{{Short description|Lack of hair or fur}} {{For|glabrousness in humans|Hair#Human hairlessness|Hair removal}}
'''Glabrousness''' ({{etymology|la|{{wikt-lang|la|glaber}}|bald, hairless, shaved, smooth, etc.}}) is the technical term for a lack of hair, down, setae, trichomes, or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, such as alopecia universalis in humans, which causes hair to fall out or not regrow.
==In botany== [[File:Herniariaglabra2.jpg|thumb|Smooth rupturewort (''Herniaria glabra'') - a creeping plant with glabrous leaves and stems]]
Glabrousness or otherwise, of leaves, stems, and fruit is a feature commonly mentioned in plant keys; in botany and mycology, a ''glabrous'' morphological feature is one that is smooth and may be glossy. It has no bristles or hair-like structures such as trichomes. In anything like the zoological sense, no plants or fungi have hair or wool, although some structures may resemble such materials{{which?|date=July 2025}}.
The term "glabrous" strictly applies only to features that lack trichomes at all times. When an organ bears trichomes at first, but loses them with age, the term used is '''''glabrescent'''''.
In the model plant ''Arabidopsis thaliana'', trichome formation is initiated by the GLABROUS1 protein. Knockouts of the corresponding gene lead to glabrous plants. This phenotype has already been used in gene editing experiments and might be of interest as a visual marker for plant research to improve gene editing methods such as CRISPR/Cas9.<ref>{{Cite journal|last1=Hahn|first1=Florian|last2=Mantegazza|first2=Otho|last3=Greiner|first3=André|last4=Hegemann|first4=Peter|last5=Eisenhut|first5=Marion|last6=Weber|first6=Andreas P. M.|date=2017|title=An Efficient Visual Screen for CRISPR/Cas9 Activity in Arabidopsis thaliana|journal=Frontiers in Plant Science|language=English|volume=8|page=39 |doi=10.3389/fpls.2017.00039|issn=1664-462X|pmc=5258748|pmid=28174584|doi-access=free |bibcode=2017FrPS...08...39H }}</ref><ref>{{cite journal|last1=Hahn|first1=Florian|last2=Eisenhut|first2=Marion|last3=Mantegazza|first3=Otho|last4=Weber|first4=Andreas P. M.|title=Homology-Directed Repair of a Defective Glabrous Gene in Arabidopsis With Cas9-Based Gene Targeting|journal=Frontiers in Plant Science|date=5 April 2018|volume=9|article-number=424 |doi=10.3389/fpls.2018.00424|pmid=29675030 |pmc=5895730 |doi-access=free |bibcode=2018FrPS....9..424H }}</ref> [[File:Oldenburgia grandis Emerging felted bud IMG 5837.JPG|thumb|{{center|Leaves emerging from buds of ''Oldenburgia grandis'' are densely tomentose with a dense indumentum, but their upper surface is ''glabrescent''; as seen here they lose their white felt as they mature.}}]]
==In zoology{{anchor|Glabrous skin}}== [[File:Nacktmull.jpg|thumb|Naked mole-rat (''Heterocephalus glaber'') in a zoo.]] In varying degrees most mammals have some skin areas without natural hair. In humans, glabrous skin is found on the ventral portion of the fingers, palms, soles of feet and lips, which are all parts of the body most closely associated with interacting with the world around us,<ref name ="Scholarpedia">{{cite book|editor1-last=Prescott|editor1-first=Tony J.|editor2-last=Ahissar|editor2-first=Ehud|editor3-last=Izhikevich|editor3-first=Eugene|title=Scholarpedia of Touch|date=2016|publisher=Atlantis Press|location=San Diego, USA|isbn=978-94-6239-133-8|page=9|url=https://books.google.com/books?id=SHf_CgAAQBAJ&pg=PA9|accessdate=21 February 2017}}</ref> as are the labia minora and glans penis.<ref>{{cite book|last1=Linden|first1=David, J.|title=Touch: The Science of Hand, Heart and Mind|date=March 2015|publisher=Viking|isbn=978-0241184035|chapter-url=https://books.google.com/books?id=XjZIBQAAQBAJ&pg=PT36|chapter=Chapter 2}}</ref> There are four main types of mechanoreceptors in the glabrous skin of humans: Pacinian corpuscles, Meissner's corpuscles, Merkel's discs, and Ruffini corpuscles.
The naked mole-rat (''Heterocephalus glaber'') has evolved skin lacking in general, pelagic hair covering, yet has retained long, very sparsely scattered tactile hairs over its body.<ref name ="Scholarpedia"/> Glabrousness is a trait that may be associated with neoteny.{{citation needed|date=February 2017}}
Within entomology, the term glabrous is used to refer to those parts of an insect's body which are lacking in setae (bristles) or scales.<ref name="insects">{{cite web|title=Insect Glossary|url=http://ibis.geog.ubc.ca/biodiversity/efauna/InsectGlossary.html|website=E-Fauna BC|accessdate=21 February 2017}}</ref>
==See also== * Glossary of botanical terms * Glossary of entomology terms * Trichophilia (hair fetishism) * Merkin, a "pubic wig"
==References== {{Reflist}}
Category:Plant morphology Category:Dermatologic terminology