''Sedum album'', the white stonecrop, is a

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

of the genus ''

Sedum ''Sedum'' is a large genus of flowering plants in the family Crassulaceae, members of which are commonly known as stonecrops. The genus has been described as containing up to 600 species, subsequently reduced to 400–500. They are leaf succulen ...

'' in the family

Crassulaceae The Crassulaceae (from Latin ''crassus'', thick), also known as the stonecrop family or the orpine family, are a diverse family of dicotyledon flowering plants characterized by succulent leaves and a unique form of photosynthesis, known as Crass ...

. It is found in the northern temperate regions of the world, often growing in crevices or free-draining rocky soil. As a long-day plant it grows

vegetatively Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spec ...

for most of the year and flowers in summer.

Taxonomy

Three subspecies ''album'', ''micranthum'' (Bastard ex DC.) Syme and ''teretifolium'' Syme have been described.

Description

White stonecrop is a tufted perennial herb that forms mat-like stands. Much of the year the stems are short, semi prostrate and densely clad in leaves. At the flowering time in July and August, the stems lengthen and are erect, occasionally branched and often pinkish-brown. The leaves are alternate, fleshy and nearly cylindrical with a blunt, rounded tip. They are also sometimes tinged with pink, especially in drought-stressed plants. The starry flowers form a dense cyme. The calyx has five fleshy sepals fused at the base, the corolla consists of five regular white petals, there are ten stamens, a separate gynoecium and five pistils. The fruit is five united, many-seeded follicles.

Habitat

White stonecrop is a low-growing plant that cannot compete with more vigorous fast-growing species. It is specially adapted for growing on thin dry soils and can be found on walls, dry banks, seashore rocks and in rocky meadows.

Physiology

''Sedum album'' is able to

acclimate Acclimatization or acclimatisation ( also called acclimation or acclimatation) is the process in which an individual organism adjusts to a change in its environment (such as a change in altitude, temperature, humidity, photoperiod, or pH), a ...

to its environment. It can switch between

C3 carbon fixation carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, along with and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of 3-phosph ...

and

crassulacean acid metabolism Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night. ...

(CAM) depending on the availability of water. CAM saves water as the

stomata 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 bor ...

on its leaves only open to allow to diffuse into the leaves at night when the temperature (and therefore

evapotranspiration Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpi ...

) is lower. Drought stressed plants are also more susceptible to

photoinhibition Photoinhibition is light-induced reduction in the photosynthetic capacity of a plant, alga, or cyanobacterium. Photosystem II (PSII) is more sensitive to light than the rest of the photosynthetic machinery, and most researchers define the term ...

which CAM may help to protect against.

Cultivation

Hardy in Zones 3-9.Missouri Botanical Garden: Sedum album subsp. teretifolium 'Murale'
/ref> File:Sedum_acclimation2.JPG, The plant on the left is relatively drought stressed and the one on the right is well watered

References

{{Taxonbar, from=Q253636

album An album is a collection of audio recordings issued on compact disc (CD), Phonograph record, vinyl, audio tape, or another medium such as Digital distribution#Music, digital distribution. Albums of recorded sound were developed in the early ...

Flora of Lebanon Plants described in 1753 Taxa named by Carl Linnaeus Flora of Malta Crassulaceae