Arthrocaulon macrostachyum (Moric.) Piirainen & G.Kadereit
Arthrocnemum macrostachyum (Moric.) K. Koch, Salicornia macrostachya Moric., A. indicum subsp. glaucum (Delile) Maire & Weiller, A. glaucum (Delile) Ung.-Sternb., S. virginica Forssk.
Eng.: Glaucous glasswort. Spa.: Sapina, alacranera, almajo, sosa jabonera. Fre.: Arthrocnème, salicorne glauque. Ara.: Hardjem, balbal-jemal, h’mada, hamel, shenan.
Evergreen subshrub, hermaphrodite, generally upright, up to 1.5 m in height, very ramose. Fertile branches, herbaceous, are born opposite and are articulated, cylindrical, green and glabrous, seemingly without leaves. First segment of the branches ± flattened and angled, the following segments ± cylindrical. Leaves opposite, sessile, very small, forming a hyaline ring that surrounds the branch segment at the apex. Inflorescence a cylindrical and articulated spike (20-50 mm in length × 3-5 mm in diameter). Flowers grow in tri-floral cymes located at the base of the branch segments. The central flower is always slightly larger than the lateral ones; perianth with only one part (actually, 4 fused tepals, circular in cross section); anthers yellow 1-1.3 mm, style 0.4-0.7 mm. When flowers fall they leave a single cavity, not partitioned by membranous walls. Fruit an achene with a black and verrucous seed.
Flowering:
April to October.
Fruiting:
May to November.
Habitat:
Saline terrains with abundant moisture, coastal salt marshes, chotts, sabkhas and silty beds of inland rivers and streams.
Distribution:
Mediterranean region and surrounding areas. In North Africa it is common, becoming the dominant species in large salt marshes, from the Mediterranean to the Sahara and from the Atlantic to Asia Minor.
Observations:
Along the Draa River edges, near its mouth and in close proximity to Tan Tan (Morocco) there is population of A. franzii (Sukhor.) Piirainen & G.Kadereit (Arthrocnemum franzii Sukhor.), recently described species for 3 of the Cape Verde Islands (Sukhorukov & Nilova 2016). It differs from A. macrostachyum by being generally denser and more ramose, somewhat taller, with finer branches, and a number of features related to its reproduction such as: anthers are shorter (0.8-1 mm), style longer (1-1.5 mm) and seeds more elongated, with larger and more prominent papillae. It is a paleotropical species that extends towards the S up to Mauritania and reaches at least up to the Namibian coast (Rivas Mart. & J.C.Costa). Further studies are neeed to confirm which of the 2 species appears here and there throughout the Atlantic Sahara (from Tan Tan to Senegal) or whether they both coexist.
Another species of the genus was recently described in Sicily, and cited in Corsica and the northern coasts of Morocco: A. meridionalis Est.Ramírez, Rufo, Sánchez Mata & Fuente, which may also be present on the Mediterranean coasts of Algeria and Tunisia.
To differentiate the 3 species, A. Franzii has leaves about 5 mm long, double that of the other 2 species, also the length of the style (1-1.5 mm) is double. There are small morphological differences between the other 2 species in their stems, leaves, flowers and seeds, but one of the main differences is that A. macrostachyum is tetraploid (2n: 36) and A. meridionalis is diploid (2n: 18).
Conservation status:
A. macrostachyum is a common and even locally abundant species; it is not considered threatened. A. franzii and A. meridionalis should be further studied to determine their conservation status at a national and global level. Currently, they have not been assessed at a global level on the IUCN Red List of Threatened Species.