A model of flower formation identifying three classes of organ identity genes that direct formation of the four types of floral organs.
A flowering plant that completes its entire life cycle in a single year or growing season
A bud at the tip of a plant stem; also called a terminal bud
Concentration of growth at the tip of a plant shoot, where a terminal bud partially inhibits axillary bud growth
Embryonic plant tissue in the tips of roots and the buds of shoots. The dividing cells of an apical meristem enable the plant to grow in length
A structure that has the potential to form a lateral shoot, or branch. The bud appears in the angle formed between a leaf and a stem
All tissues external to the vascular cambium, consisting mainly of the secondary phloem and layers of periderm.
flowering plant that requires two years to complete its life cycle
The flattened portion of a typical leaf
A flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining growth.
A type of plant cell that is connected to a sieve-tube element by many plasmodesmata and whose nucleus and ribosomes may serve one or more adjacent sieve-tube elements.
A cylinder of meristematic tissue in woody plants that replaces the epidermis with thicker, tougher cork cells.
In plants, ground tissue that is between the vascular tissue and dermal tissue in a root or eudicot stem.
A tough coat that covers the body of a nematode.
The outer protective covering of plants
Dermal tissue system
A type of growth characteristic of most animals and some plant organs, in which growth stops after a certain size is reached.
The innermost layer of the cortex in plant roots; a cylinder one cell thick that forms the boundary between the cortex and the vascular cylinder.
The dermal tissue system of nonwoody plants, usually consisting of a single layer of tightly packed cells
A lignified cell type that reinforces the xylem of angiosperms and functions in mechanical support; a slender, tapered sclerenchyma cell that usually occurs in bundles.
Plant tissues that are neither vascular nor dermal, fulfilling a variety of functions, such as storage, photosynthesis, and support
Ground tissue system
The two cells that flank the stomatal pore and regulate the opening and closing of the pore.
A type of growth characteristic of plants, in which the organism continues to grow as long as it lives
A segment of a plant stem between the points where leaves are attached
A meristem that thickens the roots and shoots of woody plants. The vascular cambium and cork cambium are lateral meristems
A root that arises from the pericycle of an established root.
The main photosynthetic organ of vascular plants.
A finger-like projection along the flank of a shoot apical meristem, from which a leaf arises
A small raised area in the bark of stems and roots that enables gas exchange between living cells and the outside air.
Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth
A plant gene that promotes the switch from vegetative growth to flowering
Meristem identity gene
The ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis
An organism’s external form.
A point along the stem of a plant at which leaves are attached.
A specialized center of body function composed of several different types of tissues.
A plant homeotic gene that uses positional information to determine which emerging leaves develop into which types of floral organs.
Organ identity genes
A relatively unspecialized plant cell type that carries out most of the metabolism, synthesizes and stores organic products, and develops into a more differentiated cell type.
The development of a multicellular organism’s spatial organization, the arrangement of organs and tissues in their characteristic places in three-dimensional space.
A flowering plant that lives for many years
The outermost layer in the vascular cylinder from which lateral roots arise.
The protective coat that replaces the epidermis in woody plants during secondary growth, formed of the cork and cork cambium.
The stalk of a leaf, which joins the leaf to a node of the stem.
A shift from one developmental phase to another
Vascular plant tissue consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plant
Ground tissue that is internal to the vascular tissue in a stem; in many monocot roots, parenchyma cells that form the central core of the vascular cylinder.
A lack of symmetry; structural differences in opposite ends of an organism or structure, such as the root end and shoot end of a plant.
Molecular cues that control pattern formation in an animal or plant embryonic structure by indicating a cell’s location relative to the organism’s body axes. These cues elicit a response by genes that regulate development.
Microtubules in the cortex (outer cytoplasm) of a cell that are concentrated into a ring.
Growth produced by apical meristems, lengthening stems and roots.
The tissues produced by apical meristems, which lengthen stems and roots.
Primary plant body
An organ in vascular plants that anchors the plant and enables it to absorb water and minerals from the soil.
All of a plant’s roots, which anchor it in the soil, absorb and transport minerals and water, and store food.
A tiny extension of a root epidermal cell, growing just behind the root tip and increasing surface area for absorption of water and minerals.
A short, irregular sclerenchyma cell in nutshells and seed coats. Sclereids are scattered throughout the parenchyma of some plants.
A rigid, supportive plant cell type usually lacking a protoplast and possessing thick secondary walls strengthened by lignin at maturity.
Growth produced by lateral meristems, thickening the roots and shoots of woody plants.
The tissues produced by the vascular cambium and cork cambium, which thicken the stems and roots of woody plants.
Secondary plant body
The aerial portion of a plant body, consisting of stems, leaves, and (in angiosperms) flowers.
A living cell that conducts sugars and other organic nutrients in the phloem of angiosperms; also called a sieve-tube member. Connected end to end, they form sieve tubes.
Sieve tube element
The vascular tissue of a stem or root.
A vascular plant organ consisting of an alternating system of nodes and internodes that support the leaves and reproductive structures.
A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant.
A main vertical root that develops from an embryonic root and gives rise to lateral (branch) roots
An integrated group of cells with a common function, structure, or both.
One or more tissues organized into a functional unit connecting the organs of a plant.
A long, tapered water-conducting cell found in the xylem of nearly all vascular plants. Functioning tracheids are no longer living
A cylinder of meristematic tissue in woody plants that adds layers of secondary vascular tissue called secondary xylem (wood) and secondary phloem.
A transport system formed by xylem and phloem throughout a vascular plant. Xylem transports water and minerals; phloem transports sugars, the products of photosynthesis.
Vascular tissue system
In plants, a vascular bundle in a leaf.
A short, wide water-conducting cell found in the xylem of most angiosperms and a few nonflowering vascular plants. Dead at maturity, vessel elements are aligned end to end to form micropipes called vessels.
A continuous water-conducting micropipe found in most angiosperms and a few nonflowering vascular plants.
Vascular plant tissue consisting mainly of tubular dead cells that conduct most of the water and minerals upward from the roots to the rest of the plant