Fenestrate

Fenestrate or Fenestrated [ Botany ]
Synonym: Windowed
From Latin: Fenestra = Window
Derived form: Fenestration

Dictionary of botanic terminology - index of names

Of leaves, membrane or other structures having openings, perforations or translucent areas.

[From Latin “fenestratus”, past participle of “fenestrare” to furnish with openings and windows.]

For example leaves pierced with small holes or window like openings or with hyaline areas so thinned as to be translucent or transparent.

Fenestra = Window in Latin language.
Fenestration = The area in which the fenestra occurs.

Left: Two fenestrate plants (Haworthia and Lithops) with their translucent tissues.

Fenestrate habit [ Botany - Morphology]

A fenestrate habit is a vegetative features that describe leaf succulents that have evolved special fenestrate leaves that grow below the surface of the soil

Photo 1: windowed reticulated leaves of Haworthia emelyae
v. comptoniana

photo 2: A longitudinal section showing the transparent tissues.

Fenestrate growth habit of some subterranean leaf succulents.

A number of South African succulents like Lithops ssp. and Haworthia ssp. (See: photo 1 and 2 ) to escape the killing heat of the desert grow almost entirely subterranean and have evolved special fenestrate leaves that grow below the surface of the soil; This succulent leaves have a nearly transparent flat apex exposed to the atmosphere and are even at the soil level. This permit the plants to minimize the heating effects of high light intensity and to reduce the drying effects of desert air during prolonged drought. There are no stomata in the windows, so little water is lost, these plants remain subterranean because they have contractile roots which continually pull the plants deeper into the ground as the stem elongates.

The disadvantage, however, is the limited amount of leaf surface area exposed to the sun for photosynthesis to supply food for the plant but the translucent window in the top surface, however, the fenestration allow sunlight to be captured and utilized even when the plant are retracted below the surface of the soil. This is an interesting evolutionary adaptation to overcome this light problem; their leaves are a simple optical system that permits light striking the windows to be diffused onto the green, photosynthesizing surface situated underground. So, with a minimum of exposure to the outside environment, a maximum area of photosynthetic tissue is ensured.

The fenestrate areas are often patterned, irregularly reticulated or potted and looks like stones allowing the plant to camouflage with the soil surface. ( Below some example of fenestration of Lithops )

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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