Glossary of terms

Below are a list of common plant terms that you may not be familiar with - there is a return link at the end of each Alphabetical section to take you back to the last page (or you can use the 'back button' in your browser):

Achene: A small, dry one-seeded fruit that does not open to release the seed.
Acid soil: See 'pH' below
Acuminate: Of a plant (eg a leaf): tapering to a point.
Alkaline soil: See 'pH' below
Annual plant: Plants with a life cycle that lasts only one year. They grow from seed, bloom, produce seeds and die in one growing season. They then need to be replanted each spring. Most annuals bloom for a long time.
(see also 'biennial', 'perennial' and 'triennial' below).
Apiculate: Tipped with a short, abrupt point, as a leaf.
Arid: Having little or no rain; too dry or barren to support vegetation.
Armature: Protective covering or structure of a plant, such thorns, serving for defence or offence.
Axil / Axils: The upper angle between a leaf stalk or branch and the stem or trunk from which it is growing.
Bark: Bark is the outermost layers of trunks, stems and roots of woody plants. Plants with bark include trees, woody vines, and shrubs.
Biennial plant: Lives for two growing seasons before setting seed and dying.
(see also 'annual' above and 'perennial' and 'triennial' below).
Bonsai: The art of growing ornamental, artificially dwarfed varieties of trees and shrubs in pots.
Bract / Bracts: A modified leaf or scale, typically small, with a flower or flower cluster in its axil. Bracts are sometimes larger and more brightly coloured than the true flower, as in poinsettia. a type of leaf that grows from a stem where the flower develops.
Branchlet: A small branch or division of a branch (especially a terminal division); usually applied to branches of the current or preceding year. sprig, twig.
Calyces / Calyx: The sepals of a flower, typically forming a whorl that encloses the petals and forms a protective layer around a flower in bud.
(see also 'sepals' and 'whorl' below)
Capsule: A capsule is a type of simple, dry fruit produced by many species of flowering plants:
1. In most cases at maturity the capsule splits apart to release the seeds within.
2. In some cases, such as those of poppies, seeds are released through openings or pores that form in the capsule. Examples of plants that produce capsules are nigella, poppy, lily, orchid, willow, cotton, and jimson weed.
3. In the Brazil nut, a lid on the capsule opens, but is too small to release the dozen or so seeds (the actual 'Brazil nut' of commerce) within. These germinate inside the capsule after it falls to the ground.
4. Capsules are sometimes mislabelled as nuts, as in the example of the Brazil nut or the Horse-chestnut. A capsule is not a nut because it releases its seeds and it splits apart. Nuts, on the other hand, do not release seeds as they are a compound ovary containing both a single seed and the fruit. Nuts also do not split.
Compost: The rich black soil-like result of decomposed leaves and other plant materials. Compost is high in organic matter content and is the perfect plant food, soil amendment and disease fighter.
(see also 'mulch', 'pH' and 'soil' below)
Concave: Curved or rounded inwards - like the interior surface of a sphere or circle.
Convex: Curved or rounded outwards - like the exterior surface of a sphere or circle.
Corm: An enlarged, fleshy, bulblike base of a stem, as in the crocus.
Cormous is used to describe plants growing from corms.
Corolla: The petals of a flower, typically forming a whorl within the sepals and enclosing the reproductive organs.
(see also 'sepals' and 'whorl' below)
Cultivar / Cultivars: A plant variety that has been produced in cultivation by selective breeding. Cultivars are usually designated in the style: Taxus baccata 'Variegata'.
Cutting: Also known as 'striking' or 'cloning', this is a technique for propagating plants in which a piece of the stem or root of the source plant is placed in a suitable medium such as moist soil, potting mix, coir or rock wool.
Cyme / Cymes: Flat-topped or convex flower cluster.
(see also 'convex' above)
Deciduous: Of a tree or shrub: shedding its leaves annually
(see also 'evergreen' and 'semi-evergreen' below).
Dendrology: The science and study of trees and woody plants, eg trees, shrubs, and lianas (woody climbing plants that hangs from trees), specifically their taxonomic classifications.
Dendrologist is someone who studies wooded plants.
Dissected: Divided into many deep, narrow segments: eg dissected leaves.
Downy: Covered with fine, soft hair.
Down: fine, soft hair.
Evergreen: A plant that retains green leaves throughout the year.
(see also with 'semi-evergreen' below and 'deciduous' above).
Exfoliating; Exfoliation (from the term 'foliate', meaning 'related to leaves') means the removal or loss of leaves from a plant. It is used both to describe the loss of a leaves as a natural part of a plant's life cycle (such as in the case of deciduous trees which lose their leaves in the autumn) or because of some trauma or outside cause (such as dehydration, an infestation of caterpillars or hurricane-force winds).

In arboriculture, the term 'exfoliating bark' describes the natural process and condition of the bark peeling-away from a tree trunk, typically in large pieces that remain partially attached to the trunk until such time as they are completely detached by the elements or the eventual and subsequent exfoliation of additional layers of bark.

Fissure / fissured: Split or crack (something) to form a long, narrow opening. A natural cleft between parts of an organ or plant.
Flannelly Resembling flannel.
Foliage Plant leaves collectively. The leaves of a plant or tree, or leaves on the stems or branches on which they are growing.
Genus (plural genera): Genus: refers to the group to which the plant belongs.
Species: particular member of group or genus. Usually descriptive.
Variety (var.): A natural occurring population of plants of one species, different enough from that species to require a different name

Species which share a number of significant features are grouped together to form a genus (plural genera). The characteristics of a genus are often quite easy to recognise, making this perhaps the most generally useful level at which plants can be identified for practical purposes.
Glabrous: Free from hair or down; smooth.
Glaucous: Is used to describe the pale grey or bluish-green appearance of the surfaces of some plants (from the Latin 'glaucus', meaning 'bluish-grey or green', from the Greek 'glaukós').
Grafting: A shoot or bud of one plant that is inserted into or joined to the stem, branch, or root of another plant so that the two grow together as a single plant. Grafts are used to strengthen or repair plants, create dwarf trees, produce seedless fruit, and increase fruit yields without requiring plants to mature from seeds.
Hardy / Hardiness: Able to survive outside during winter - see also Hardiness ratings on the RHS website.
Herbaceous plants: Are plants that have no persistent woody stem above ground. Herbaceous plants may be annuals, biennials or perennials. In botanical use frequently simply herbs.
Humus-rich soil: Soil that is rich in organic matter, whether from added compost or the natural decomposition of plant material.
(see also 'compost' above and 'mulch, 'pH' and 'soil' below)
Hybrid / Hybrids: The offspring of two plants of different species or varieties (cross-breed).
Inflorescence: The complete flower head of a plant including stems, stalks, bracts, and flowers - composed of a main branch or a complicated arrangement of branches.
(see also 'bracts' above)
Lacecap: A hydrangea of a group of varieties that have flat flower heads with fertile florets in the centre surrounded by sterile florets.
Lanceolate: Shaped like a lance head; of a narrow oval shape tapering to a point at each end.
Laurel forest: Also called 'laurisilva' or 'laurissilva', is a type of sub-tropical forest found in areas with high humidity and relatively stable, mild temperatures. The forest is characterized by broadleaf tree species with evergreen, glossy and elongated leaves.
Layering: A method of propagating a plant in which a shoot is fastened down to form roots while still attached to the parent plant.
Leaflet: Each of the leaf-like structures that together make up a compound leaf, such as in the ash and horse chestnut (see also 'trifoliate' below).
Loam: A fertile soil of clay and sand containing humus; a soil with roughly equal proportions of sand, silt, and clay.
(see also 'humus' above)
Lobe / Lobes: A roundish and flattish projecting or hanging part of something, typically one of two or more such parts divided by a fissure - eg the leaf has a broad central lobe.
Monoecious: Having both the male and female (unisexual) reproductive flowers, with the flowers of both sexes carried on a single plant, as in corn.
Mophead flowers: Are large round flower heads resembling pom-poms or, as the name implies, the head of a mop, that can that stretch up to about 30cm (12 inches) across.
Mulch: Material (such as decaying leaves, bark, or compost) spread around or over a plant to enrich or insulate the soil.
(see also 'compost' above and 'pH' and 'soil' below)
Neutral soil: See 'pH' below.
Nutlet / Nutlets a small nut, especially an 'achene' (see above).
Obovate: Of a leaf: ovate with the narrower end at the base (see also 'ovate' below).
Orbicular: Having the shape of a flat ring or disc, or having a spherical or rounded shape.
Ovate: Shaped like an egg and flat, with the broad end toward the base, eg an ovate leaf.
Panicle / Panicles: A loose branching cluster of flowers, as in oats.
Pedicellate: A flower having a stalk.
Pedicel / Pedicels: A small stalk bearing an individual flower in an inflorescence.
(see also 'inflorescence' above)
Pedunculate: A flower having a stalk.
Pendant: Hanging down, drooping.
Pendulous: Hanging down loosely, drooping.
Perennial plant: Lasting or existing for a long time; enduring or continually recurring
(see also 'annual', 'biennial' and 'triennial' below).
Perianth: Sometimes called 'perigonium' or 'perigon', is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals).
(see also 'calyx' and 'corolla' above, and 'petals' and 'sepals' below)
Petal: One of the often brightly coloured parts of a flower surrounding the reproductive organs. As a group, the petals are called the corolla.
(see also 'corolla' above)
Petalled: Having, or with, petals. Having the number, or colour, of petals that is mentioned: eg a six-petalled yellow flower.
Pinnate: Of a compound leaf: having leaflets arranged on either side of the stem, typically in pairs opposite each other.
(see also 'leaflets' above)
pH - soil pH: Different plants thrive in different soil types, the soil pH is a number that describes how 'acid' or 'alkaline' your soil is:
  a pH of 7.0 is considered 'neutral'
  a pH below 7.0 is considered to be 'acid'
  a pH above 7.0 is considered to be 'alkaline'
See also: Soil - understanding pH and testing soil on the RHS website
Raceme / Racemes: An unbranched, indeterminate type of inflorescence bearing pedicellate flowers; flowers having short floral stalks called pedicels - along its axis. In botany, an axis means a shoot, in this case one bearing the flowers; flower cluster with the separate flowers attached by short equal stalks at equal distances along a central stem, the flowers at the base of the central stem develop first.
(see also 'inflorescence', 'pedicellate' and 'pedicels' above)
Runner: A slender creeping branch of a plant that roots at the end or at the joints to form new plants.
Scurf / Scurfy: A covering that resembles scales or bran that covers some plant parts, Rough to the touch; covered with scales or scurf.
Semi-evergreen: 1. having functional and persistent foliage during part of the winter or dry season.
2. tending to be evergreen in a mild climate but deciduous in a rigorous climate
(see also 'evergreen' and 'deciduous' above)
Sepal / Sepals: Each of the parts of the calyx of a flower, enclosing the petals and typically green and leaf-like.
(see also 'calyx' above)
Seta / Setae: A stiff hair-like or bristle-like structure, (in a moss or liverwort) the stalk supporting the capsule.
(see also 'capsule' above)
Shrub: A woody plant which is smaller than a tree that has several main stems arising at or near the ground.
Soil: The basic term for what's already there; a.k.a. your 'dirt'. Most un-amended soils contain lots of sand or clay, and their organic matter content is generally very low.
(see also 'compost', 'humus rich soil', 'mulch' and 'pH' above)
Stamen / Stamens: The male fertilizing organ of a flower, typically consisting of a pollen-containing anther and a filament.
Stipule / Stipules: A small leaf-like appendage to a leaf, typically borne in pairs at the base of the leaf stalk.
Stolon / Stoloniferous: A prostrate stem at, or just below, the surface of the ground, that produces new plants from buds at its tips or nodes.
Taxonomic / Taxonomy: The science of classification according to a pre-determined system, with the resulting catalogue used to provide a conceptual framework for discussion, analysis, or information retrieval (from Greek 'taxis' meaning arrangement or division, and 'nomos' meaning law)
Topsoil: The uppermost 15 to 30 centimetres of a soil; that is, 'the top of the soil'. In the woods, this would be the most humus rich portion.
(see also 'humus' above)
Triennial plant: Lives for three growing seasons before setting seed and dying.
(see also 'annual', 'biennial' and 'perennial' above)
Trifoliate: Of a compound leaf: having three leaflets - trifoliate leaves.
(see also 'leaflet' above)
Truncate: Of a leaf: ending abruptly as if cut off across the base or tip.
Tuber: A much thickened underground part of a stem or rhizome, eg in the potato, serving as a food reserve and bearing buds from which new plants arise.
Tuberous: of the nature of a tuber
Understory: The understory is the underlying layer of vegetation in a forest or wooded area, especially the trees and shrubs growing between the forest canopy and the forest floor. Plants in the understory comprise an assortment of seedlings and saplings of canopy trees together with specialist understory shrubs and herbs.
Variegated: Having or consisting of leaves that are edged or patterned in a second colour, especially white as well as green.
Whorl: A pattern of spirals or concentric circles.

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