| A | B |
|---|
| adventitious | Roots extending from stems and leaves above ground. |
| annual | A plant that completes its entire life cycle in a single year or growing season. |
| apical dominance | Concentration of growth at the tip of a plant shoot, where a terminal bud partially inhibits axillary bud growth. |
| apical meristems | Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length. |
| asymmetric cell division | Cell division in which one daughter cell receives more cytoplasm than the other during mitosis. |
| axillary bud | An embryonic shoot present in the angle formed by a leaf and stem. |
| bark | All tissues external to the vascular cambium in a plant growing in thickness, consisting of phloem, phelloderm, cork cambium, and cork. |
| biennial | A plant that requires two years to complete its life cycle. |
| blade | A leaflike structure of a seaweed that provides most of the surface area for photosynthesis. |
| collenchyma cell | A flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining growth. |
| companion cell | A type of plant cell that is connected to a sieve-tube cell by many plasmodesmata and whose nucleus and ribosomes may serve one or more adjacent sieve-tube cells. |
| cork cambium | A cylinder of meristematic tissue in plants that produces cork cells to replace the epidermis during secondary growth. |
| cortex | The region of the root between the stele and epidermis filled with ground tissue |
| cuticle | (1) A waxy covering on the surface of stems and leaves that acts as an adaptation to prevent desiccation in terrestrial plants. (2) The exoskeleton of an arthropod, consisting of layers of protein and chitin that are variously modified for different functions. |
| dermal tissue system | The protective covering of plants; generally a single layer of tightly packed epidermal cells covering young plant organs formed by primary growth. |
| development | The sum of all of the changes that progressively elaborate an organism's body. |
| endodermis | The innermost layer of the cortex in plant roots; a cylinder one cell thick that forms the boundary between the cortex and the stele. |
| epidermis | 1) The dermal tissue system in plants. (2) The outer covering of animals. |
| fiber | 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. |
| fibrous root systems | Root systems common to monocots consisting of a mat of thin roots that spread out below the soil surface. |
| fusiform initials | The cambium cells within the vascular bundles. The name refers to the tapered ends of these elongated cells. |
| ground meristem | A primary meristem that gives rise to ground tissue in plants. |
| guard cell | A specialized epidermal plant cell that forms the boundaries of the stomata. |
| internode | The segment of a plant stem between the points where leaves are attached. |
| lateral meristem | The vascular and cork cambium, a cylinder of dividing cells that runs most of the length of stems and roots and is responsible for secondary growth. |
| lateral roots | Roots that arise from the outermost layer of the pericycle of an established root. |
| meristem identity genes | Plant genes that promote the switch from vegetative growth to flowering. |
| meristem | Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth. |
| mesophyll | The ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis. |
| morphogenesis | The development of body shape and organization during ontogeny. |
| node | A point along the stem of a plant at which leaves are attached. |
| organ identity gene | A plant gene in which a mutation causes a floral organ to develop in the wrong location. |
| parenchyma cell | A relatively unspecialized plant cell type that carries most of the metabolism, synthesizes and stores organic products, and develops into a more differentiated cell type. |
| pattern formation | The ordering of cells into specific three-dimensional structures, an essential part of shaping an organism and its individual parts during development. |
| perennial | A plant that lives for many years |
| pericycle | A layer of cells just inside the endodermis of a root that may become meristematic and begin dividing again. |
| periderm | The protective coat that replaces the epidermis in plants during secondary growth, formed of the cork and cork cambium. |
| petiole | The stalk of a leaf, which joins the leaf to a node of the stem. |
| phase change | A shift from one developmental phase to another. |
| phloem | The portion of the vascular system in plants consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plant. |
