Arboretum of Eden

Welcome to the College of the Atlantic Arboretum


Feeling lost when reading botanical descriptions? No worries! Look up new terms in the glossary:

Abaxial Lower surface.

Adaxial Upper surface.

Alternate [Arrangement of leaves or buds] Not opposite on sides of twig.

Awl-shaped [Leaf] Narrow and tapering to a sharp point.

Bisexual [Flower] Each flower has both male and female structures. They are also called perfect flowers.

Bole The main stem of a tree; usually the part that is commercially useful for lumber or other wood products.

Bract A leaf-like structure which is attached to a flower, a fruit or to its stalk.

Branchlet Shoot growth of the latest growing season.

Bur [Fruit] A prickly or spiny husk enclosing the seed.

Capsule [Fruit] A dry fruit enclosing more than one seed and splitting freely at maturity.

Catkin A compact, cylindrical cluster of flowers of the same sex.

Chambered [Pith] With hollow cavities separated by discs or plates.

Compound [Leaf] A leaf composed of smaller leaf units or leaflets.

Conical Wide at the base and gradually tapering to a point.

Conifer Cone-bearing trees; the “evergreens.”

Cordate Heart-shaped at the petiole end or base.

Corymb [Flower] A flat-topped floral cluster with outer flowers opening first.

Cyme [Flower] A flattened flowering structure, center flowers bloom earliest.

Deciduous [Leaves] All leaves drop in the autumn.

Diaphragmed [Pith] Solid but divided into sections by firmer discs.

Dioecious The plant has either only male or only female flowers. Word originates in Greek, meaning “two households.”

Drupe [Fruit] Fleshy outside, hard and stone-like inside; for example peach, mango, cherries.

Entire [Leaf] Margin of leaf without teeth, lobes, or divisions.

Fascicle [Leaf] A cluster of conifer leaves.

Glabrous Smooth, without hairs.

Glands Generally raised structures at the tips of hairs, or on a leaf, petiole, or twig.

Habitat The place where a plant usually grows.

Hardwood Term used to describe all broad-leaved trees, typically deciduous. Despite the term, some “hardwoods” have relatively soft wood, such as aspens.

Husk [Fruit] The somewhat leathery, outer covering of a fruit.

Imperfect [Flower] Flower is lacking some reproductive parts, such as stamens.

Invasive Not native to and tending to spread in a habitat or environment, sometimes displacing native species.

Leaf Stalk (petiole) and blade of hardwoods; needle-like and scales of conifers.

Leaflets Smaller leaf units which together form a compound leaf.

Lenticel [Bark] Raised pores on woody parts with openings for air-gas exchange.

Lobed [Leaf] With large, rounded or pointed projections along the leaf margin. Projections formed by indentations of the leaf margin.

Margin [Leaf] The edge forming the outline.

Midrib [Leaf] The large central vein.

Monoecious Flowers of both sexes appear on one plant (either unisexual or bisexual flowers). Word originates in Greek, meaning “one household.”

Opposite [Arrangement of leaves or buds] Directly across from one another on a common axis, or twig.

Panicle [Flower] A loosely branched, pyramidal cluster of flowers.

Petiole [Leaf] The stalk that supports the leaf blade.

Pith The central, soft part of the stem.

Prickle Extension of cortex and epidermis; for example Rose prickles.

Pubescent Covered with hairs.

Rachis The common stalk in a compound leaf to which the leaflets are attached.

Samara [Fruit] A dry, winged fruit; for example Maple fruit.

Scales [Bud] Small, modified leaves on the outer surface of buds.

Scales [Cone] The basic structures that enclose the seeds.

Scale-like [Leaf] Small, generally overlapping, triangular-shaped leaves of some conifers; for example Cedar or Juniper.

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

Sessile Attached directly by the base without an intervening stalk.

Shrub A woody, many-stemmed plant, usually under 15 feet (4.5 m) in height at maturity, which branches from its base.

Simple [Leaf] A single leaf composed of a single blade.

Softwood Term used to describe all needle-leaved trees, typically evergreen. Larches are exceptions, being deciduous “softwoods.”

Solid [Pith] Without cavities or sections separated by discs.

Spike A flower stalk.

Spines Modified leaves, stipules, or parts of leaves.

Stipule A tiny, leafy, sometimes spiny projection arising at the base of a petiole.

Stomate (plural Stomata) Small pore on a leaf used for gas exchange.

Thorn Modified branches or stems.

Tree A woody plant, generally single-stemmed, that reaches a height of more than 15 feet (4.5 m) at maturity and a diameter of 3 inches (8 cm) or more measured at 4.5 feet (1.5 m) above the ground.

Whorl [Leaves or branches] More than two originating at the same level on a common axis.

Source: The Maine Forest Service. “Forest Trees of Maine” 2008.

Leaf Margins (Photo by Wikimedia Commons)

Leaf Margins (Photo by Wikimedia Commons)

Leaf shapes and arrangements (Photo by Wikimedia Commons)

Leaf shapes and arrangements (Photo by Wikimedia Commons)

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