Lamina

Lamina (Plural: Laminae ) [ Botany ]
Synonym: Leaf blade
Adjective: Laminar

Dictionary of botanic terminology - index of names


	A thin, flat, blade-like organ, part or expansion. (e.g. the blade of a leaf or petal)

[ From Latin. "lamina" a blade or a thin plate ] Any thin, flat layer or sheet of membrane or other tissue. It may be a part of a larger structure.

Lamina of the leaf (Blade) [ Botany]

The lamina is the expanded portion or blade of a leaf and it is an above-ground organ specialized for photosynthesis. For this purpose, a leaf is typically, to a greater or lesser degree, flat and thin, to expose the chloroplast containing cells (chlorenchyma) to light over a broad area, and to allow light to penetrate fully into the tissues.

Lamina parts:

Leaf apex: The tip of a leaf opposite to the petiole.
Margins: The boundary area extending along the edge of the leaf.
Lobes: A partial rounded portion of a le af margin, separated from the whole by a more or less deeply indentation (sinus)
Vein: A vascular bundle (the ribs) at or near the surface that provides supports for the leaf and transports both water and food.

The Adaxial or ventral surface: is the upper surface of a leaf lamina facing toward the stem.
The Abaxial or dorsal surface: of a leaf lamina is the underside or side facing away from the stem.

The shape or form of the leaf lamina is an important characteristic used for leaf classification. See: leaf shape

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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