• Angiosperm – flowering plant that bears ovules, later seeds, enclosed in ovaries (as opposed to a gymnosperm, which bears naked ovals, then seeds, in cones).

• Anther – part of the stamen that releases pollen; usually borne on a filament.

• Aril – coat covering some seeds, often fleshy and brightly coloured.

• Axillary – borne in an axil (see also Terminal).

• Basal – at the base of an organ or structure.

• Biennial – Plant that completes its life-cycle in 2 years, growing in the first year, and flowering and fruiting in the second.

• Bipinnate (2--pinnate) see Pinnate

• Bract – modified leaf at the base of a flower or flowerhead. May be small and scale-like, or large, brightly coloured, and petal-like, or resemble normal foliage.

• Bracteole – secondary bract sheathing a flower in an inflorescence, itself enclosed within a primary bract.

• Bulbous – 1. Used to describe a stem that is swollen at the base, usually underground. 2. Describes a plant with bulbs. 3. Loosely refers to a plant with an underground storage organ such as a bulb, corm, tuber, or rhizome.

• Calyx (pl. calyces) – collective name for sepals, joined or separate, which form the outer whorl of the perianth.

• Carpel – female part of a flower consisting of a style, a stigma, and an ovary.

• Chlorosis (adj. chlorotic) – loss of chlorophyll, and consequently the loss of green leaf colouration, caused by mineral deficiency, poor light levels, or disease.

• Cleft – divided almost halway to the centre.

• Corolla – 1. Collective name for petals. 2. Inner whorl of perianth segments in some monocotyledons.

• Corymb – broad, flat-topped or domed inflorescence of stalked flowers or flower-heads arising at different levels on alternate sides of an axis.

• Crest – 1. Tuft of hairs or soft bristles. 2. Raised ridge on a surface.

• Cultivar (abbrev. cv., contraction of "cultivated variety") – plant raised or selected in cultivation that retains distinct, uniform characteristics when propagated by appropriate means.

• Cyme – flat or round-topped, branched inflorescence with each axis ending in a flower, the oldest at the centre, and the youngest arising in succession from the axils of bracteoles.

• Deciduous – 1. Shedding leaves annually at the end of the growing season. 2. Falling away when no longer functional, as with the petals of many flowers.

• Ellipsoid – Used to describe a solid form, broadest at the centre, tapering towards each end; length is 2 times the width. It is wider than a spindle-shaped form, with the side more curved.

• Elliptic – used to describe a flat structure, broadest at the centre, tapering towards each end; length is 2 times the width.

• Evergreen – 1. Retaining leaves for more than one growing season. 2. Plant with the above characteristic.

• Fasicle (cluster) – arrangement of several inflorescences, leaves, stems, roots or flowers that arise from a single point, or appear to do so.

• Fertile – 1. Refers to organs that produce functional pollen, spores, or viable seed. 2. Used to describe the soil with a high content of nutrients essential to plant growth.

• Filament – 1. Stalk of the stament attached to the anther. 2. Thread-like extension or hair.

• Frond – 1. Leaf of a fern. 2. Loosely, a large, compound leaf, such as a palm leaf.

• Glaucous – with a blue-green, blue-grey, grey or white bloom; usually refers to stems and leaves.

• Gymnosperm – tree or shrub, generally evergreen, that bears naked seeds in cones rather than enclosed in ovaries, e.g. conifers, cyads.

• Herbaceous border – area of land set aside for the cultivation of herbaveous plants.

• Herbaceous plant – non-woody plant that dies back (loses top-growth and becomes dormant) at the end of the growing season, usually in autumn, overwintering by means of underground rootstocks, some may develop a woody base. Growth resumes in spring.

• Hybrid (cross) – naturally or artificially produced offspring of genetically distinct parents of different taxa. Hybrids show new characteristis and are often vigorous in growth.

• Incised – deeply, irregularly, and sharply toothed or lobed

• Indusium (pl. indusia) – tissue covering a sorus on a fern frond.

• Inflorescence – arrangement of flowers on a single axis.

• Invasive – used to describe a vigorous plant that rapidly overwhelms more delicate neighbours, unless restricted in spread.

• Inversely lance-shaped (oblanceolate) – broadest above the centre, tapering to a narrow basi point; lenght is 3-6 times the width.

• Lanceolate – see Lance-shaped.

• Lance-shaped (lanceolate) – broadest below the centre, tapering to a narrow tip; length is 3-6 times the width.

• Lax – loose, not compact.

• Leaf-stalk (petiole) – part of a leaf, attached to the base or centre of the leaf-blade, that connects it to a stem or branch.

• Leaflet – single division of a compound leaf. Botanically, a pinna.

• Linear – long and narrow, with parallel margins, or almost so; length is 12 or more times the width.

• Lobe – usually rounded segment, separated from adjacent segments by clefts extending halfway or less to the centre of an organ, such as a leaf.

• Monocarpic – refers to plants that flower and fruit once and then die. Monocarpic perennials may grow for several or many years before flowering.

• Monocotyledons – Angiosperm with a single seed-leaf, parallel-veined leaves, no cambium layer, and floral parts usually in threes.

• Mucronate – of a round leaf that is abruptly terminated by a short tip.

• Oblong – with 2 parallel sides of roughly equal length. length is 2-4 times the width.

• Obovate – refers to a flat form, egg-shaped in outline and broadest above the middle; length is 1½ - 2 times the width.

• Oval – broadly elliptic, rounded at both ends, with slightly parallel sides in the middle; length is 1½-2 times the width.

• Ovary – female organ of a flower, containing ovules.

• Ovate – refers to a flat form, egg-shaped in outline and broadest below the middle; length is 1½ times the width.

• Ovule – part of the ovary from which seed develops after fertilisation.

• Palmate – used to describe a compound leaf that is fully divided into leaflets arising from a single basal point; it is often also used loosely to mean lobed in a hand-like form.

• Panicle – branched raceme. Loosely applied to freely branched, corymb-like or cyme-like inflorescences.

• Perennial – plant that lives for more than 2 growing seasons; in horticulture usually only applied to non-woody plants.

• Perianth – collective term for the corolla and calyx, whether these are distinct from each other or undifferentiated.

• Petiole see Leaf-stalk

• Pinna (pinnae) – leaflet of a pinnate leaf or of a fern frond. See also Pinnate.

• Pinnate – used to describe a compound leaf with leaflets (pinnae) arranged alternately or in opposite pairs on a central axis, with or without terminal leaflet. 2-pinnate (bippinate) leaves have pinnately divided leaflets. 3-pinnate (tripinnate) leaves have pinnately divided leaflets that are themselves pinnately divided.

• Pinnatifid – used to describe a simple leaf with usually opposite pairs of lobes cut no deeper than halfway to the midrib.

• Pinnule – see Segment

• Pistile – female reproductive organi of a flower, composed of one or several fused or separate carpels.

• Raceme – inflorescence of stalked flowers radiating from a single, unbranched axis, the youngest flowers near the tip.

• Rhizome (adj. rhizomatous) – horizontal, usually branching and fleshy stem, growing underground or, less often, at ground level.

• Rosette – 1. Dense whorl of leaves arising from the central point or crown of a plant, usually at or near ground level. 2. Whorled arrangement of petals or tepals.

• Salverform – used to describe a flower with a long, slim, tubular corolla that spreads out into more or less horizontal, flat lobes.

• Scape – leafless stem of a solitary flower or inflorescence.

• Scree – 1. Slope of unstable, rocky fragments, with excellent drainage, but often with freshwater springs running beneath, found on mountainsides and at the bottom of mountain cliffs and escarpments. 2. In gardens, a deep layer of stone chippings with a small proportion of loam, providing very sharp drainge for alpines and rock plants.

• Segment – 1. Subdivision of pinna on a pinnate leaf or frond; botanically known as a pinnule. 2. Any division of an organ, such as the lobe of a leaf or flower.

• Self-fertile (self setting) – used to describe a plant that does not need pollen from a second individual in order to fertilize and set fruit.

• Self-setting – see self-fertile.

• Sepal – one part of the calyx, when it is composed of separate parts. Usually green and smaller than petals, but sometimes colourful and petal-like.

• Serrate – used to describe a finely toothed margin, usually of a leaf, with the teeth slightly curved as in a saw blade.

• Sorus (pl. sori) – cluster of sporangia usually on the underside of a fern frond, almost always surrounded or covered by an indusium.

• Sporangium (pl. sporangia) – spore-producing organ on the underside of the fronds of all ferns and other members of the order Pteridophyta.

• Spore – basic unit of reproduction in many non-flowering plants, such as ferns, fungi and mosses.

• Sport (mutation) – natual or induced genetic change, often exhibited as a variegated shoot or flower from the parent plant. Sports may be vegetatively propagated to give rise to new cultivars.

• Stamen – male part of a flower, composed of an anther, normally borne on a filament.

• Sterile – refers to any flower that is incapable of producing seeds. 2. Applied to trees in which the flowers may be self-sterile. 3. Refers to soils that have been deliberately treated with a chemical to kill weed seeds, pests, and diseases.

• Stigma – tip of the pistil, which receives pollen to fertilize the ovules.

• Stolon (adj. stoloniferous) – arching, horizontal or trailing stem producing roots and new shoot at its tips.

• Style – part of the carpel or pistil connecting the ovary and the stigma.

• Tepal – petal or sepal of a flower, where the calyx and corolla are not clearly distinguished.

• Terminal – located at the end of a stem, shoot, or other organ (See also Axillary).

• Toothed (dentate) – used to describe a margin, usually of a leaf, with tooth-like triangular indentations. Doubled-toothed margins have alternate large and small teeth.

• Tripinnate – see Pinnate.

• Truss – compact cluster of flowers or fruit, particularly of rhododendrons.

• Umbel – flat or round-topped inflorescence in which numerous stalked flowers are terminally borne from a single point.

• Variegation– irregular arrangement of pigments, usually as a result of mutation or sometimes disease.

Sources
• "The New Encyclopedia of Hostas" by Diana Grenfell & Michael Shadrack
• The Royal Horticultural Society "A-Z Encyclopaedia of Garden Plants K-Z", pages 1118-1125

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