Trichomes (); ) are fine outgrowths or appendages on

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

s, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant is an

indumentum In biology, an indumentum (Latin, literally: "garment") is a covering of trichomes (fine "hairs") on a plant Davis, Peter Hadland and Heywood, Vernon Hilton (1963) ''Principles of angiosperm taxonomy'' Van Nostrandpage, Princeton, New Jersey, pa ...

, and the surface bearing them is said to be pubescent.

Algal trichomes

Certain, usually filamentous, algae have the terminal

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

produced into an elongate hair-like structure called a trichome. The same term is applied to such structures in some cyanobacteria, such as '' Spirulina'' and ''

Oscillatoria ''Oscillatoria'' is a genus of filamentous cyanobacterium which is often found in freshwater environments, such as hot springs, and appears blue-green. Its name refers to the oscillating motion of its filaments as they slide against each other ...

''. The trichomes of cyanobacteria may be unsheathed, as in ''Oscillatoria'', or sheathed, as in ''

Calothrix ''Calothrix'' is a genus of cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms ...

''. These structures play an important role in preventing soil

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is dis ...

, particularly in cold desert

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologi ...

s. The filamentous sheaths form a persistent sticky network that helps maintain soil structure.

Plant trichomes

Plant trichomes have many different features that vary between both species of plants and organs of an individual plant. These features affect the subcategories that trichomes are placed into. Some defining features include the following: * Unicellular or multicellular * Straight (upright with little to no branching), spiral (corkscrew-shaped) or hooked (curved apex) * Presence of cytoplasm * Glandular (secretory) vs. eglandular * Tortuous, simple (unbranched and unicellular), peltate (scale-like), stellate (star-shaped) *

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