Registered volunteers can add additonal glossary terms by clicking here.

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
Titlesort descending Description
Abdomen The abdomen is this rearmost part of the three main body divisions of an insect, situated behind the head and the thorax
Aberration A genetic or environmentally produced variant on the usual form of a species, e.g. very cold conditions can produce dark forms of some species.
Abiotic A non-living chemical and physical factors in an environment, such as light, water, pressure, temperature, sound waves and rocks.
Acervulus A mat of hyphae bearing short conidiophores packed closely together.
Achene Non-splitting, one-seeded dry fruit.
Achlorophyllose Without chlorophyll.
Acicular Having the form of a needle.
Acidophile Preferring to grow in acid soils.
Acorn The nut of an oak tree that typically contains a single seed.
Actinomorphic Radially symmetrical or having more than one plane of symmetry. 
Acuminate Tapering to a long point at the apex.
Adnate (Of a gill profile) attached to stem by the full depth of the gill.
Adnexed (Of a gill profile) attached to stem by a narrower amount than the full depth of the gill.
Adpressed Closely flattened against/onto a surface
Adventitious Roots and buds that appear on a stem in abnormal places.  
Aeciospore Dikaryotic spore of a rust fungus produced in an aecium; in heteroecious rusts, a spore stage that infects the alternate host.
Aecium (pl. aecia adj. aecial) The fruiting body of a rust fungus in which the first dikaryotic spores (aeciospores) are produced.
Aedeagus The male Butterfly's mating organ.
Aerobic Any living thing that is lives or occurs only in the presence of oxygen and has a oxygen-based metablosim
Aestivation Dormancy during really hot, dry periods.
aethalium (pl. aethalia) a large, plump, pillow-shaped fruiting body of certain myxomycetes, formed by the aggregation of plasmodia into a single functional mass.
Agaric(ales) Generic term for gill-bearing fungi
Aigrette Aigrettes are the long and loose breeding feathers of birds such as herons and egrets that are typically used for courtship displays.
Air Sac A structure unique to the respiratory system of birds. Air sacs are thin-walled structures and through which air flows as the bird breathes. Air sacs enable air to flow in one direction through the...
Airfoil The airfoil around a bird's wing enables it to create lift due to the difference in airflow over the upper and lower surfaces.
Alate Having wings; winged.
Albinism A complete lack of pigmentation.
Albino Plant lacking pigmentation.
Alkaline Calcareous or chalky substrates.
Allantoid (of spores) curved as in sausage shape
Alliaceous Smelling or tasting of garlic or onions.
Allogamy Fertilisation by pollen from flowers of the same species.
Allopatric Not occurring together, as in two or more species whose territories do not overlap, resulting in geographically isolated areas that are unable to freely exchange genes.
Alternate Leaves occurring singly on opposite sides of the stem, rather than in pairs. 
Altricial Refers to mammals that are born requiring close paternal care, such as Rabbits, whereas the young of Hare (leverets) don't, they are precocial.
Alula Three feathers springing from the base of the primaries.
alveolae small hollows in a surface.
Amnion A thin membrane that encloses the embryo in an egg
Amorphous Lacking clear structure
amygdaliform (of spores) Almond shaped
Amyloid Turning blue/blue-black in iodine solution such as melzer's reagent
Anal Pertaining to the last abdominal segment, which bears the anus.
Anal Fold A portion of the hind wing that folds against the Butterfly's abdomen when at rest.
Anastomosing Fused together in a vein-like network; used to describe mushroom gills that are interconnected with veins  
Androconica Modified wing scales on Butterflies and Moths that produces pheromones. Only males have these scent scales that are used to attract females
Anemophilous Pollinated by the wind.
Annuals Annuals refers to wildflowers that grow for a single season. They usually grow quickly from seed, then often bloom for a couple of months, before dying off with the first hard frost.
Annular Ring-shaped.
Annulus Ring around stem, remnant of partial veil covering young emergent sporophore*
Antennae The sensory appendages (feelers) on the apex of the Butterfly's head that are used for sense of smell and balance.
Anterior Towards the head (front) of the Butterfly.
Anther The male organ of a flowering plant, the head of the stamen.
antheridium male sexual organ (male gametangium) found in some fungi
Anthocynanins The pigments producing purple or red colours.
Anthoxanthins The yellow pigments in plants.
Apex The top, highest part.
Aphyllous Without leaves.
Apical Apical means towards, or at, the apex (the top or uppermost point).
Apical At the tip.
Apical Towards the apex
Apiculus (of spores) a short projection at the base
Apiculus The bent tip of the antenna in Skippers.
aplanospore A non-motile spore
Apochromy Having abnormal colouration.
Apomictic Relating to a plant that reproduces by apomixis. Hawkweeds are apomictic and consist of a huge number of microspecies.
Apomixis Seed development without fertilization. Therefore a type of asexual reproduction.
Aposematic Colouration This is the bright colouring of the Butterfly's wings that protects it from predators.
apothecium (pl. apothecia) open, cuplike or saucer like, ascus-bearing fungal fruiting body (ascocarp), often supported on a stalk
Appendiculate Fringed with remains of the veil
Applanate Flattened
Aptera Primitive wingless insect group.
Apterous Without wings
Aquatic Living in, or frequenting, water
Arboreal Animals that primarily live in trees.
Arbuscules Miniscule, tree-like hyphal branching structures produced within host plant cells by arbuscular mycorrhizal fungi
Arch Arch is often used to describe a bridge of bone in the skull, such as 'zygomatic arch'
Archaeophyte An established plant believed to have been introduced by man before 1500 AD.
Arcuate (of gill profile) with concave edge in side view
Arculus In adult Odonata, an arch-shaped vein that connects the radius and median near base of the wing, forming an elongate triangle between them.
Army Army is the collective noun for group of caterpillars or ants.
Arthrospore Asexual spore formed by the septation and fragmentation of a hypha
Articulate Consisting of segments united by joints.
ascomata structures bearing or containing asci
Ascomycetes Major group containing all fungi producing spores in asci which are liberated by pressure
Ascospore Reproductive cell (spore) of the acsomycete fungi
Ascus(pl. Asci) Microscopic elongated flask-shaped cell in which ascospores are produced
Asymbiotic When symbiotic fungi are absent.
Attenuate Gradually narrowed
Auricles Structures that are ear-shaped.
Auriculars Area around the ear-opening; a circle of feathers surrounding the opening of the ear of birds
Auris The ear; an opening to the ear canal which is covered in feathers and which is located behind and slightly below the eye.
Autogamous Self-pollinating.
Aves The taxonomic class for birds. 
Axil The angle between the steb and branch or the branch and leaf.
Axillary Ventral area between the body and the wing.
Azonate Without zones or concentric markings