| Word | Definition |
| Achene | A fruit with one seed, the fruit does not break open to expose or shed the seed. |
| Acidic | (of soils) with a pH value of < 6.5 |
| Admixture | Weed seeds mixed in with the harvested grain |
| Alkaline | (of soils) with a pH value of >7 |
| Allelopathic | The inhibition of growth of one plant species by another due to the release of chemical substances. |
| Alternate | (of leaves) growing up a stem first on one side and then the other, rather than immediately opposite each other |
| Alternately | (of leaves) growing up a stem first on one side and then the other, rather than opposite to each other |
| Annual | A plant in which the whole life cycle from germination to seed dispersal occurs in one year |
| Anther | The part of the stamen that bears the pollen |
| Anthesis | flowering |
| Apex | The top part of a cotyledon, leaf or fruit.. The section furthest away from the stem. |
| Arrow-shaped leaf | A basically diamond to triangular shaped leaf with lobes either side at the base. |
| Auricle | In grasses, a hook-like projection that wraps around the stem, at the end of the leaf sheath where the leaf blade meets the sheath |
| Awn | In some grass species, a bristle-like projection at the back or tip of a glume or lemma |
| Axil | The place where a leaf stalk or leaf blade meets the stem |
| Axis | The main stem of a plant, flowerhead or spikelet |
| Barbed | With sharp projections |
| Basal rosette | Acluster of leaves growing around the same stem node, usually near the ground |
| Beak | A long thin extension of the tip of a pod |
| Biennial | A plant which lives for two years, usually germinating in the first year and then flowering and producing seed in the second year, before dying |
| Biodiversity | The range of species found in a specific area |
| Biotype | A group of individuals within a species that are genetically distinct |
| Bipinnate | (of leaves) having both leaves and leaflets divided to the central vein |
| Blade | The part of a leaf above the sheath |
| Bolter | A plant that flowers earlier than others around it |
| Bract | Amodified leaf that is found in a flower or flowerhead |
| Bracteole | A little bract found for example around the smaller groups of flowers of fool’s parsley |
| Branch | Lateral growth from the main stem. |
| Break | A period between two similar crops when a different crop or no crop is grown |
| Break crop | A crop grown between two related crops, e.g. oilseed rape grown between two cereal crops |
| Bristle | A stiff hair, or very fine straight awn |
| Broad-leaved | For this encyclopaedia - not a grass |
| Bulbous | Swollen at the base of the stem, resembling a bulb |
| Calyx | The outermost group of flower parts, composed of sepals which may resemble small leaves |
| Calyx-tube | Where the sepals are fused at the base they form a calyx tube (for example in nettles). |
| Canopy | The parts of a plant, especially the leaves, that receive light from the sun and shade the ground beneath |
| Capsule | A fruit that dries and releases its seeds by splitting apart (as in mouse-ear) or by opening up small holes (as in poppy). |
| Cell | A section of a fruit, containing the seed |
| Cilia | Long, thin projections |
| Clasp | (of a usually stalkless leaf) to wrap around a stem |
| Clonal colony or clonal patch | A group of plants that are genetically identical and different from others growing around them |
| Coleoptile | (monocotyledons) The sheath covering the cotyledon |
| Compacted | (of soil) compressed by the passage of vehicles |
| Compact-flowerhead | (of flowerheads) having the individual flowers tightly packed together |
| Compact-plant | (of plants) having a neat growth habit |
| Competitiveness | The ability of a plant to grow successfully in relation to other plants around it |
| Composite | A plant that has flat flowers composed of florets arranged around a central structure, for example a daisy, dandelion or sunflower. |
| Compound | (of leaves) divided into completely separate leaflets to the central vein or centre of the stem |
| Corolla | The group of petals forming a flower |
| Corolla tube | A group of petals fused together for the whole or part of their length |
| Cotyledon | a green structure resembling a leaf that appears as a seed germinates, before the true leaves appear |
| Cross-fertile | Fertilised by receiving pollen from another plant. |
| Culm | Stem of grasses. |
| Dicotyledon | A plant whose seed produces a pair of seed leaves as it germinates. |
| Disc floret | a small tubular flower of which many are packed together in the flowerheads of plants such as thistle or in the centre of flowerheads such as those of daisy |
| Distribution | The geographical area throughout which a plant usually grows |
| Dormancy | The period during which a seed or bud is not actively developing |
| Downy | Covered with small soft hairs |
| Ear | The flowerhead of a grass, especially wheat or barley |
| Elliptical | Shaped like a flattened circle |
| Emergence | The germination of a seed, when the cotyledons appears above the ground |
| Entire | (of leaves) not toothed or lobed |
| Exploit | To spread into or colonise an area |
| Extend | To grow longer |
| Female flower part | A single female flower part is called a pistil and consists of the ovary, which will become the fruit, containing ovules, which will become the seeds. On top of the ovary is the style which connects the stigma, the surface on which where pollen is deposited |
| Filament | Stalk of anther. |
| Floret | A small flower that forms part of a flowerhead |
| Flowerhead | A group of small flowers on a single main stem |
| Folded | (of leaves) folded lengthwise about the central vein, with the uppermost leaf blade folded in |
| Folded leaves | Leaves folded lengthwise about the midrib. The upper most leaf blade folded in. |
| Fop' and 'dim' herbicides | Herbicides containing the chemicals diclofop and clethodim |
| Fruit | The part of a mature flower that carries or encloses the seeds |
| Glabrous | Without hairs. |
| Gland | A group of cells that secretes a sticky substance |
| Glandular | Having cells that secrete a sticky substance |
| Glaucous | Bluish-green in colour. |
| Glume | In grasses, the outer empty bract of a floret, usually found in pairs |
| Graminicide | A herbicide used for killing grass species |
| Groundkeeper | A plant that grows from a storage organ such as a potato tuber or a sugar beet accidently left in the ground after harvest |
| Habit | The characteristic way of growing of a specific type of plant |
| Habitat | The type of environment in which a specific plant grows |
| HBN herbicides | Herbicides containing the chemical hydroxybenzonitrile |
| Hemi-parasite | A plant that receives part of it’s food from the host on or with which it grows, while making some itself. As in red bartsia |
| Hemi-parasite | A plant that produces its own food by photosynthesis, but is able to extract water and minerals from the roots of the plants on which it grows, for example red bartsia |
| Herb | A plant that does not produce a woody stem |
| Herbaceous | Non-woody. Green and of soft texture. |
| Herbicide | A chemical used to kill plants, especially to control weeds |
| Hypocotyl | The stem supporting a cotyledon or pair of cotyledons |
| Infestation | The uncontrolled spread of weeds in an area |
| Inflorescence | The flowering head at the top of the stem. Also called a panicle, raceme or spike in grasses. |
| Keel - leaf blades | A sharp fold or ridge at the back of a leaf sheath, blade, glume or lemma |
| Keel-seed | The sharp long edge of a seed with a triangular cross section |
| Kidney-shaped | (Leaf or cotyledon) wider than long with a pronounced notch at the tip |
| Kidney-shaped | (of a leaf or cotyledon) wider than long with a pronounced notch at the tip |
| Lamina | The leaf blade. |
| Lance shaped | (Leaf or cotyledon) long and narrow tapering to a pointed tip |
| Lanceolate | Lance-shaped. (Wider in lowest third and narrower at tip) |
| Lance-shaped | (of a leaf or cotyledon) long and narrow, tapering to a pointed tip |
| Lateral | Growing at the side, or situated at the side |
| Lateral lobes | (of leaves) a division at the side |
| Latex | A milky substance, usually seen when stems are broken. |
| Leach | (of nutrients, chemicals etc.) To be washed out of the soil by rain or by irrigation |
| Leaflet | An individual part of a leaf that is divided |
| Lemma | In grass flowers, the lower of the two parts of a floret |
| Ley | An area of grass sown as part of a system of crop rotation |
| Ligule | An extension of the leaf sheath, where it joins the leaf-blade |
| Lip | The projections of the corolla of tubular or pea like flowers (as in red dead-nettle). |
| Lip | A projection on the lower part of a tubular flower such as pea or red dead-nettle |
| Lobe | A rounded division of a structure, e.g. A section of a divided leaf that is not cut as far as the middle, or part of a fruit |
| Mealy | Appearing to be spotted with or covered in white powder |
| Membranous | Thin, transparent and pliable |
| Micro-species | In some species such as dandelion, a group of plants that differ in their characteristics from other groups and reproduce asexually |
| Midrib | The central vein of a leaf |
| Monocotyledons | A plant whose seed produces only one seed leaf as it germinates |
| Neutral | (of soils) neither acidic nor alkaline, with a ph value of 7 |
| Node | A slight swelling on a stem or axis from which a leaf or bract grows |
| Nutlet | A small hard fruit |
| Oblong | Used to describe a flowerhead, leaf or cotyledon that is longer than it is wide with parallel sides |
| Ochrea | The membranous sheath that may surround the stem and leaf stalk as in redshank |
| Open | Used to describe a plant or a flowerhead in which the individual branches or flowers are not tightly packed together |
| Opposite | (of leaves) growing directly opposite each other on each side of a stem |
| Palea | The upper bract of a grass floret |
| Panicle | A loosely branched flowerhead |
| Pappus | A parachute of hairs at the top of the fruit of some plants such as dandelion and thistle |
| Perennial | A plant that lives for more than two years, flowering each year |
| Perianth | The group of calyx and corolla (sepals and petals). |
| Persistent | Remaining or growing for several years |
| Petal | The innermost leaf-like, usually coloured parts ofa flower surrounding male and female parts |
| Petiole | A leaf stalk |
| Phyllocron | the interval in thermal time from the emergence of one leaf tip on a shoot to emergence of the next |
| Pinnate | (of leaves) divided to the central vein |
| Pollination | The process of transfering pollen from anther to stigma in a flower |
| Pore | (in a seed head) a small hole or opening |
| Post-emergence | The period after the cotyledons have appeared |
| Predation | The eating of seeds that have fallen to the ground by small mammals, birds, etc. |
| Procumbent | Used when a plant lies loosely along the ground. |
| Prostrate | Growing flat along the ground |
| Raceme | Unbranched flower-head, with the spikelets stalked directly on the axis. |
| Ray | A branch of the smallest flower groups in umbelliferous flowers |
| Ray florets | One of the flowers making up the outer ring flowers of daisy-like flowerheads, with one long strap-shaped petal |
| Receptacle | The swollen top of a flower stalk which supports the individual flower parts ofa compound flower |
| Reflexed | Pointing downwards or backwards |
| Regenerate | To regrow |
| Rhizome | An underground stem that is covered with scale-like leaves and can root at the nodes |
| Rogueing | The removal of plants that are different from the required standard of the rest of the crop |
| Rolled leaves | Leaf blade rolled within the leaf sheath. |
| Rosette | A circular arrangement of leaves, all at one height, usually at the base of the plant on the ground |
| Rotation | A system of cultivation in which crops that have different nutrient requirements or are affected by different diseases are either grown one after the other or are interspersed with periods when no crop is grown |
| Row crop | A crop that is planted in separated rows, for example onion, lettuce or maize |
| Runner | A stem that grows along the ground and forms a new plant at the tip |
| Seed longevity | The length of time for which seed remains able to germinate |
| Seed rain | The quantity of seed shed from a plant |
| Seed set | The production of seeds |
| Seedbank | The quantity of seed remaining in the soil that is able to germinate |
| Self-fertile | (of a plant) able to be fertilised with its own pollen. |
| Sepal | The outer, usually green, leaves surrounding a flower |
| Set seed | To produce seeds |
| Sheath | The lower part of a leaf surrounding the leaf stem |
| Shed leaves | To lose leaves |
| Shed seed | To release seed |
| Simple | (of stems) unbranched (of leaves) not toothed or lobed |
| Solitary | (of a grass plant) having a single stem, rather than a group of stems |
| Species | A group of plants that can interbreed and have fertile offspring |
| Species | A group of plants that are so similar they can interbreed and have fertile offspring |
| Spike | An unbranched stalk of individual flowers, or groups of flowers (spikelets) |
| Spikelet | In grasses, a group of flowers, generally made up of two dry bracts (glumes) and one or more flowers |
| Spur | A projection from the back of a petal, as in field pansy |
| Stale seedbed | The technique of allowing weed seeds to germinate before cultivation, or before drilling or spraying with herbicide |
| Stamen | A single male part of a flower, consisting of an anther containing pollen and its stalk (filament) |
| Stigma | The sticky surface at the tip of the style which receives pollen |
| Stipule | A little scale, which may form at the base of a leaf, or a leaf stalk. In vetches as peas the cotyledons are hidden and the first projection on the stem is a stipule. |
| Stipule | A small scale, which may form at the base of a leaf or a leaf stalk |
| Stolon | A stem that grows along the ground and produces roots and shoots at the nodes |
| Stout | (of plants) strong or robust |
| Strap shaped | Leaf or petal which has parallel sides but is very much longer than wide |
| Strap-shaped | Used to describe a leaf or petal that has parallel sides but is very much longer than it is wide |
| Stubble cultivations | Shallow cultivations after harvest to create favourable conditions for the germination of the seeds of weeds and crop volunteers which can then be removed before or at planting |
| Style | The stalk which attaches the pollen receptor to the ovary of the flower |
| Sub-species | A division of a species, with distinctive characteristics |
| Sward | An area of grassland |
| Taproot | A thick main root growing downwards into the soil, with much smaller roots branching off it |
| Tendril | A thin clasping structure, developed from a stem, leaf or leaf stalk, that allows a plant to climb |
| Tepal | A fused petal and sepal, as seen in the flowers of goosefoots or redshanks |
| Thermal time | each day the mean temperature (average of maximum and minimum temperature) is calculated. Thermal time is the sum of these means for each day (above 0°C) of the period being observed . The measurement is expressed as day degrees (°C days) |
| Tiller | A stem of a cereal or other grass plant,To produce multiple stems |
| Tillering | The stage at which a cereal or other grass plant produces mutliple stems |
| Toothed | (of a leaf) having indentations along the edges |
| Trifoliate | A leaf with three leaflets as in clover |
| True leaves | The first leaves that are formed after the cotyledon leaves have appeared from the seed |
| Tuber | A swollen part of a root or underground stem, which is used to store food for a plant and from which new plants may grow |
| Tuft | A group of several stems of a grass plant, which may be closely or loosely clumped together |
| Tussock | A dense raised clump of grass |
| Umbel | A group of flowers arranged in a flat topped cluster with al the major flower stalks joining at a central point like an umbrella as in wild carrot. The smallest individual groups are called rays. |
| Umbellifer | A plant with a flat-topped flowerhead (umbel) in which all the main flower stalks join at a central point, like the spokes of an umbrella |
| Unwinged | (of a stem) having no outgrowth along its length |
| Vegetative | Used to describe reproduction from plant parts such as tubers or rhizomes |
| Vein | (of a leaf or leaflet) having thickened and prominent vessels that transport food and water |
| Vigorous | Growing strongly |
| Vigour | The rate at which seeds germinate and seedlings grow |
| Volunteer | A plant that has not been deliberately sown or planted |
| Whorl | A set of three or more leaves growing from the same stem node and arranged in a circle |
| Wing | An outgrowth on a stem or seed case |