Tree Glossary

Get yourself familiar with the terminology and definition related to trees. (Updating on regular basis)

A

Acid

Having a pH level below 7.

Alkaline

Having a pH level above 7.

Allelopathy

The suppression of growth of one plant species by another due to the release of toxic substances.

Alternate

Leaves that are staggered, not placed directly across from each other on the twig.

Anthracnose

A group of fungi that cause dieback and sometimes death to various species such as dogwoods, sycamores, oaks and maples.

Achene

A small, dry and hard one-seeded fruit.

Acorn

A nut-like fruit of an oak with a scaly or warty cap.

Alternate leaves

The leaves arranged on alternating sides of the twig.

Angiosperm

The class of plants that has the seeds enclosed in an ovary; includes flowering plants.

Annual rings

A layer of wood – including spring-wood and summer-wood – grown in a single season; best seen in the cross-section of the trunk.

Awl-like leaves

The short leaves that taper evenly to a point; found on junipers and redcedars.

B

Berry

It’s a fleshy fruit with several seeds.

Bisexual flower

A perfect flower; a flower with organs of both sexes present.

Blade

The flat part of a leaf or leaflet, characteristic of broadleaf trees.

Bract

A modified leaf that bears a flower.

Broadleaf

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

Bud Scar

The marks remaining after bud scales drop in the spring.

C

Capsule

A dry fruit that splits open, usually along several lines, to reveal many seeds inside.

Clingstone

Any of various stone fruits (such as some peaches or plums) with flesh that adheres strongly to the pit.

Cambium

A single layer of cells in the tree’s trunk that produces the new wood and bark.

Compound Leaf

A leaf with more than one blade. All blades are attached to a single leaf stem. Where the leaf stem attaches to the twig, there is a bud.

Conifer

A cone-bearing tree.

Cross Pollination

Fertilization between genetically compatible trees for better fruit, often resulting in superior offspring.

Crown of the tree

The head of foliage of a tree or shrub. This is the form or shape of the tree. Such as branches, twigs, buds, leaves, flowers and fruit.

D

Deciduous

A tree that shed all leaves annually. Or the leaves drop in the autumn. Not evergreen trees.

Dichotomous

A key to tree identification based on a series of decisions, each involving a choice between two alternate identification characteristics.

Diffuse-porous

A type of hardwood in which vessels in the spring-wood are the same size as vessels in summer-wood (maples, birches, poplars, etc.).

Dioecious

This means having unisexual flowers with staminate (male) and pistillate (female) flowers borne on different trees.

Drupe

A fleshy fruit with a single stone or pit.

E

Entire leaf

A leaf margin with smooth, untoothed edges.

An Elliptic leaf

This resembling an ellipse and about one-half as wide as long.

Entire margin

This is a leave margins that are smooth (not toothed).

Evergreen

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

Exfoliate

Peeling in shreds or thin layers, as bark from a tree.

F

Family

A group of closely related species and; scientific name ends in “aceae”.

Forest ecology

This is a study of the occurrence of forest plants and animals in respect to their environment.

Freestone

A fruit stone to which the flesh does not cling.

Fascicle leaf

A cluster of conifer leaves

Fruit

The seed-bearing part of a tree

G

Genus

This is a group of species that are similar; the plural of genus is genera.

Glabrous

Smooth, with no hair or scales.

Gymnosperm

This is a large class of plants having seeds without an ovary, usually on scales of a cone; includes conifers and the ginkgo.

H

Habit

The general mode of plant growth. Used to describe the overall shape of a tree.

Habitat

The place where a plant usually grows, e.g., a rocky, moist, well-drained, etc

Hardwood

Term used to describe all broadleaved trees. These tree species are deciduous, retaining their leaves only one growing season. Despite the term, some “hardwoods” such as the aspens, have wood that is relatively soft.

Hardiness Zone

A plant can be expected to grow in the zone’s temperature extremes, as determined by the lowest annual temperature. Other conditions such as moisture, soil and wind might affect the availability of individual plants.

Heartwood

The area next to the pith, which is composed of deal cells and serves as support.

I

Inner bark (phloem)

Conducts usable food from the leaves to the cambium to nourish it or to storage areas in the wood.

Inflorescence

This is the flowering portion of a plant.

K

Tree Knees

The tree trunk in wet conditions exhibits a broad buttress with protrusions from the roots.

L

Lanceolate

This is lance-shaped; about 4 times as long as wide and widest below the middle. A leaf shaped like a lance head; tapering to a point at each end. simple leaf – a leaf that is not divided into parts.

Lateral buds

These buds mainly found along the length of the twig (not at the tip); they occur where the previous year’s leaves were attached.

Leaf

Stalk and blade of hardwoods: needles and scales of conifers.

Leaflets

Smaller leaf units or leaflets which together form a compound leaf.

Leaf scar

The mark left on the twig where the leaf was previously attached.

Legume

A dry, elongated pod that splits in two, with seeds attached along one edge inside.

Lobed margin

Projections that shape a leaf.

M

Margin

The edge of a leaf.

Midrib of a leaf

The primary rib or central vein of a leaf.

Medullary or wood rays

These rays radiate out from the center of the tree, and serve in lateral conduction and as food storage areas. They are most visible in a cross-sectional view of the tree trunk.

Monoecious

Means having unisexual flowers with staminate (male) and pistillate (female) flowers borne on the same tree, though often on different branches.

N

Native tree

Inherent and original to a geographic area.

Naturalized

This means nonnative trees that have escaped cultivation and are growing in the wild.

Needle-like leaves

These are very thin, sharp, pointed, pin-like leaves; found on pines, firs and some other softwoods.

Node

Means the point on a stem at which leaves and buds are attached.

Nut

The hard, dry fruit with an outer husk that sometimes does not split open readily and an inner shell that is papery to woody.

O

Opposite

Two or three leaves that are directly across from each other on the same twig.

Outer bark

The area of the tree trunk composed of dead cells. It insulates and protects inner tissues from disease infections and drying.

P

Palmate

Blades or lobes or veins of the leaf arranged like fingers on the palm of a hand.

Persistent

Deciduous leaf blades that remain on the tree for more than a year.

Petiole

The leafstalk that connects the blade(s) to the twig.

pH

Acidity or alkalinity ranging from 3 (strongly acid) to 11 (strongly alkaline) with 7 being neutral.

Photosynthesis

This is the process that occurs in the leaves. From energy produced by sunlight, the leaves combine carbon dioxide from the air and water from the soil to produce carbohydrates. Oxygen is released in the process. Carbohydrates plus fats and proteins are the plant foods necessary for growth and respiration of the tree.

Phytoremediation

The use of trees to take up chemicals, binding some of the material in an inert form with the tree, and converting some of it to other substances—possibly even breaking it down into the normal end product of a tree’s chemical processes.

Pinnate

Blades of lobes or veins of the leaf arranged like vanes of a feather.

Pistil

The seed-bearing organ of the flower. The pistil consists of an ovary, stigma and style when present.

Pollination

To transfer pollen from the anther of a stamen to the stigma of a pistil, resulting in fertilization. This can occur either on a single plant (self-pollination) or between different plants. Insect pollination and wind pollination are two examples of natural pollination.

Polygamous

Having some unisexual flowers and some bisexual flowers on each plant (can be polygamo-monoecious or polygamo-dioecious).

Pome

This is a fruit with a fleshy outer coat and a stony layer (similar to plastic) within, with seeds inside the stony layer (apples, pears, etc.).

Pubescent

Means covered with hairs.

R

Reforestation

The planting of forested land that has been lost due to fire, logging, drought, pests or disease to restore beauty to the landscape, provide food and habitat for wildlife and allow recreational activities.

Riparian Zone

An area of ecological transition between the aquatic zone and the upland zone (e.g., the bank of a river).

Roots

Root hairs absorb water and mineral salts from the soil. Larger roots anchor the tree and store nitrogen and carbohydrates.

Rootstock

The root upon which the scion is grafted.

S

Samara

Winged fruit.

Sapwood

The area on the outer side of the trunk, which contains the sap conducting tubes. Sapwood is usually lighter in color, but it darkens with age and becomes heartwood. Heartwood and sapwood together comprise the xylem.

Scion

The part of the tree that is grafted or budded to rootstock.

Seed

That part of the fruit capable of germinating and producing a new plant.

Self-fertile

Fertile by means of its own pollen. This makes it theoretically possible for both pollen and ovules to unite (with the help of pollinators such as bees) and produce fruit without a second tree being present.

Self-pollinating

A self-fertile specimen that does not require pollinators (such as bees) to unite the pollen and ovules.

Simple leaf

A single leaf blade with a bud at the base of the leaf stem.

Sinus

Indentation between lobes on a leaf.

Softwood

Term used to describe all needle-leaved trees. These species are typically evergreen, retaining their leaves through two or more growing seasons. Larches, including tamarack, are exceptions, being deciduous “softwoods”

Specimen Tree

A tree placed so people can gain the greatest enjoyment for the color, texture, scent or other pleasures it provides.

Spurs

Stubby, often sharp twigs.

Scale-like leaves

These are small, short, fish-scale-like leaves which cover the entire twig; found on juniper and redcedar.

Scientific names

The Latin-based names used world-wide to standardize names of trees and other plants and animals.

Semi-ring-porous

This is a type of hardwood in which the vessels in the spring-wood are somewhat larger than vessels in summer-wood; between diffuse-porous and ring-porous (black cherry, black walnut, etc.).

Serrate

Means with teeth.

Shade intolerant

Those trees that need a lot of sunlight for growth and survival.

Shade tolerant

Those trees that can tolerate less sunlight for growth and survival.

Shrub

These are low-growing woody plants with many stems rather than one trunk.

Species

These are trees with similar characteristics and that are closely related to each other; species is used in both the singular and plural sense (specie is not proper).

Spring-wood

The wood on the inside of an annual ring, formed during the spring; cells are often thinner-walled.

Stamen

Means the pollen-bearing (male) organ of a flower.

Staminate flower

This is a unisexual (male) flower-bearing only stamens.

Strobile

A cone or inflorescence with overlapping bracts or scales.

Summer-wood

Wood on the outside of an annual ring, formed during the summer; this wood is sometimes dark and cells are often thicker-walled.

T

Toothed

Notches on the outer edge of a leaf.

Tree

A woodyplant, generally single-stemmed, that reaches a height of more 15 feet at maturity. A tree has three major parts: roots, trunk and the crown.

Trunk

The main body of the tree.

Triploid

Having three sets of chromosomes rather than the usual two. As a result, the pollen is sterile.

X

Xeriscape

Saving water while maintaining trees and other plants in the landscape.

Xylem

This is plant vascular tissue that conveys water and dissolved minerals from the roots to the rest of the plant and also provides physical support.