Glossary: A

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abaxial

On the side away from the axis, usually refers to the underside of a leaf relative to the stem.

abscission

Shedding branches, leaves, or flowers at a seam; usually seasonally (i.e., leaves abscise in the Fall in New England).

acaulescent

With lower leaves reduced to sheaths or scales so that leaves/flowers appear to arise directly from rootstock.

acaulous

Without a stem.

achene

A dry, usually 1-seeded fruit that does not separate or split open at maturity.

achlorophyllous

Lacking chlorophyll and therefore incapable of photosynthesis.

acropetal

In the direction of the tip or apex.

acroscopic

In the direction of the tip or apex.

actinomorphic

Radially symmetrical; a shape that can be divided by 2 or more planes into roughly equal halves, usually refers to the perianth of a flower.

acuminate

Tapering to a narrow point, more tapering than acute, less than attenuate.

acute

Condition of an apex with more or less straight sides that meet to form an angle of less than 90°, more pointed than obtuse, but less pointed than acuminate.

adaxial

On the side toward the axis, usually refers to the top side of a leaf relative to the stem.

adnate

An organ that is fused with a structure different from itself, as when stamens are attached to petals.

adpressed

Lying close and flat, usually referring to leaves growing up against the stem.

adventitious

A structure such as a bud or root that is produced on an unusual part of the plant (i.e., roots that come from stems).

adventive

A species not intentionally introduced; growing here and there.

aerenchyma

Plant tissue that is filled with large air spaces, usually in the stem or rhizome/root.

aerial

Above-ground.

aerial leaves

On aquatic plants, the leaves that are produced above the water's surface.

aggregate fruit

A fruit such as a raspberry that is actually composed of multiple, fused fruits (small drupes).

Agrotis ipsilon

Black Cutworm, photo ©Adam Sisson, Iowa State University, Bugwood.org.

Allagrapha aerea

Unspotted Looper Moth, photo ©Carol Wolf, North American Moth Photographers Group.

allopatric

Species that do not occur in the same geographic ranges.

alternate

A node bears only 1 similar organ, such as a leaf or flower (compare with opposite, whorled).

alveolate

With many angular cavities, like a honeycomb.

ament

Catkin: a slender, usually pendulous inflorescence, with crowded male or female flowers.

amphibious

Plants adapted to living in water or on land.

amphistomic

With stomata on both leaf surfaces.

ampliate

Epanding or enlarged.

Anageshna primordialis

Yellow-spotted Webworm Moth, photo ©Carol Wolf, North American Moth Photographers Group.

Anagrapha falcifera

Celery Looper, photo ©Robert J. Bauernfeind, Kansas State University, Bugwood.org.

Andrena barbilabris

Long-lipped Mining Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

Andrena ceanothi

Mining Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

Andrena miranda

Mining Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

Andrena nasonii

Nason's Mining Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

Andrena ziziae

Golden-Alexanders Andrena, photo ©Brooke Alexander, USGS Native Bee Inventory and Monitoring Laboratory.

androecium

The collective term for the male organs (stamens) of the flower.

androgynous

With both male and female flowers in the same inflorescence.

anemophilous

Wind-pollinated.

angiosperm

Flowering plants that bear seeds that are enclosed in an ovary.

angular

With edges where two planes meet (come together at an angle). Opposite: "rounded".

anisophyllous

With two opposite leaves of very different sizes at the same node.

annual

A plant that lives for only one year.

annual growth constrictions

In Lycophytes, areas of the stem with smaller leaves that are produced at the colder beginning and end of the growing season.

annular

Like a ring, or with organs arranged in a ring.

annulus

Ring of specialized cells encircling a fern sporangium.

antepetalous

When the stamens are positioned opposite the petals in a flower.

anterior

Positioned in front of.

antesepalous

When the stamens are positioned opposite the sepals in a flower.

anther

The pollen-bearing structure in a flower, usually borne at the end of a stalk called a filament.

antherode

A sterile, modified anther.

Anthidiellum notatum

Leaf-cutting Bee, photo ©Joyce Amihere, USGS Native Bee Inventory and Monitoring Laboratory.

anthocyanic

Tinged or colored with a pink, red, or purple pigment.

anthocyanin

A purplish-red, usually protective pigment.

Anthophora abrupta

Chimney Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

Anthophora terminalis

Orange-tail Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

anthropogenic

Caused, introduced by, or resulting from human activity; a disturbed or man-made habitat.

Anticarsia gemmatalis

Velvetbean Caterpillar Moth, photo ©Jim Vargo, North American Moth Photographers Group.

antrorse

Pointing upward or forward toward the distal end.

apetalous

With no petals.

apex (plural: apices)

Tip or top.

aphyllopodic

With basal leaves much reduced or absent.

apiculate

With an abrupt, short, projected tip.

apiculus

A short projected tip.

Apis mellifera

European Honey Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

aplexicaulous

Clasping, as with a leaf with two bases that wrap around the stem.

apomictic

The production of seeds without fertilization.

apomixis

The production of seeds without fertilization.

apophysis

The outer part of a cone scale that is exposed even when the cone is closed.

apparently secure

Uncommon but not rare; some cause for concern due to declines or other factors.

appendage

A secondary projection, ear, or other piece of tissue attached to a main structure.

appressed

Lying close and flat, usually referring to leaves growing up against the stem.

aquatic

Living in water.

arcuate

Arching, as in curving veins in a leaf blade.

areole

A bounded space, as with leaves with net-like venation.

aril

An appendage of a seed, usually brightly colored, fleshy, and/or sweet, that attracts animals to eat it and coincidentally disperse the seed.

aristate

Tipped with a long, slender bristle.

armature

Protective sharp projections like bristles, barbs, or thorns.

armed

Bearing a sharp projection such as a prickle, spine, or thorn.

articulated

One structure joined to another, usually at a point where the two will separate.

ascending

Diverging from an axis at an angle of 15–45°, less upward than erect, less outward than spreading.

asexual

Without male or female organs; reproducing vegetatively, without fertilization by another plant.

asymmetrical

With unequally sized or shaped parts on either side of a central axis.

attenuate

Tapering very gradually to a prolonged tip or base.

Augochlora pura

Golden Green Sweat Bee, photo ©Phillip Moore, USGS Native Bee Inventory and Monitoring Laboratory.

Augochlorella aurata

Blue-green Sweat Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

Augochloropsis sumptuosa

Blue Sweat Bee, photo USGS Native Bee Inventory and Monitoring Laboratory.

auricle

Ear-like lobe (usually refers to a leaf base).

authority

The botanist who first officially named a taxon.

Autographa ampla

Large Looper Moth, photo ©Jim Vargo, North American Moth Photographers Group.

Autographa precationis

Common Looper Moth, photo ©David Cappaert, Bugwood.org.

autotroph

A plant that makes its own food from raw materials obtained from the sun, water, and soil.

avleolus

Depressions or cavities in a surface.

awn

Fine bristle (usually referring to scales of Carex or bracts of grass flowers).

axil

The juncture where a lateral organ, such as a leaf, joins a main axis, like a stem.

axillary flower

A flower that emerges from an axil (i.e. the juncture between a branch or leaf and the stem).

axis

The main stem of a structure, such as a plant or inflorescence.