| A | B |
|---|
| growth | the irreversible increase in mass that results from cell division and cell expansion |
| development | the sum of all of the changes that progressively elaborate an organism's body |
| annuals | plants that complete their life cycle in a single year or less |
| biennial | a plant whose life cycle generally spans two years |
| perennials | plants that live many years |
| meristems | embryonic tissues perpetually found in regions of growth |
| apical meristems | supply cells for the plant to grow in length |
| primary growth | the elongation of plants enabled by apical meristems |
| secondary growth | a progressive thickening of the roots and shoots formed earlier by primary growth |
| lateral meristems | cylinders of dividing cells extending along the length of roots and shoots |
| primary plant body | the parts of the root and shoot systems produced by apical meristems |
| root cap | physically protects the delicate meristem as the root pushes through the abrasive soil during primary growth |
| zone of cell division | includes the apical meristem and the primary meristems |
| quiescent center | a population of cells that divide much more slowly than the other meristematic cells |
| protoderm | the outermost primary meristem, which gives rise to the epidermis of roots and shoots |
| procambium | a primary meristem of roots and shoots that forms the vascular tissue |
| ground meristem | a primary meristem that gives rise to ground tissue in plants |
| zone of elongation | the place where cells elongate, sometimes to more than ten times their origional length |
| zone of maturation | the place where the cells of the root begin to specialize in structure and function |
| stele | a central cylinder of vascular tissue where both xylem and phloem develop |
| endodermis | the innermost layer of the cortex; a cylinder one cell thick that forms the boundary between the cortex and the stele in the roots of both monocots and dicots |
| pericycle | the outermost layer of the stele |
| vascular bundles | strands of vascular tissue that run the length of the stem |
| stomata | tiny pores that allow gas exchange between the surrounding air and the photosynthetic cells inside the leaf |
| guard cells | specialized epidermal cells |
| mesophyll | the ground tissue of a leaf between the upper and lower epidermis |
| secondary plant body | consists of tissues produced during this secondary growth in diameter |
