Sarcocornia

Sarcocornia
Sarcocornia quinqueflora
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Core eudicots
Order: Caryophyllales
Family: Amaranthaceae
Subfamily: Salicornioideae
Genus: Sarcocornia
A.J.Scott
Species

ca. 30 species, see text

Sarcocornia is a genus of flowering plants in the amaranth family, Amaranthaceae. They are known commonly as samphires, glassworts, or saltworts.[1] The genus has a cosmopolitan distribution,[2] and is most diverse in the Cape Floristic Region of South Africa.[3]

Description

The species of Sarcocornia are perennial herbs, subshrubs or shrubs.[4] They are taking an erect or prostrate, creeping form.[5] The new stems are fleshy and divided into joint-like segments. Older stems are woody and not segmented. The oppositely arranged leaves are borne on fleshy, knobby petioles, their base decurrent and connate (thus forming the segments), the blades forming small, triangular tips with narrow scarious margin.[1]

Sarcocornia pacifica, inflorescences

The terminal or lateral inflorescences are spike-like, made up of joint-like segments with tiny paired cymes emerging from the joints. Each cyme consists of three (rarely five) flowers completely embedded between the bract and immersed in the fleshy tissue of the axis. The flowers of a cyme are arranged in a transverse row, the central flower separating the lateral flowers, with tissue of the axis between them. The hermaphrodite or unisexual flowers are more or less radially symmetric, with a perianth of three or four fleshy tepals connate nearly to the apex, one or two stamens, and an ovary with two or three stigmas.[1]

The perianth is persistent in fruit. The fruit wall (pericarp) is membranous. The vertical seed is ellipsoid, with light brown, membranous, hairy seed coat, the hairs can be strongly curved, hooked, or conic, straight or slightly curved. The seed contains no perisperm (feeding tissue).[1]

The basic chromosome number is x=9. The species are diploid (18 chromosomes), tetraploid (36), hexaploid (54), or octoploid (72).[4]

Distribution and habitat

Sarcocornia is distributed worldwide, especially in warm-temperate regions with mediterranean climate, and to some extent in the subtropics. The distribution area covers North and South America, Europe (Mediterranean basin and Atlantic coasts with mild winters), southern Africa, and Australia.[4]

These halophytic plants often occur in wet saline habitat types, and occasionally in dry saline soils. They can be found in habitats such as estuaries, salt marshes, tidal flats, seacliffs, salt pans, and saline sediment in seasonal desert waterways.[3] An exception is Sarcocornia xerophila, growing in semidesert on quartz soils with low salinity.[4]

Phylogenetics

Sarcocornia/Salicornia began to evolve during the Mid Miocene from ancestors in Eurasia, developing four phylogenetic lineages: the first was the Eurasian Sarcocornia clade, further diversifying into the American Sarcocornia clade, then the Salicornia clade, and the South African/Australian Sarcocornia clade. As Salicornia (comprising all annual, more frost tolerant species) has evolved within Sarcocornia, the genus Sarcocornia is paraphyletic.[4]

The prostrate, mat-forming growth seems to have evolved several times independently. It is probably advantageous in habitats with prolonged flooding, high tidal movement and frost.[4]

Systematics

Sarcocornia fruticosa
Sarcocornia perennis
Sarcocornia neei
Sarcocornia quinqueflora

The genus Sarcocornia was first described in 1978 by Andrew John Scott,[6] thus separating the perennial species from the closely related annual Salicornia, additionally containing some species formerly belonging to Arthrocnemum. The type species is Sarcocornia perennis.[7]

The taxonomy of the genus has long been unclear. Study of the plants themselves is difficult because only fresh specimens can be used in the clear differentiation of taxa; many useful characters are not present in dry herbarium specimens.[1] Many sources accept the genus, but some authors continue to question its validity.[5] Molecular genetic studies revealed, that Sarcocornia/Salicornia form a monophyletic group, and Sarcocornia is paraphyletic.[4]

There are between 25 and 30 species in the genus,[4][8][9] forming three clades.[4] The center of diversity lies in southern Africa (Cape Floristic Region).[3][4]

References

  1. 1 2 3 4 5 Ball, Peter W. (2004). "Sarcocornia." in Flora of North America: North of Mexico Volume 4: Magnoliophyta: Caryophyllidae, part 1, Editorial Committee of the Flora of North America (Oxford University Press, 2004). ISBN 978-0-19-517389-5..
  2. ↑ Sarcocornia. PlantNET. National Herbarium of New South Wales, Royal Botanic Garden, Sydney.
  3. 1 2 3 Steffen, S., et al. (2010). "Revision of Sarcocornia (Chenopodiaceae) in South Africa, Namibia and Mozambique.". Systematic Botany 35(2), 390–408.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 Steffen, S; Ball, P.; Mucina, L.; Kadereit, G. (2015). "Phylogeny, biogeography and ecological diversification of Sarcocornia (Salicornioideae, Amaranthaceae)". Annals of Botany. 115 (3): 353–368. doi:10.1093/aob/mcu260.
  5. 1 2 Alonso, M. Á. and M. B. Crespo. (2008). "Taxonomic and nomenclatural notes on South American taxa of Sarcocornia (Chenopodiaceae)." In Annales Botanici Fennici 45(4), 241–254.
  6. ↑ Scott, A.J. (1978). "Reinstatement and revision of Salicorniaceae J. Agardh (Caryophyllales)". Botanical journal of the Linnean Society. 75 (4): 366–367. doi:10.1111/j.1095-8339.1977.tb01493.x.
  7. ↑ "Sarcocornia". Tropicos. Missouri Botanical Garden. Retrieved 12 August 2016.
  8. 1 2 3 Fuente, V. de la; Rufo, L.; Rodriguez, N.; Sánchez-Mata, D.; Franco, A.; Amils, R. (2016). "A study of Sarcocornia A.J. Scott (Chenopodiaceae) from Western Mediterranean Europe". Plant Biosystems. 150 (2): 353. doi:10.1080/11263504.2012.752414.
  9. 1 2 Yaprak, A. E. (2012). "Sarcocornia obclavata (Amaranthaceae) a new species from Turkey." Phytotaxa 49, 55–60.
  10. ↑ Piirainen, M. (2009). "Sarcocornia." In: P. Uotila, (ed.): Chenopodiaceae. In: Euro+Med Plantbase - the information resource for Euro-Mediterranean plant diversity.
This article is issued from Wikipedia - version of the 8/12/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.