Growths on trees often prompt questions of their edibility. What many refer to as “tree moss” might not be moss at all, but rather lichens, leading to significant confusion. While true mosses and lichens share habitats and some superficial similarities, their biological classifications and, importantly, their edibility, differ considerably. Navigating this distinction is important for anyone considering foraging, as misidentification can have health implications.
Understanding Tree Moss Edibility
True tree moss is generally not considered edible or nutritious for humans. Mosses are non-vascular plants, meaning they lack specialized tissues for efficient water and nutrient transport. They primarily absorb water and nutrients directly through their simple, leaf-like structures. While not overtly poisonous, consuming true moss can lead to digestive upset due to its fibrous texture and lack of substantial nutritional value. Humans are not well-equipped to digest the tough plant matter of mosses efficiently, and eating large quantities may cause stomach problems.
A frequent source of confusion arises because many people mistakenly refer to lichens as “tree moss.” Lichens are complex organisms resulting from a symbiotic relationship, typically between a fungus and an alga or cyanobacterium. Unlike mosses, which are true plants, lichens are not plants. Some types of lichens are indeed edible and have been historically consumed by various cultures, sometimes serving as a famine food or even a delicacy in certain regions. However, the edibility of lichens is not universal, and proper identification remains paramount.
How to Distinguish Moss from Lichens
Differentiating between true moss and lichens is important for safe foraging, as they possess distinct physical characteristics. Mosses are small, flowerless plants that typically grow in dense, soft mats or clumps. They are usually green, though some species can appear yellow, brown, or even purple. Mosses have simple leaf-like structures and are anchored to surfaces by thread-like rhizoids, which are not true roots. These plants absorb moisture and nutrients directly through their leaves, which is why they thrive in damp, shady environments.
Lichens, in contrast, exhibit a wider range of forms and colors and are not true plants. They are categorized into several main growth forms. Crustose lichens appear as thin, flat crusts that adhere tightly to surfaces. Foliose lichens have a leafy or lobed appearance and are attached to the substrate at one or more points. Fruticose lichens are typically shrubby, bushy, or hair-like and attach at only a single point at their base. Their colors can vary widely, including shades of green, grey, yellow, orange, red, and brown.
Safety Precautions and Consumption Guidelines
Consuming true moss is generally not recommended due to its fibrous nature and minimal nutritional value, which can lead to digestive discomfort. While some sources suggest moss can be eaten in survival situations, it offers very little in terms of calories, vitamins, or minerals. Even if a moss species is not toxic, its rough texture can be difficult to process, and it may contain bacteria or parasites if not properly cleaned and cooked.
For lichens, extreme caution is necessary. While some lichens are known to be edible, many are inedible or contain mildly toxic compounds that require specific preparation methods to remove. Lichens can absorb pollutants from their environment, including heavy metals and pesticides. This absorption capability makes them useful as bioindicators of air quality, but it also means consuming them from contaminated areas can transfer these substances to the consumer.
Therefore, positive identification by an expert is absolutely necessary before considering any lichen for consumption. If an edible lichen is identified, preparation typically involves thorough washing and boiling to remove bitterness and potentially harmful compounds.