Glossary of plant morphology

Glossary of Plant Morphology

This article provides a glossary of terms used in plant morphology, the study of the physical form and external structure of plants. This includes terminology related to the anatomy and physiology of plants, as well as their taxonomy and classification.

A

Apical dominance: The phenomenon whereby the main, central stem of the plant is dominant over (i.e., grows more strongly than) other side stems.

Axil: The angle between the upper side of a leaf or stem and the supporting stem or branch.

B

Bark: The protective outer layer of the stems and roots of woody plants.

Bud: An undeveloped or embryonic shoot, often covered by scales.

C

Cambium: A layer of tissue between the wood and the bark, from which new bark or wood cells originate.

Cotyledon: A significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling.

D

Dormancy: A period in an organism's life cycle when growth, development, and physical activity are temporarily stopped.

Drupe: A type of fruit in which an outer fleshy part surrounds a shell with a seed inside.

E

Epidermis: The outermost layer of cells covering the plant.

Evergreen: A plant that has leaves in all seasons.

F

Flower: The reproductive structure found in flowering plants.

Fruit: The mature ovary of a flowering plant, usually containing seeds.

G

Germination: The process by which a plant grows from a seed.

Grafting: A horticultural technique whereby tissues of plants are joined so as to continue their growth together.

H

Herbaceous: Describes plants that have non-woody stems.

Hybrid: The offspring resulting from combining the qualities of two organisms of different breeds, varieties, species, or genera through sexual reproduction.

I

Inflorescence: A group or cluster of flowers arranged on a stem.

Internode: The portion of a plant stem between two nodes.

J

Juvenile: An individual organism that has not yet reached its adult form, sexual maturity, or size.

K

Karyotype: The number and visual appearance of the chromosomes in the cell nuclei of an organism or species.

Kingdom: The second highest taxonomic rank, below domain.

L

Leaf: The main organ of photosynthesis and transpiration in higher plants.

Lignin: A complex organic polymer deposited in the cell walls of many plants, making them rigid and woody.

M

Meristem: Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth.

Monocotyledon: Plants having one embryonic seed leaf or cotyledon.

N

Node: A point of attachment of a leaf or a twig on the stem in seed plants.

Nucleus: A membrane-bound organelle that contains the cell's chromosomes.

O

Organ: A part of an organism that is typically self-contained and has a specific vital function.

Ovary: The part of a flower that develops into a fruit.

P

Petal: One of the often brightly colored parts of a flower immediately surrounding the reproductive organs.

Photosynthesis: The process by which green plants and some other organisms use sunlight to synthesize foods with the aid of chlorophyll pigments.

Q

Quiescence: A state of quietness or inactivity in a seed that is not germinating but can under proper conditions.

R

Root: The part of a plant that typically lies below the surface of the soil.

Rhizome: A continuously growing horizontal underground stem that puts out lateral shoots and adventitious roots at intervals.

S

Seed: An embryonic plant enclosed in a protective outer covering.

Stem: The main structural axis of a plant.

T

Tissue: An ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function.

Transpiration: The process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers.

U

Umbel: An inflorescence that consists of a number of short flower stalks which spread from a common point.

V

Vascular tissue: The complex conducting tissue, formed of more than one cell type, found in vascular plants.

Vegetative reproduction: Any form of asexual reproduction occurring in plants.

W

Water potential: The potential energy of water per unit volume relative to pure water in reference conditions.

Wood: The hard fibrous material that forms the main substance of the trunk or branches of a tree or shrub.

X

Xylem: One of the two types of transport tissue in vascular plants, phloem being the other.

Y

Yield: The amount of a crop that is harvested per unit of land area.

Z

Zone of elongation: The region of the root where cells are actively elongating but are no longer dividing.

Zone of maturation: The region of the root where the cells differentiate into various types of cells.

See also

• Glossary of botanical terms
• Glossary of leaf morphology
• Glossary of stem morphology
• Glossary of root morphology