Tree Terms


Abscission layer - layer of cells that forms at the base of each leaf petiole where it is attached to the twig when the veins that carry fluids into and out of the leaf gradually close off.

Alternate - leaves that are staggered or not placed directly across from each other on the twig.

Anthers - sac-like component of a flower where pollen grains are produced. The anthers open to release pollen.

Anthocyanins - pigments in plants responsible for pink and purple colors.

Bark - outward covering of the tree.

Base - where the point at which the leaf is joined to the stem.

Broadleaf - A tree with leaves that are flat and thin and generally shed annually.

Calyx - the outermost whorl of sepals whose job is to protect a developing flower. It is usually green and is what we would recognize as the outside covering of a bud.

Cambium - layer which forms across and between primary bundles where each year cells in this layer divide and grow. As the cambium divides, wood and bark cells form.

Carotenoids - pigments in plants responsible for yellow and orange colors.

Carpel - the female part of the center whorl of a flower. Also known as the pistil.

Chlorophyll - the green pigment in plants that absorbs energy from sunlight necessary for photosynthesis.

Chloroplast - the organelle in the cytoplasm of plant cells where chlorophyll is stored.

Compound - a leaf whose blade is divided into distinct leaflets.

Conifers - cone-bearing trees where the seeds are present in cones or catkins.

Corolla - the whorl of petals of a flower.

Deciduous - shedding all leaves annually.

Evergreen - trees with needles or leaves that remain alive and on the tree through the
winter and into the next growing season.

Fertilization - joining of a sperm to an egg cell. Results in an embryo which triggers development of a seed.

Filaments - thread-like structures that support the anthers out from the flower base.

Heartwood - the inner part of the wood; also called duramen.

Lamina - the wide part of the leaf; also called the leaf blade.

Leaflet - one of the subdivisions of a compound leaf.

Opposite - 2 or 3 leaves that are directly across from each other on the same twig.

Ovary - The inner part of carpel or pistil where eggs are borne.

Palmate - having leaflets radiating out from a central point.

Pedicel (Pedicuncle) - the flower stem.

Petals - outer part of a flower; protects the inside parts of a flower.

Petiole - thin section of leafstalk joining the base of the leaf to the lamina; generally is cylindrical or semicircular in form. Also called the stalk.

Phloem - a protective layer made up of tiny tubes that transport the sugars from the leaves to the rest of the tree.

Photosynthesis - the process by which plants make sugar from sunlight, water, and carbon dioxide.

Pinnate - having leaflets on both sides of a common axis.

Pistil - Female part of a flower; also known as the carpel.

Pollination - the movement of pollen from a stamen to a pistil by pollinators (birds or insects).

Provascular tissue - bundles of cells in young tree shoots.

Root hairs - threadlike extensions that grow from a plant root and takes in water and minerals from the soil.

Roots - anchors the tree to the soil and absorbs water and soil minerals.

Sapwood - the outer part of the wood; also called alburnum.

Senescence - death of a leaf triggered by an increase in the enzymes that promote the breakdown of plant cells. Begins when shorter days and cooler temperatures occur.

Sepals - the separate parts of the flower calyx that is the outside covering of a bud.

Simple - a single leaf blade with a bud at the base of the leafstem.

Stamen - the male part of a flower that makes pollen.

Stigma - The sticky surface of a flower pistil on which pollen adheres during pollination.

Stomata - openings in a leaf through which gases and water enter or leave.

Style - extending from the center of a flower, it supports the stigma where pollen adheres during pollination.

Tannins - pigments in plants responsible for brown colors.

Xylem - the main part of the tree trunk made up of tiny tubes which transport water and minerals from the roots up the trunk and branches to the leaves.