula spp.) Lichens produce their own food using sunlight energy and do not feed on the tree bark. While they grow very slowly, i.e. In vegetative reproduction, any fragment or shred of lichen containing both the algal and fungal components that breaks off the original can form a new lichen body. A diseased or stressed tree can have both lichen and separate fungal organisms growing on the same dead branch or portion of the tree. This content printed from the website located at: This website would like to use cookies to collect information to improve your browsing experience. Groerig, David J., Jim A. Chatfield, Sarah D. Ellis, Dr. Landon H. Rhodes, and Dr. Michael J. Boehm, (2009) "Lichens." The kinds that land on trees have found a stable surface that has sufficient sunlight, moisture, and minerals to sustain them. Trees and shrubs in extremely poor condition will often not respond to better care and should be replaced. Algae, lichens and moss often form green or grey, powdery or mossy, crusty growths on the stems, branches and trunks of trees and shrubs. In making these types of decisions, homeowners need to understand the unique nature of lichen and the differences between those fungi within a lichen symbiotic relationship and other fungi operating separately. A new lichen association can be created only when fungal spores come in contact with the appropriate algae or cyanobacteria in the correct habitat. The numerous species of shield lichens are one of the many glories of lichenology in the Southeast. Lichens being blamed for the decline and death of shrubs and trees is not too surprising because these unusual plantlike organisms are commonly seen on the exposed limbs and trunks of declining or dead shrubs and trees, especially azaleas, dogwoods, and pecans. Light pruning of affected limbs will remove some lichens and stimulate new shoot growth that may help shade out the remaining lichens. Most lichens on trees and shrubs are gray green; however, the color of other species varies from yellow and orange to dark brown. But the reality is, lichen is an opportunistic organism just looking for a surface to grow on, and unhealthy trees happen to be a good option. On leaves of camellia and southern magnolia, the lichen Strigula appears as numerous small gray-white crusty spots (figure 4), which later turn yellow and are shed. The bark of an older or stressed tree may become more brittle with more cracks and uneven surfaces permitting lichens to attach themselves more readily. They are diverse, adaptable, functional, and little understood. They play an important role in our natural ecosystems and can let us know when those ecosystems are in trouble. Their rhizines typically do not penetrate deep enough into the inner bark, and cause no harm to the trees they inhabit. encouraged to direct suggestions, comments, or complaints concerning any accessibility issues
Parmotrema hypotropum C Powdered ruffle lichen (a type of Shield lichen) Foliose lichen, gray-green, growing on trees (corticolous), standing up from the bark, with hair-like projections (cilia) and dusty powder (soredia) on its ruffled edges (marginal). Several species of birds and small mammals use lichens as nesting material. Lichens continue to grow during periods when dew, mist, and rain water are present but a summer dry period can cause them to become dormant until the next rainfall. The three main body groupings are crustose (crust-like,), foliose (leaf-like, seen above), and fruticose (tube or beard-like strands). Let’s look at what lichen on tree bark means and what the treatment for tree lichen is. Squamulose Lichens: The thallus is scale-like and composed of small lobes. Heavy infestations of lichens are most common on shrubs and trees in declining or poor health due to other factors. Main photo (l-r): Lichens on tree trunk; Lichen and moss on oak bark; Foliose lichen on crabapple tree branch (Photos by George H. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) is an equal opportunity educator and employer. The thallus shows no differentiation into upper and lower surfaces. The lichen bodies are attached to the outer tree bark and remain on the surface. Lichens may reproduce in a sexual, asexual, or vegetative manner. ALABAMA READY - Resources for Dealing with Hurricanes, Planting and Establishing Woody Landscape Plants, Lichens on Woody Trees and Shrubs, ANR-0857, Alabama Lichens also can be somewhat differentiated by the specific type of habitat where they live, such as rock, soil or trees, as well as their geographic distribution. In some circumstances, the fragments must break down into undifferentiated fungal and algal cells before new lichens are created. They come in dazzling shapes, colours and sizes; even working with other species to produce different organisms. Cooperative Extension System operates as the primary outreach organization Most lichen species grow best where there is sufficient light and moisture within a moderate temperature zone. Do you accept? They tend to be considered either a fortunate blessing or a frustrating pest. Many lichens are more evident on stressed or old tree trunks and branches giving the appearance of a "cause and effect" association with disease and decay. Lichens are beautiful, especially when you view a lichen-drenched Douglas-fir or a colorful crust-covered cliff, and up close when viewed under a hand-lens or microscope. When surrounded by the fungus, they provide the food to enable the lichen to exist and sustain itself in a suitable habitat. Most lichens will not thrive on heavily shaded twigs and branches of healthy woody plants. Lichens are an indication of poor plant health.