Nurse plant

Nurse plant association [ Ecology ]

Dictionary of botanic terminology - index of names

A nurse plant is a plant that creates an environment that is more favourable for young seedlings to grow underneath it to survive in a harsh desert environment

Nurse plant association is a phenomenon that occurs mostly only in desert environments. A nurse plant is a plant that creates an environment that is less severe for young seedlings growing underneath it to survive in a harsh desert environment. The importance of nurse plant associations ranges from providing shade to providing the only means of seedling establishment.
*Seedlings of Pelecyphora aselliformis at the base of the mother plant.*	The seedlings of many succulent plants are found only in sheltered microhabitats, nearly all occurring under the canopy of a desert grass, shrub or under the mother plant its self. Seedlings were generally located near the base or on the northern side of the nurse plant this because the soil surface temperatures can reach 71°C in exposed areas. A seedling is vulnerable to desiccation when fully exposed to the heat of the desert sun, but when growing in the shade of a larger plant, has more of a chance of survival. The larger plant also protects seeds from predation from birds and rodents, allowing them a chance to germinate. Seedlings in harsh environments are often more dependent on a nurse relationship than seedlings in more benign environments
In other environments, growing under the shade of a larger plant may be detrimental to a seedling's growth, reducing the amount of sunlight available for photosynthesis, but the harsh desert environment makes this protection more beneficial. Thus, although the nurse plant facilitates seedling establishment by reducing maximum soil surface temperatures and provides a microhabitats with higher soil nitrogen levels, its shading and competition for water reduce seedling growth. Addition to benefits provided by a nurse, seedling performance in unfavorable environmental conditions can be aided by mycorrhizal relationships.

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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