Perianth

Perianth [ Botany ]

Dictionary of botanic terminology - index of names


	The perianth is the combined structure of the flower comprising the calyx (sepals) and corolla (petals) considered collectively as a floral cup; otherwise when the individual segments are similar they are called tepals.

[from the Latin and Greek words for "around" and "flower"] It surrounds the pistil and stamens. The perianth segments and stamen (s) may be attached to the pistil(s) in one of three ways: Hypogynous positioned below the pistil Perigynous positioned around the pistil Epigynous positioned above the pistil In Cactaceae, the perianth form an intergrading series of segment variously known as, tepals, sepaloids and petaloids.

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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