Species formerly placed in 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]
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]
Taxonomy
The genus Sarcocornia was first described in 1978 by A J Scott.[6] It separated the perennial species from the closely related annual Salicornia senus stricto, additionally containing some species formerly belonging to the former genus Arthrocnemum. The type species is Sarcocornia perennis.[7]
Sarcocornia/Salicornia began to evolve during the middle 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. When Salicornia is separated from Sarcocornia to comprise all the annual, more frost tolerant species, the genus Sarcocornia is paraphyletic, since Salicornia evolved within Sarcocornia.[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]
A molecular phylogenetic study in 2017 confirmed the paraphyly of Sarcocornia, and merged the genus into Salicornia.[8]
^Sarcocornia. PlantNET. National Herbarium of New South Wales, Royal Botanic Garden, Sydney.
^Steffen, S.; et al. (2010). "Revision of Sarcocornia (Chenopodiaceae) in South Africa, Namibia and Mozambique". Systematic Botany. 35 (2): 390–408. doi:10.1600/036364410791638379. S2CID85950463.
^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.
