Salsola schweinfurthii

S. rosmarinus, like its relative S. longifolia, has opposite fleshy leaves and winged outgrowths arising above the middle of the notch-like perianth parts. However, unlike its relative, this species has leaf bases almost completely joined at the nodes without any longitudinal channel running down the internode. It also contains a dense tuft of white hairs in the axil of each leaf. The perianth parts and wings of the genus Soda are unequally developed in each flower. The wings of the plant overlap, while the upper part of the perianth is broad at its base. The plant is classified as a xerophyte, having adapted itself to places with little water. It blossoms in late March, April, and early May.

The plant grows mainly in salt flats (Arabic: sabkha) in hard soil surfaces, and can also be found growing along riverine gulches (Arabic: wadi) and in drainage runnels that have alkaline and saline soils, subsequently accumulating in its leaves a high quantity of sodium and chloride (chlorine ions). It thrives in silty soil which is very slippery and muddy when wet, but becomes baked hard with a flaking surface which breaks up into a fine dust when dry, and can especially be seen growing on hummocks in such terrain.

The species has been used in antiquity for the production of potash, hence its Arabic name, ušnān. The 10th-century Arab physician, al-Tamimi, described the plant in his day as being imported into Palestine, Egypt, and other regions from the riverine gulches around the vicinity of Amman, in Transjordan, and used in the production of an alkali soap (Arabic: غاسول = ġāsūl) and of cleaning agents. According to al-Tamimi, the plants were gathered in their fresh, green state in large bundles, transferred to furnaces made with plastered floors and stone spouts, where they were cast inside, beneath which were laid large timbers that were set aflame, causing the melting alkali substance to drip down by the spouts into a threshing floor directly below. The liquid would be collected and eventually become hardened when it cooled, the finished product resembling a hard, black-colored stone. The stone-like mineral could be broken up into smaller fragments and used as a laundry detergent.

Some of the salt bushes produced a type of potassium alum (Arabic: shab) that was brownish in color, having a strong alkalinity and burning effect when tasted. …