Trichomes, from the Greek meaning "growth of hair", are fine outgrowths or appendages on plants and certain protists. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly Hair is a keratinised protein filament that grows through the epidermis from follicles deep within the Dermis. Plants are living Organisms belonging to the kingdom Plantae. Protists (ˈproʊtɨst are a diverse group of eukaryotic Microorganisms Historically protists were treated as the kingdom Protista but this These are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae.
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Algal trichomes
Certain—usually filamentous—algae, have the terminal cell produced into an elongate "hair-like" structure called a trichome. Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called The same term is applied to such structures in some cyanobacteria. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy
Plant trichomes
Aerial surface hairs
Trichomes on plants are epidermal outgrowths of various kinds. The terms emergences or prickles refer to outgrowths that involve more than the epidermis. Spines are leaves that have been modified into cylindrical hard structures with sharp ends This distinction is not always easily applied (see Wait-a-bit climber). Also, there are nontrichomatous epidermal cells that protrude from the surface.
A common type of trichome is a hair. Plant hairs may be unicellular or multicellular, branched or unbranched. Multicellular hairs may have one or several layers of cells. Branched hairs can be dendritic (tree-like), tufted, or stellate (star-shaped). ,
A common type of trichome is the scale or peltate hair: a plate or shield-shaped cluster of cells attached directly to the surface or borne on a stalk of some kind.
Any of the various types of hairs may be glandular.
In describing the surface appearance of plant organs, such as stems and leaves, many terms are used in reference to the presence, form, and appearance of trichomes. A stem is one of two main structural axes of a Vascular plant. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. The most basic terms used are glabrous—lacking hairs— and pubescent—having hairs. Details are provided by:
- glabrous, glabrate – lacking hairs or trichomes; surface smooth.
- hirsute – coarsely hairy
- hispid – having bristly hairs
- downy – having an almost wool-like covering of long hairs
- pilose – pubescent with long, straight, soft, spreading or erect hairs
- puberulent – minutely pubescent; having fine, short, usually curly, hairs
- pubescent – bearing hairs or trichomes of any type
- strigillose – minutely strigose
- strigose – having straight hairs all pointing in more or less the same direction as along a margin or midrib.
- villosulous – minutely villous
- villous – having long, soft hairs, often curved, but not matted
Hairs on plants are extremely variable in their presence across species, location on plant organs, density (even within a species), and therefore functionality. However, several basic functions or advantages of having surface hairs can be listed. It is likely that in many cases, hairs interfere with the feeding of at least some small herbivores and, depending upon stiffness and irritability to the "palate", large herbivores as well. Hairs on plants growing in areas subject to frost keep the frost away from the living surface cells. In windy locations, hairs break-up the flow of air across the plant surface, reducing evaporation. Dense coatings of hairs reflect solar radiation, protecting the more delicate tissues underneath in hot, dry, open habitats. And in locations where much of the available moisture comes from cloud drip, hairs appear to enhance this process.
Root hairs
Root hairs, the rhizoids of many vascular plants, are tubular outgrowths of trichoblasts, the hair-forming cells on the epidermis of a plant root. Rhizoids are a structure in plants and fungi that functions like a root in support or absorption Vascular plants (also known as tracheophytes or higher plants) are those Plants that have lignified tissues for conducting ROOT is an object-oriented program and library developed by CERN. That is, root hairs are lateral extensions of a single cell and only rarely branched. Just prior to the root hair development, there is a point of elevated phosphorylase activity. Phosphorylase is a family of allosteric Enzymes that catalyze the production of Glucose-1-phosphate from a polyglucose such as Glycogen
Root hairs vary between 5 and 17 micrometres in diameter, and 80 to 1,500 micrometres in length (Dittmar, cited in Esau, 1965).
Root hairs can survive for 2 to 3 weeks and then die off. At the same time new root hairs are continually being formed at the top of the root. This way, the root hair coverage stays the same.
It is therefore understandable that repotting must be done with care, because the root hairs are being pulled off for the most part. This is why planting out may cause plants to wilt.
See also
References
- Esau, K. Seta (plural setae) is a biological term derived from the Latin word for " Bristle " For the city see Kief North Dakota. Not to be confused with "Kieff" an obsolete translation of " Kiev " 1965. Plant Anatomy, 2nd Edition. John Wiley & Sons. 767 pp.
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