Leaf window, also known as epidermal window, and fenestration. is a specialized

leaf A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ...

structure consisting of a translucent area through which light can enter the interior surfaces of the leaf where

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...

can occur. The translucent structure may include epidermal tissue, and in some succulent plants it consists of several cell layers of

parenchyma Parenchyma () is the bulk of functional substance in an animal organ or structure such as a tumour. In zoology it is the name for the tissue that fills the interior of flatworms. Etymology The term ''parenchyma'' is New Latin from the word � ...

, which may also function as water-storage tissue. It can appear as a large continuous patch, a variegated or reticulated region, or as numerous small spots. Is found in some

succulent plant In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', me ...

s native to arid climates, allowing much of the plant to remain beneath the soil surface where it is protected from desiccation by winds and heat while optimizing light absorption. Many species featuring leaf windows are native to Southern Africa.

Functions

The primary function of the translucent windows is to increase the absorption of

radiant energy Radiant may refer to: Computers, software, and video games * Radiant (software), a content management system * GtkRadiant, a level editor created by id Software for their games * Radiant AI, a technology developed by Bethesda Softworks for ''Th ...

, and thereby the rate of photosynthesis. Epidermal windows are commonly situated at the apex of leaves, allowing light to be captured and utilized even when the plant is almost entirely below the soil surface, minimizing exposure of leaf surface area to

desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

by intense heat. The windows focus and channel diffused light to the green photosynthesizing surface hidden inside the underground part of the plant. An absence of

stoma In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bo ...

ta in the translucent tissue prevents water loss. It has been found in the

Lithops ''Lithops'' is a genus of succulent plants in the ice plant family, Aizoaceae. Members of the genus are native to southern Africa. The name is derived from the Ancient Greek words () 'stone' and () 'face', referring to the stone-like appearan ...

species of succulents that leaf window size correlates inversely with habitat

solar irradiance Solar irradiance is the power per unit area ( surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre ...

; plants growing in regions of high irradiance and low-rainfall have smaller windows than those growing in cloudy, high-rainfall regions. The carnivorous cobra lily (Darlingtonia californica) uses fenestration to confuse insects and increase the effectiveness of its trap.

Species

Genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

of plants with numerous species having translucent epidermal windows include: *'' Bulbine'' spp. (B. haworthioides, B. mesembryanthemoides, etc.) *'' Conophytum'' spp. *'' Callisia'' spp. ( ''C. navicularis'', etc.) *'' Fenestraria'' spp. *''

Frithia ''Frithia'' is a genus of succulent plants in the family Aizoaceae, indigenous to several small rocky areas in the vicinity of Gauteng Province, South Africa. Description Like several of its close relatives (e.g. ''Fenestraria'') and other plant ...

'' spp. *''

Haworthia ''Haworthia'' is a large genus of small succulent plants endemic to Southern Africa ( Mozambique, Namibia, Lesotho, Eswatini and South Africa). Like the aloes, they are members of the subfamily Asphodeloideae and they generally resemble ...

'' spp. *'' Haworthiopsis'' spp. ('' H. koelmaniorum'', '' H. tessellata'', etc.) *''

'' spp. *'' Pleiospilos'' spp. (Questionable) *''

Peperomia ''Peperomia'' is one of the two large genera of the family Piperaceae. It is estimated that there are at least over 1,000 species, occurring in all tropical and subtropical regions of the world. They are concentrated in northern South America an ...

'' spp.: notably '' P. columella'' and '' P. nivalis'' *''

Sarracenia ''Sarracenia'' ( or ) is a genus comprising 8 to 11 species of North American pitcher plants, commonly called trumpet pitchers. The genus belongs to the family Sarraceniaceae, which also contain the closely allied genera '' Darlingtonia'' an ...

'' spp. Several other plant species have epidermal windows: *''

Cephalotus follicularis ''Cephalotus'' ( or ; Greek: ''κεφαλή'' "head", and ''οὔς''/''ὠτός'' "ear", to describe the head of the anthers) is a genus which contains one species, ''Cephalotus follicularis'' the Albany pitcher plant, a small carnivorous pi ...

'' *''

Darlingtonia californica ''Darlingtonia californica'' , also called the California pitcher plant, cobra lily, or cobra plant, is a species of carnivorous plant. It is the sole member of the genus ''Darlingtonia'' in the family Sarraceniaceae. This pitcher plant is nat ...

'' *'' Senecio rowleyanus'' Plants with leaf windows are sometimes known as ''window plants'', though this is also the

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

used to refer to ''Fenestraria rhopalophylla''.

References

{{Reflist Leaves Plant morphology

Functions

Species

See also

References