plants

Biodiversity

The variety of life in the world or in a particular habitat or ecosystem.

Monocot

A type of flowering plant that has one cotyledon in its seed.

Dicot

A type of flowering plant that has two cotyledons in its seed.

Transpiration

The process of water movement through a plant and its evaporation from aerial parts.

Phloem

The vascular tissue in plants responsible for the transport of nutrients and the products of photosynthesis.

Xylem

The vascular tissue responsible for the conduction of water and dissolved minerals upward from the roots.

Vascular Plants

Plants that have specialized tissues (xylem and phloem) for the transport of water and nutrients.

Meristem

Tissue in plants consisting of undifferentiated cells capable of division and growth; includes apical, lateral, and root meristems.

Cotyledon

The first leaf or leaves that appear from a germinating seed.

Tropism

A growth response of a plant toward or away from a stimulus; includes phototropism, gravitropism, and thigmotropism.

Angiosperm

A group of flowering plants that produce seeds enclosed within a fruit.

Gymnosperm

A group of plants that produce seeds that are not enclosed in an ovary (fruit); typically cone-bearing.

Herbaceous

Plants that have soft, non-woody stems.

Tracheid

A type of water-conducting cell in the xylem of vascular plants.

Vessel Element

A type of water-conducting cell in the xylem that is wider and more efficient than tracheids.

Sieve Tube

The part of the phloem that transports sugars and other metabolic products downward.

Companion Cell

A specialized parenchyma cell that assists with the transport of sugars through the phloem.

Stomata

Small openings on the surface of leaves that allow gas exchange to occur.

Guard Cell

Cells that surround stomata and control their opening and closing.

Plant Hormones

Chemical messengers in plants that regulate growth and responses to environmental stimuli; includes auxins, gibberellins, cytokinins, ethylene, and abscisic acid.

Vascular Cambium

A layer of tissue in plants that produces new phloem and xylem.

Endodermis

The inner layer of the cortex in plant roots, surrounding the vascular tissue.

Vascular Bundle

The part of the plant that contains xylem and phloem tissues.

Positive Tropism

A growth response of a plant toward a stimulus.

Negative Tropism

A growth response of a plant away from a stimulus.

Osmosis

The movement of water through a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.