Glossary of terms related to cacti

Here are definitions of some of the biological terms used in this web site. I have tried to list all of the things that I feel should be defined; if you see some that are missing, then please use the Mailto or Form links, found at the end of the page, to contact me.

I have written most of these definitions as they apply to the genera Notocactus and Turbinicarpus and may not apply to plants in other Genera, e.g. the definition of an areole does not apply to members of the Genus Mammillaria where the flower does not originate on the areole.

Ø: Symbol for "diameter".
±: Symbol for "approximately".
°: Symbol for "degrees".

Acicular: Shaped like a needle.
Acute: Sharp, with an angle less than 90°.
Alveolate: Shaped like a honey comb, applied to the surface of a seed.
Anther: The part of a stamen that carries the pollen.
Anthesis: The period of time in which a flower is open.
Antrorse: Pointing upwards.
Apex: The top part of the plant, the growing point.
Appressed: Lying closely against something, usually applied to the spination of some cactus species.
Areole: The the spine bearing structure. In Notocactus and Turbinicarpus the flowers also originate here.
Aril: Fleshy, corky or hardened outgrowth of the funicle covering some seeds completely or partially, especially around the hilum.
Attenuate: Tapering gradually, usually applied to the tips of a sepal or petal.
Axil: The upper angle between a scale and the flower/fruit body. In Notocactus the bristles and hair/wool grows from here.
Axis: (With regard to the Flower.) The point from which the flower originates.
Calyx: The outermost series of leaves, commonly green, in a flower, the outer whorl of the perianth.
Campanulate: Shaped like a bell, applied to the shape of a flower.
Carpel: The female organ of flower which contains the ovules, together with the style and stigma.
Caespitose: Offsetting freely to form large clumps of plants.
Chartaceous: Paper like.
Colliculate: Covered with little rounded projections, usually applied to the surface of a seed.
Concolorous: Having the same colour throughout.
Conical: Shaped like a cone.
Connivent: Touching without becoming joined.
Corolla: A collective term for all the petals of a flower, the inner whorl of a perianth.
Cotyledon: The first developing leaves produced by a germinating seed.
Cuticle: The outer coat of the seed. See Testa.
The outer "dead" layer of the epidermis, usually wax-like.
Deflexed: Bent away, usually applied to the shape of a spine.
Dehiscent: Opening, applied when a ripe fruit opens, usually by a characteristic line or whole.
Dichotomous: Divided into two equal sized branches, usually applied to double headed plants.
Dimorphic: Having two different forms, commonly applied to the juvenile and adult forms of Turbinicarpus spines.
Distal: The "end" of something, distant from the point of attachment.
Ellipticall: Oblong shaped, with rounded ends.
Emarginate: With ends which are notched.
Embryo: A fertilised ovule.
Entire: End without indentations, usually applied to the tips of a sepal or petal.
Epidermis: The outermost layer of the "skin", usually one cell thick.
Filament: The thin thread like part of the stamen which carries the anther.
Floccose: Covered with wool or shot hairs, usually applied to an areole.
Form: The smallest degree of differentiation in plants which is formally named, i.e. only differing in single character or group of related characteristics, e.g. spine length or flower colour.
Funicle: The tread like tissue that connects the seed, via the hilum, to the fruit while it develops.
Genus: A group of related species, i.e. species with a common ancestor.
Glabrous: Lacking hairs, usually applied to an old areole or a flower scale.
Glaucous: Covered with a wax-like bloom, applied to the cuticle of some cactus species.
Globose: Roughly ball-shaped or spherical, applied to the body form of some cactus species.
Gynoecium: A collective term for all female organs of a flower, i.e. all ovaries and carpels together.
Hilum: The part of the seed where it was attached to the funicle, usually depressed and scared.
Homonym: A name that already exists for another plant. The rules set by the ICBN state that the new name must be changed.
Hypodermis: A layer of cells below the epidermis.
Hypogeous: Below the ground.
Inferior: (With regard to the ovary.) Having the ovary situated below the other flower parts. See Superior.
Lanceolate: Shaped like a lance, usually applied to the shape of a petal or sepal.
Micropyle: The opening in a ripe seed through which moisture may enter prior to germination.
Mucronate: Ending with a triangular tip.
Napiform: Shaped like a turnip, applied to the tuberous roots of some Turbinicarpus species.
Nectar: Sweet, sugar based secretion of a flower. Used to attract pollinating insects, birds, bats etc.
Nectar Chamber: The distinct area of a flower in which nectar is stored.
Nectary: A special structure within a flower where nectar is produced.
Oblanceolate: Lance shaped and attached at the wider end.
Obovate: Egg shaped and attached at the "pointy" end.
Obtuse: Blunt, with an angle greater than 90° and less than 180°, usually applied to the tips of a sepal or petal.
Ovary: The female parts of a flower, made up of the carpels.
Ovate: Egg shaped and attached at the "blunt" end.
Ovule: The embryonic seed that only develops into an embryo after fertilization by a pollen grain.
Papillate: Covered with many tiny projections, usually applied to the texture of a stigma lobe.
Parastichy: The invisible spiral line which joins the areoles on a stem.
Parietal: When the ovules arise from th outer wall of the ovary and pointing inwards.
Pectinate: Shaped like a comb, applied to the spination of various genera of cacti.
Perfect: (With regard to the Flower.) Having both male and female flower parts.
Perianth segment (Tepal): The leaf like and sterile parts of a flower, especially used if these parts are not distinguishable into calyx and corolla.
Pericarpel: The tissue around the carpels into which the gynoecium and flower is partially sunken.
Perigon: A perianth consisting of uniform elements, called tepals.
Perisperm: The nutritional tissue contained in a seed.
Petal: Coloured segment of a flower responsible for attracting pollenators. What is commonly termed petal in cactus flowers is more correctly a Perianth segment.
Pistil: The female organs of a flower consisting of the ovary, style and stigma.
Plumose: Like a feather, usually applied to the spination of Turbinicarpus seedlings and adult T. valdezianus.
Pollen: The dust like product of the anther.
Porrect: Pointing outwards.
Proximal: The "base" of something, near from the point of attachment.
Pubescent: With fine hairs.
Pulverulent: With a dusty coating.
Punctulate: Covered with very fine dots, applied to the surface of a seed.
Pungent: Having a sharp tip, usually applied to spines or Petal.
Pyriform: Shaped like a pear.
Recurved: Bent downwards or backwards.
Receptacle: The often somewhat enlarged apex of a flower stalk which carries the individual flower parts.
Regular: (With regard to the flower.) Symmetrical.
Retrorse: Pointing downwards.
Rhombic: Shaped like a diamond.
Rotate: Flattened and spread out like a clock face.
Scale: A specially developed leaf, that covers the flower bud.
Section: Taxonomic division between subgenus and genus. A group of species within a genus which have a relatively close relationship.
Seismeonasty: The movement of the stamens towards the pistil when touched.
Sepal: An individual element of the calyx.
Series: Taxonomic division between section and species. A group of species within a genus with a very close relationship.
Serrate: With edges like a saw blade.
Sessile: (With regard to the Flower.) Lacking a flower stalk.
Species: The basic unit of biological classification. This definition is open to very wide interpretation and what one person regards as just another species, may be seen by someone else, to be a totally separate genus or only a form.
Stamen: The male organ of a flower consisting of a filament and an anther.
Stigma: The uppermost part of the pistil. In Notocactus the stigma lobes are usually red, but may be yellow in some forms. In Turbinicarpus they are usually white or pink.
Stomata: The organ through which a cactus "breathes", in cacti they are found on the body and any existing leaves.
Strophiole: Corky appendage covering all or part of the hilum. Derived from the Funicle.
Sulcus: Furrow or groove.
Style: The part of the pistil that connects the carpel to the stigma.
Subgenus: The first taxonomic division below a genus.
Superior: (With regard to the ovary.) Having the ovary situated above the other flower parts. See Inferior.
Taxon: A taxonomic rank of any form, e.g. genus, subgenus, species etc.
Tepal (Perianth segment): The leaf like and sterile parts of a flower, especially used if these parts are not distinguishable into calyx and corolla.
Testa: The outer protective coat of a seed.
Tortuous: Twisted.
Transverse: Crosswise.
Truncate: Dome shape with a flattened off top, similar to the shape of a finger tip pressed on to a flat surface.
Tubercle: Generally conical outgrowth from a cactus stem, seed etc.
Tuberculate: Covered with tubercles.
Turbinate: Shaped like a top, commonly applied to the shape of a ripe Turbinicarpus fruit.
Type Species: The species selected as a type for a taxon.
Variety: The taxonomic rank between subspecies and form.
Verrucose: Covered with small warts, usually applied to the surface of a seed.
Villous: With long hairs.

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