Linda M. Wilson, Cynthia Jette, John Connett, Joseph P. McCaffrey. 2003. Biology and Biological Control of Yellow Starthistle. USDA Forest Service FHTET-1998-17 2nd Ed.

Glossary

achene – A small, one-seeded fruit that does not split at maturity.

alternate – Leaves that are arranged singly along a stem; one leaf or bud at each node on alternate sides of the stem.

aspirator – An apparatus used to suck insects into a container. Can be as simple as in a mouth-aspirator, or mechanical as in a gasoline- or battery-powered vacuum aspirator.

basal – At the base of a plant or plant part.

biennial – A plant which lives two years.

biological control – The intentional use of a weed’s natural enemies for control purposes. Also referred to as biocontrol.

bolting – Plant stage at which the flower stalk begins to grow.

bract – A small, leaf-like structure below a flower.

capitulum (pl. capitula) – Seedhead of plants in the sunflower family.

coordinate – Any of a set of numbers used to specify a point on a line, or an intersection of 2 lines.

cotyledon – First leaf-like structures that appear after germination; seed leaves.

density – Number of individuals per unit area.

diapause – Period of dormancy in insects.

dissemination – Dispersal. Can be applied to seeds or insects.

duff – Partly decayed organic matter on the forest floor.

entire – Leaf margins that are not cut or toothed.

elytron (pl. elytra) – Hardened front wings of a beetle.

emergence – Act of adult insect leaving the pupal exoskeleton, or from winter dormancy.

exoskeleton – External skeleton of the body of an insect.

floret – One of the small, closely clustered flowers forming the head of a composite flower in the sunflower family.

frass – Plant fragments, usually mixed with excrement, deposited by feeding insects.

gall – An abnormal growth on a plant, usually induced by an insect that lives in the gall.

grub – A soft, thick-bodied, C-shaped beetle larva.

head – A group of flowers borne tightly together.

host specificity – The highly-evolved, often obligatory association between an insect and its host: (i.e., weed).

inflorescence – The flowering arrangement of a plant, as in panicle or raceme.

instar – The phase of an insect’s development between molts.

involucre – A circle of bracts under an inflorescence.

larva (pl. larvae) – Immature insect stage between the egg and pupa.

lobed – A leaf with deeply or shallowly-rounded segments, as in a starthistle rosette leaf.

metabolic sink – Site of the plant that receives photosynthate (food) produced by the plant, diverting the resource from the plant’s normal use.

metamorphosis – In insects, a change in form during development.

molting – Process of insect development that involves shedding its exoskeleton and producing a new exoskeleton for the life stage.

mottled – Surface having colored spots or blotches.

multivoltine – Two or more generations per year, as in starthistle flies.

oviposit – To lay or deposit eggs.

pappus – A tuft of hairs, scales or bristles at one end of a seed, as in a thistle plume, used to aid seed dispersal.

phytophagous – Plant eating.

proleg – A fleshy, unsegmented, abdominal walking appendage of some insect larvae.

pubescence – Hairs or bristles covering a leaf, stem, or flower.

pupa (pl. pupae) (v. pupate) – Non-feeding, inactive stage between the larva and adult in insects.

quadrat – A specific area used for sampling (e.g., 1 square meter).

qualitative – Measurement of descriptive elements (e.g., age class, distribution)

quantitative – Measurement of quantity - number or amount (e.g., number of seeds per plant, number of larvae per seedhead).

receptacle – Part of the capitulum to which flowers are attached.

rosette – A round, compact, normally basal cluster of leaves in a juvenile plant.

senescence – Final stage in a plant’s lifecycle.

snout – ‘Nose’ of a weevil. The elongate head of a weevil with mouth parts at the apex (tip).

spine – A stiff, pointed plant part.

synchrony – Occurring at the same time, i.e. flowering and insect oviposition.

thorax – Body region of an insect between the head and abdomen, bearing the legs and wings.

transect – A straight line of varying length along which plants are sampled individually or in quadrats.

univoltine – One generation per year, as in starthistle weevils.

variable – A quantity that can have more than one of a set of values (e.g., plant height).

weevil – A type of plant-eating beetle; the adult has a long snout and the larva is a C-shaped grubs (a.k.a. snout beetle).

x-axis – Horizontal axis or line in a coordinate system.

y-axis – Vertical axis or line in a coordinate system.

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