Choose from the categories below to help define a term:

General Leaves
Flowers Fruits

 

General

Woody: With hard (lignified) tissues that will retain their shape long after death.

Herbaceous:  With soft tissues that collapse soon after death.

Perennial:  Living more than two years.

Biennial:  Normally living two years.

Annual:  Normally living only one year. Winter annuals germinate in the autumn and mature and die the next spring or summer.

Tendril:  An elongated twining segment of a leaf or branch, usually supporting the stem.

Lenticel:  A portion of the cork layer in the bark of stems where the cells are loose, allowing exchange of gases. Usually they are raised and they may be a different color from the rest of the bark.

Rhizome:  A horizontal underground stem. Rhizomes produce stems above ground at intervals, as in sod-forming grasses, bracken fern, and others.

Stolon or Runner:  Similar to a rhizome (being a stem), but located on or near the soil surface.

back to top

 

 

Leaves

A leaf has a bud in its axil (at the angle between the leaf-stalk and the stem), whereas a leaflet has no bud at its base. This is a way to distinguish a leaf from a leaflet.
 
Simple Leaf:  A leaf in which the blade is all one unit.

Compound Leaf:  A leaf in which the blade is composed of separate parts, each part called a leaflet. Decompound means more than once compound.

Alternate:  Only one leaf arising at a node.

Opposite:  Two leaves arising at a node.

Whorled:  More than two leaves arising at a node.

Sessile:  Without a petiole or leaf-stalk, that is, the blade is attached directly to the stem.  The contrasting condition is petiolate.
 
Pinnate:  Arranged like a feather, with the parts arising along a central axis.

Palmate:  Arranged like the fingers arising from the palm of the hand, with the several parts all attached to one point.

Glabrous:  Without hairs on the surface.

Pubescent:  With hairs. There are various kinds of pubescence, differing in the stiffness, length, and density of the hairs (villous, hirsute, hispid, tomentose, etc.)

Stipule:  One of a pair of appendages sometimes present at the base of a leaf-stalk.  (Petiole).
 
 
Cauline: Of or pertaining to the stem. Cauline leaves are those borne on the stems above the soil surface.

Basal: Arising from the stem at or below the ground surface only.

back to top

 

 

Flowers

Pistil:  The ovule-bearing or seed-bearing organ of a flower, consisting, when complete, of ovary, style and stigma.

Stamen:  The pollen-bearing organ of a flower, of a flower, consisting of the filament and the anther.

Ovary:  The enlarged lower part of the pistil, enclosing the ovules or young seeds.

Style:  A narrow, usually of cylindrical and more or less filiform extension of the ovary, which, when present, bears the stigma at its apex.

Stigma:  That part of a pistil which receives the pollen.

Anther:  The pollen-bearing part of a stamen.

Carpel:  A simple pistil or a single member of a compound pistil; regarded as a modified leaf.

Bisexual or Perfect:  With both stamens and pistils.
Unisexual:  With either stamens (staminate flower) or pistils (pistillate flower), but not both.

Monoecious Plant:  Flowers unisexual but with both kinds of flowers on one individual plant.

Dioecious Plant:  Flowers unisexual but with only one sex per individual plant.

Bract:  A reduced (smaller than normal sized) leaf at the base of a flower-stalk. If the flower-stalk is short or absent the bract or bracts may be at the base of a flower and resemble sepals.

Panicle:  Loose, diversely branching flower cluster.

back to top

 

 

Fruits

Berry:  A fleshy fruit having numerous seeds embedded in the flesh (tomato, Solanum, Phytolacca).

Capsule:  A dry, many-seeded fruit derived from more than one carpel, splitting open at maturity. Capsules often have several chambers (Ricinus, Agrostemma).

Follicle:  A dry fruit derived from only one carpel which splits open on one side at maturity. Follicles have one chamber and many seeds (Asclepias, Apocynum).

Legume or Pod:  The fruit of members of the family Leguminosae. One chambered, normally splitting on both edges, enclosing a row of seeds (garden peas and beans, Cassia, Robinia).

back to top

 


Copyright © 2002
University of Pennsylvania
Created by:   Alexander Chan (2003), Daphne Downs (2002), Chris Tsai (2001), Brett Begley (2000), Janet Triplett (1997)
Faculty Advisor:  Dr. Robert Poppenga