Secondary growth

Secondary growth [ Botany ]

Dictionary of botanic terminology - index of names


	Increase in diameter of the roots and stems of certain plants (notably shrubs and trees) that results from the production of new cells by the cambium.

In gymnosperms and woody dicots the roots and stems continue to increase in diameter (whereas in monocots and most herbaceous dicots growth ceases with the maturation of the primary tissues ) This is called secondary growth and encompasses all lateral growth, a major component of woody plant tissues. It results from the activity of two lateral meristems: 1. Vascular cambium - gives rise to secondary xylem (wood) to the inside and secondary phloem to the outside 2. Cork cambium - gives rise to the periderm (bark) to the outside and phelloderm to the inside which replaces the epidermis, found only in woody plants.

Advertising

Holdfast roots [ Botany ]
Dictionary of botanic terminology - index of names

Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.

Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans), develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994