Glossary of Taxonomic Terms
Commonly Employed in the Identification of Woody Plant
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
A
Achene – A small, dry, one-seeded, indehiscent fruit (one that doesn’t split open), e.g. fruit of members of the Asteraceae.
Acuminate – The shape of a tip (apex) or base of a leaf or perianth segment where the part tapers gradually and often in a concave manner.
Acute – Evenly narrowed into a point at an angle of less than 90 degrees.
Adnate – Grown together or fused, used only to describe unlike parts. For comparison, connate.
Adventitious – Arising from an unusual or irregular position, such as roots along a stem.
Aggregate flower – Heaped or crowded into a dense cluster.
Aggregate fruit – One formed by the fusion of pistils that were distinct in a single flower (e.g. Rubus, raspberry, blackberry).
Alternate – Arrangement of leaves or parts one at a node, as leaves on a stem. For comparison, opposite or whorled.
Ament – A catkin, or scaly spike.
Angiosperm – Having seeds borne within a pericarp. For comparison, gymnosperm.
Anther – Pollen-bearing part of a stamen, borne at the top of a filament.
Apetalous – Without petals, e.g. flowers of grasses.
Apex – The tip or terminal end.
Apical – Describes the apex or tip.
Apiculate – Ending abruptly in a short pointed tip which is not stiff.
Appressed – Pressed close to or lying flat against, as leaves on a stem or hairs on a leaf.
Auriculate – Having ear-like appendages, as the projections of some leaf and petal bases.
Axil – The angle between a stem and an attached leaf.
Axis – The main stem.
Axillary – Borne or carried in the axil.
B
Berry – A fleshy, indehiscent, pulpy, multi-seeded fruit resulting from a single pistil, e.g. tomato.
Bipinnate – Twice pinnate, the primary leaflets being again divided into secondary leaflets.
Bloom – A waxy coating sometimes found on a stem, leaf, flower or fruit surface, usually of a grayish cast and easily removed.
Boss – A raised, usually rounded protuberance.
Bract – A much-reduced leaf, often scale-like and usually associated with a flower or inflorescence
Broad-elliptic – Wider than elliptic.
Broad-ovate – Wider than ovate.
Bud scale – A modified leaf or stipule (there may be one, a few, or many) protecting the tissue of the bud.
Bud scale scar – The mark left by the sloughing off of the bud scale.
Bullate – Having a puckered or blistered appearance.
Bundle scar – Seen in the leaf scar, the broken end of the woody vascular strands that connected the leaf to the stem.
C
Caducous – Falling off very early as compared to similar structures in other plants.
Calyx – The outer whorl of perianth, composed of the sepals, usually green in color and smaller than the inner set.
Capsule – A dry dehiscent fruit produced from a compound pistil, e.g. fruit of a tobacco, Catalpa, Dianthus.
Catkin – A spike-like inflorescence, comprised of scaly bracts subtending unisexual flowers, often somewhat flexuous and pendulous, e.g. inflorescence of Salix, willow and Populus, poplar.
Chambered – Pith divided into hollow, horizontally arranged, separated by cross partitions.
Cilia – Marginal hairs.
Ciliate – Marginally fringed with hairs, often minutely so, and then termed “ciliolate.”
Clone – A group of plants, usually derived vegetatively, from one parent plant, identical to each other and to the parent.
Coarse texture – Consisting of large or rough parts.
Compound leaf – A leaf of two or more leaflets.
Cone – A coniferous reproductive structure, having a number of woody, leathery, or fleshy scales, each bearing one or more seeds, and attached to a central axis.
Conical – Cone-shaped, as the young form of many spruces.
Coniferous – Cone bearing.
Connate – Describing similar structures united or fused together.
Cordate – Heart-shaped, with a sinus and rounded lobes.
Corolla – Inner whorl of the perianth, between the calyx and the stamens; a collective term for the petals of a flower.
Corymb – A more or less flat–topped indeterminate inflorescence whose outer flowers open first, e.g. Viburnum, some verbenas.
Cotyledon – The primary leaves of the embryo, present in the seed. One of the first leaves to appear after germination (there may be more than 1).
Crenate – Rounded teeth on margin, e.g. leaves of some coleus.
Crenulate – Having very small, rounded teeth.
Cultivar – A form of a plant derived from cultivation. Cultivar names are indicated by single quotation marks.
Cuneate – Wedge-shaped with essentially straight sides, the acute angle at the base and the structure attached at the narrow end.
Cyme – A more or less flat-topped determinate inflorescence whose outer flowers open last, e.g. Sambucus, elderberry.
D
Dehiscent – Splitting open. The term is commonly applied to anthers or seed pods.
Decompound – Having more than one compound.
Dentate – Having sharp, marginal teeth whose apices are perpendicular to the margin.
Determinate – Describes an inflorescence in which the terminal flower blooms first, thereby halting further elongation of the flowering stem. For comparison, indeterminate.
Dicot – Angiosperm plant having two cotyledons.
Dimorphic – Having two forms.
Dioecious – Having unisexual flowers, each sex confined to a separate plant, said of species.
Double serrate – Serrations bearing minute teeth on margins.
Drupe – A fleshy, indehiscent fruit whose seed is enclosed in a stony endocarp, e.g. date, cherry.
E
Ellipsoid – Three-dimensional shape of ellipse, football shaped.
Elliptic-oblong – A shape between the two forms.
Elliptical – Having the outline of an ellipse, broadest at middle and narrower at each end.
Emarginate – With a shallow notch at the apex.
Endocarp – The inner layer of the pericarp. For comparison, exocarp, mesocarp.
Entire – Having a margin without teeth or lobes.
Even-pinnate – Results in a lack of the terminal leaflet, since each one is paired.
Exocarp – Outer layer of the pericarp of a fruit. For comparison, endocarp, mesocarp.
Exfoliate – To peel off in shreds or thin layers, as bark from a tree.
F
Falcate – Sickle-shaped.
Fascicle – A close cluster or bundle, e.g. leaves of white pine.
Filiform – Long and very slender; thread-like.
Fine texture – Consisting of small, rather delicate parts.
Flaking – Shreddy, with shorter fragments.
Follicle – A dry dehiscent fruit opening only along one suture and the product of a single carpel (simple ovary), e.g. Paeonia, peony, Aquilegia, columbine, Asclepia, milkweed.
Fruit – Technically a ripened ovary with its adnate parts, the seed-containing unit characteristic of all Angiosperms.
G
Genus – A group of species possessing fundamental traits in common but differing in other lesser characteristics; a taxonomic grouping of similar species (pl. genera); similar genera are grouped into families.
Glabrous – Not hairy. Note: a glabrous surface need not be smooth, for it may be bullate or rugose.
Glandular – Bearing glands.
Glaucescent – Slightly glaucous.
Glaucous – Covered with a waxy bloom or whitish material that rubs off readily, e.g. the bloom on many sorts of grape.
Globose – Having a round or spherical shape.
Grooved – Marked with long narrow furrows or channels.
Gymnosperm – Plant with the ovules borne naked or unprotected, the conifers or cone-bearing plants and their allies. For comparison, angiosperm.
H
Hairy – Pubescent with long hairs.
Hispid – With stiff or bristly hairs.
Hirsute – Pubescent with coarse or stiff hairs.
I
Imbricated – Overlapping, as shingles on a roof.
Imperfect – A flower that lacks either stamens or pistils.
Incised – Cut by sharp and irregular incisions more or less deeply, but intermediate between toothed and lobed.
Indehiscent – Not opening regularly, as a capsule or anther.
Indeterminate – Describes an inflorescence in which the outer or lower flowers bloom first, allowing an indefinite elongation of the flowering stem. For comparison, determinate.
Indumentum – With a generally heavy covering of hair; a general term without precise connotation.
Inferior – Beneath, below; said of an ovary when situated below the apparent point of attachment of stamens and perianth.
Inflorescence – The arrangement of flowers on the axis.
Involucre – One or more whorls or series of small leaves or bracts that are close underneath a flower or inflorescence.
J
Juvenile – An early phase of plant growth, usually characterized by non-flowering, vigorous increase in size, and often thorniness.
L
Lanceolate – Much longer than wide, broadest below the middle and tapering to the apex.
Lateral bud – A bud borne in the axil of a previous season’s leaf.
Latex – Milky sap.
Leaf scar – The mark remaining after the leaf falls off a twig.
Lenticel – A small corky spot on young bark made of loosely packed cells, providing gaseous exchange between the inner tissues and the atmosphere.
Linear – Long and very narrow, as in blades of grass.
Lobe – A projecting part or segment of an organ as in a lobed ovary or stigma; usually a division of a leaf, calyx, or petals cut to about the middle (i.e., midway between margin and midrib).
M
Margin – The edge of a leaf.
Marginal – Pertaining to the margin.
Mature – A later phase of growth characterized by flowering, fruiting, and a reduced rate of size increase.
Mesocarp – Middle layer of the pericarp of a fruit. For comparison, endocarp, exocarp.
Milky sap – Whitish in color, often thicker than water.
Monoecious – A species with unisexual flowers, having both male and female flowers on the same plant, e.g. corn.
Mucro – A short, sharp, abrupt tip.
Mucronate – Abruptly terminated by a mucro.
Multiple buds – A terminal or lateral bud crowded by many accessory buds.
Multiple fruit – A fruit formed when the pistils of separate flowers form a single structure with a common axis (e.g. Morus, mulberry)
N
Naked bud – One without scales.
Native – Inherent and original to an area; pre European influence in the United States..
Needle – The slender leaf of many conifers.
Nerve – A slender rib or vein, especially unbranched.
Node – A joint on a stem, represented by point of origin of a leaf or bud; sometimes represented by a swollen or constricted ring, or by a distinct leaf scar.
Nut – A dry, indehiscent, 1-celled, 1-seeded fruit having a hard and bony mesocarp; the outermost endocarp may be fibrous or slightly fleshy.
O
Obscordate – The apex being cordate.
Oblanceolate – Inversely lanceolate.
Oblique – Lop-sided, as one side of a leaf base larger, wider or more rounded than the other.
Oblong – Longer than broad; rectangular; the sides nearly parallel.
Oblong-lanceolate – a shape in between the two forms.
Oblong-obovate – A shape in between the two forms.
Obovate – Inversely ovate, broadest above the middle.
Obovoid – Three dimensional shape of obovate, pear shaped.
Obtuse – Rounded, approaching the semi-circular.
Opposite – Describing leaves that are situated in pairs at a node along an axis.
Orbiculate – Circular or disk-shaped, e.g. leaf of common nasturtium.
Oval – Twice as long as broad, widest at the middle, both ends rounded.
Ovate – Egg-shaped in outline, broadest below the middle.
Ovate-oblong – A combination of the two forms.
P
Palmate – Digitate, radiating, fan-like from a common point, as in leaflets of a palmately compound leaf or veins or palmately-veined leaf.
Panicle – An indeterminate inflorescence whose primary axis bears branches of pedicelled flowers (at least basally so); a branching raceme.
Pedicel – Stalk of a single flower in an inflorescence.
Peduncle – Stalk of a flower or inflorescence.
Peltate – Having the petiole attached inside the margin, such a leaf is typically shield-shaped.
Pendulous – More or less hanging or declined.
Perfect – Having both functional stamens and pistils (not imperfect); a unisexual flower.
Perianth – A collective term embracing both the corolla and the calyx.
Pericarp – A term used by some to designate a fruit; technically, the ovary wall.
Periderm – A protective layer of corky cells.
Petiole – Leaf-stalk of simple leaves.
Petiolule – Leaflet-stalk of compound leaves.
Pilose – Shaggy with soft hairs.
Pinna – The leaflet of a compound leaf; in ferns, the primary division attached to the main rachis; feather-like.
Pinnate – Compound, with leaflets or pinnae arranged feather-like on either side of a common axis or rachis.
Polygamous – Bearing unisexual and bisexual flowers on the same plant.
Pome – A type of fleshy, indehiscent fruit represented by the apple, pear and related genera, resulting from a compound ovary.
Prickle – An excrescence of bark that is small, weak, and spine-like.
Pseudo-terminal bud – Seemingly the terminal bud of a twig, but actually the upper-most lateral bud with its subtending leaf scar on one side and the scar of the terminal bud often visible on opposite side.
Pubescent – Covered with short soft hairs; a general term.
Pyramidal – Broadest at base, tapering apically; pyramid-shaped.
R
Raceme – A simple indeterminate inflorescence, having a single long axis, with pedicelled flowers.
Rachilla – A diminutive or secondary axis; a branch of a rachis; the minute axis bearing the individual florets in grass and sedge spikelets; the secondary axes of decompound fern fronds.
Rachis – Axis-bearing leaflets or the primary axis of an inflorescence; the axis bearing pinnae of a fern frond.
Ranked – Foliage is arranged in longitudinal planes around the stem.
Receptacle – A torus; the distal end of a flower-bearing axis, usually more or less enlarged, flattened, or cup-like on which some or all of the flower parts are borne, e.g. Asteraceae, Onagraceae.
Reflexed – Bent abruptly backward or downward.
Reniform – Kidney-shaped or rounded with a notch at the base.
Resin duct – A lengthwise or transverse canal carrying resins.
Resinous – Secreting a viscid exudate.
Reticulate – Like a net, the interstices closed.
Rhombic – With four nearly equal sides, but unequal angles, diamond shaped.
Rugose – Wrinkled, usually covered with wrinkles.
S
Samara – A dry indehiscent fruit bearing a wing (the wing may be limb-like or envelop the seed and be wafer-like), e.g. Acer, maple, Fraxinus, ash, Ptelea, hoptree.
Scar – The mark left from a former attachment.
Schizocarp – A dry dehiscent fruit that splits into two halves, e.g. Acer, maple.
Sepal – A single segment of a divided calyx.
Serrate – Saw-toothed, the teeth pointing forward.
Serrulate – Minutely serrate.
Sessile – Without a stalk.
Simple – Said of a leaf when not compound, of an inflorescence when unbranched.
Sinuate – With a strongly wavy margin.
Sinus – The space between two lobes, segments, or divisions; as of leaves or perianth parts.
Solitary – Borne singly, not paired or clustered.
Spatulate – Spoon-shaped.
Species – A natural group of plants composed of similar individuals which can produce similar offspring; usually including several minor variations.
Spike – A unbranched, elongated, simple, indeterminate inflorescence whose flowers are sessile; the flowers may be congested or remote.
Spikelet – (1) a secondary spike; (2) one part of a compound inflorescence which of itself is spicate; (3) the floral unit, or ultimate cluster, of a grass inflorescence comprised of flowers and their subtending bracts.
Spine – a sharp-pointed rigid structure, usually a highly modified stem.
Squarrose – With branches spreading and recurved at the ends.
Stalked bud – A bud whose outer scales are attached above the base of the bud axis.
Stamen – Male or pollen-bearing organ of a flower, composed of filaments and anthers.
Stellate – Star-like; with radiating branches or separate hairs aggregated in star-like clusters; often said of hairs that branched.
Stipel – A stipule of a leaflet.
Stipule – A basal appendage of a petiole, usually one at each side, often ear-like and sometimes caducous.
Striate – With fine longitudinal lines, channels or ridges.
Strigose – With sharp, stiff, straight and appressed hairs.
Strobilus – A cone.
Subtend – To occupy a position below and adjacent to.
Sympodial – Continuing growth by the development of an axillary bud and not the terminal bud, season after season.
T
Tendril – A modified stem or leaf, usually filiform, branched or simple, that twines about an object providing support.
Tepal – A segment of perianth not differentiated into calyx or corolla, e.g., tulip, magnolia.
Terminal – At the tip or distal end.
Ternate – Arranged or divided in threes.
Thorn – A modified twig which has tiny leaf scars and buds; can be single or branched.
Tomentose – Densely woolly, the hairs soft and matted.
Translucent – Transmitting light but diffuse enough to distort images.
Trifoliate – Three-leaved, e.g. Trillium.
Truncate – As if cut off at right angles to the primary axis; a term applicable to bases or apices.
U
Umbel – An indeterminate inflorescence, usually but not necessarily flat-topped with the pedicels and peduncles (termed rays) arising from a common point, resembling the stays of an umbrella.
Umbo – A conical projection arising from the surface.
Undulate – Wavy, as in a leaf margin.
Unisexual – Bearing either stamens or pistils but not both.
V
Valvate – (1) dehiscing by valves; (2) meeting at the edges without overlapping, as leaves or petals in the bud.
Variegated – Striped, margined, or mottled with a color other than green, where green is normal.
Variety – Subdivision of a species having a distinct though often inconspicuous difference, and breeding true to the difference. More generally also refers to clones.
Vascular bundle – A discrete group of conducting vessels.
Vascular bundle scar – A minute spot within the leaf scar where the vessels were positioned.
Velutinous – Clothed with velvety indumentum comprised of erect, straight, dense, moderately firm hairs.
W
Whorl – Arrangement of three or more structures arising from a single node.
Woolly – Having long, soft, more or less matted hairs; like wool.
X
× – indicates a hybrid.
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