Lithophytes are

plants Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclude ...

that grow in or on

rocks In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's o ...

. They can be classified as either epilithic (or epipetric) or endolithic; epilithic lithophytes grow on the surfaces of rocks, while endolithic lithophytes grow in the crevices of rocks (and are also referred to as chasmophytes). Lithophytes can also be classified as being either obligate or facultative. Obligate lithophytes grow solely on rocks, while facultative lithophytes will grow partially on a rock and on another substrate simultaneously.

Nutrients

Lithophytes that grow on land feed off nutrients from rain water and nearby decaying plants, including their own dead tissue. It is easier for Chasmophytes to acquire nutrients because they grow in fissures in rocks where soil or organic matter has accumulated. For most Lithophytes, nitrogen is only available through interactions with the atmosphere. The most readily available form of nitrogen in the atmosphere is the gaseous state of ammonia (NH3). Lithophytes consume atmospheric ammonia through a concentration gradient that allows the compound to traverse the plants' apoplast. Once free in the apoplast, gaseous ammonia is absorbed into metabolic cells by the enzyme glutamine synthetase. To be able to absorb the few nutrients available on rocks or rocky substrates efficiently, Lithophytes have evolved certain adaptations. They possess decreased numbers of root hairs and larger root diameters in comparison to other plant species. To add to this nutrient uptake efficiency, lithophytic plants have increased their relationship with arbuscular mycorrhizal fungi and dark septate endophyte fungi. These two types of fungi live inter- and intracellularly with the roots of Lithophytes and a wide variety of other plant species. They increase the uptake of nutrients and water and have been found in greater concentrations in Lithophytes.

Walls colonised as artificial cliffs by lithophytes

Asarina procumbens cascading down wall beside Paxton church gatepost

Walls, and other exposed stonework, are colonised by plants in a similar way to the colonisation of
cliff In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on coa ...
s and
scree Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. Talus deposits typically h ...
. These natural features are uncommon, especially in the lowlands, so walls are important for the conservation of plants which might otherwise be very isolated. Some wall plants even have ‘wall’ or ‘muralis’ as part of their common or scientific name such as Wall-flower (''
Erysimum cheiri ''Erysimum cheiri'', syn. ''Cheiranthus cheiri'', the wallflower, is a species of flowering plant in the family Brassicaceae (Cruciferae), native to Greece, but widespread as an introduced species elsewhere. It is also treated as a hybrid under ...
'') or Ivy-leaved toadflax ('' Cymbalaria muralis''), which shows their long established relationship with these man-made structures.

English Heritage English Heritage (officially the English Heritage Trust) is a charity that manages over 400 historic monuments, buildings and places. These include prehistoric sites, medieval castles, Roman forts and country houses. The charity states that i ...

''Landscape Advice Note: Vegetation on Walls''

Examples

Examples of lithophytes include many

orchids Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowering ...

such as ''

Dendrobium ''Dendrobium'' is a genus of mostly Epiphyte, epiphytic and Lithophyte, lithophytic orchids in the Family (biology), family Orchidaceae. It is a very large genus, containing more than 1,800 species that are found in diverse habitats throughout m ...

'' and ''

Paphiopedilum ''Paphiopedilum'', often called the Venus slipper, is a genus of the lady slipper orchid subfamily ''Cypripedioideae'' of the flowering plant family Orchidaceae. The genus comprises some 80 accepted taxa including several natural hybrids. The g ...

'',

bromeliads The Bromeliaceae (the bromeliads) are a family of monocot flowering plants of about 80 genera and 3700 known species, native mainly to the tropical Americas, with several species found in the American subtropics and one in tropical west Africa, ...

such as ''

Tillandsia ''Tillandsia'' is a genus of around 650 species of evergreen, perennial flowering plants in the family Bromeliaceae, native to the forests, mountains and deserts of northern Mexico and south-eastern United States, Mesoamerica and the Caribbean to ...

'', as well as many

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except th ...

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthesis, photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from u ...

and

liverwort The Marchantiophyta () are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of ge ...

s. Lithophytes have also been found in many other plant families, such as, Liliaceae, Amaryllidaceae, Begoniaceae, Caprifoliaceae, Crassulaceae, Piperaceae and Selaginellaceae.

Carnivorous plants

As nutrients tend to be rarely available to lithophytes or chasmophytes, many species of

carnivorous plants Carnivorous plants are plants that derive some or most of their Plant nutrition, nutrients from trapping and consuming animals or protozoans, typically insects and other arthropods. Carnivorous plants still generate some of their energy from ph ...

can be viewed as being pre-adapted to life on rocks. By consuming prey, these plants can gather more nutrients than non-carnivorous lithophytes.McPherson, S.R. (2010). ''Carnivorous Plants and their Habitats. Volume 1.'' Redfern Natural History Productions, Poole. pp. 176–180. Examples include the

pitcher plant Pitcher plants are several different carnivorous plants which have modified leaves known as pitfall traps—a prey-trapping mechanism featuring a deep cavity filled with digestive liquid. The traps of what are considered to be "true" pitcher ...

s ''

Nepenthes campanulata ''Nepenthes'' () is a genus of carnivorous plants, also known as tropical pitcher plants, or monkey cups, in the monotypic family Nepenthaceae. The genus includes about 170 species, and numerous natural and many cultivated hybrids. They are mo ...

'' and ''

Heliamphora exappendiculata ''Heliamphora exappendiculata'' ( Latin: ''ex'' = without, ''appendicula'' = small appendage) is a species of marsh pitcher plant native to the Chimantá and Aprada Massifs of Bolívar state, Venezuela.McPherson, S., A. Wistuba, A. Fleischma ...

'', many ''

Pinguicula ''Pinguicula'', commonly known as the butterworts, is a genus of carnivorous flowering plants in the family Lentibulariaceae. They use sticky, glandular leaves to lure, trap, and digest insects in order to supplement the poor mineral nutrition t ...

'' and several ''

Utricularia ''Utricularia'', commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species (precise counts differ based on classification opinions; a 2001 publication lists 215 species).Salmon, Br ...

'' species.

Tennyson poem inspired by lithophyte

In the year 1863,

Alfred, Lord Tennyson Alfred Tennyson, 1st Baron Tennyson (6 August 1809 – 6 October 1892) was an English poet. He was the Poet Laureate during much of Queen Victoria's reign. In 1829, Tennyson was awarded the Chancellor's Gold Medal at Cambridge for one of his ...

was moved to write his short and pithy poem of

metaphysical Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...

speculation

Flower in the Crannied Wall "Flower in the Crannied Wall" is a poem composed by Alfred Tennyson in 1863 beside the wishing well at Waggoners Wells. The poem uses the image of a flowering plant - specifically that of a chasmophyte rooted in the wall of the wishing well - ...

upon contemplating an unnamed lithophyte growing out of the masonry of the

wishing well A wishing well is a term from European folklore to describe wells where it was thought that any spoken wish would be granted. The idea that a wish would be granted came from the notion that water housed deities or had been placed there as a ...

at Waggoners Wells. National_Trust_wishing_well_sign,_Waggoners_Wells,_Grayshott

Flower in the crannied wall, I pluck you out of the crannies, I hold you here, root and all, in my hand, Little flower—but if I could understand What you are, root and all, and all in all, I should know what God and man is.''Poems of Alfred Lord Tennyson.'' Eugene Parsons (Introduction). New York: Thomas Y. Crowell Company, 1900.

Gallery

File:Erinus alpinus plant in flower.jpg, ''

Erinus alpinus ''Erinus alpinus'', the fairy foxglove, alpine balsam, starflower, or liver balsam, is a species of flowering plant in the family Plantaginaceae (previously in the family Scrophulariaceae), native to Central and Southern Europe. and also to M ...

'', the fairy foxglove, growing out of a crack in the mortar of a stone wall File:Lithophytes at Chatswood West.jpg, Rock Felt Fern, Elkhorn fern, Birds Nest Fern and

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) ''sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hornw ...

growing on

Hawkesbury Sandstone Sydney sandstone is the common name for Sydney Basin Hawkesbury Sandstone, one variety of which is historically known as Yellowblock, and also as "yellow gold" a sedimentary rock named after the Hawkesbury River north of Sydney, where thi ...

Chatswood West Chatswood West is a suburb on the Lower North Shore of Sydney, in the state of New South Wales, Australia. Chatswood West is located 11 kilometres north-west of the Sydney central business district, in the local government areas of the City of ...

, Australia

References

Plant morphology {{Botany-stub he:מורפולוגיה של הצמח - מונחים#צורות חיים ושלבי חיים של צמחים