Fig. 294.—The Prickly Salt Wort
The Oraches (genus Atriplex) resemble the Purslanes in the granular mealiness of the foliage, and the two are so closely allied that they are often placed in the same genus. Oraches are most readily distinguished among the Chenopods by the two bracts which enclose the fruit and enlarge after flowering; and, like the Purslanes, they have unisexual flowers, both male and female being on the same plant. Three of our five British species are sea-side plants. The Frosted Sea Orache (A. arenaria) grows on sandy shores, about six or eight inches in height, and flowers during late summer and autumn. It may be known by its buff-coloured stem, with triangular or rhomboidal, jagged, silvery leaves, and clusters of sessile flowers in the axils of the leaves. Another species (A. Babingtonii) may be seen on both rocky and sandy shores, usually from one to two feet in height, and flowering from July to September. Its stem is procumbent, green with reddish stripes; leaves oval-triangular, lanceolate towards the top, three-lobed at the base of the stem, light green, with a mealy surface; flowers in terminal clusters as well as in the axils of the leaves. A third species—the Grass-leaved Orache (A. littoralis) grows in salt marshes. All its leaves are grass-like and entire, and the stem is generally marked with reddish stripes as in A. Babingtonii. The flowers, too, are in sessile axillary clusters only. This plant reaches a height of from one to two feet, and flowers in the late summer.
The Prickly Salt Wort (Salsola kali) is a very common sea-side plant on some of our coasts, and may be recognised at a glance by its general form and habit. The stem is very much branched and prostrate, forming a very bushy plant about a foot in height. It is also very brittle and succulent, furrowed and bristly, and of a bluish-green colour. The leaves are fleshy, awl-shaped, nearly cylindrical, with a spiny point, and little prickles at the base. The flowers are axillary and solitary. This plant and its exotic allies are very rich in alkaline salts, particularly carbonate of soda, and were formerly the principal source from which this compound was obtained.
Fig. 295.—The Creeping Glass Wort
Our last example of the sea-side chenopods is the Glass Wort (Salicornia), which thrives in salt marshes. In this genus the stem is jointed and the flowers bisexual. The Jointed Glass Wort (S. herbacea) is common in most salt marshes, where its erect, herbaceous, leafless stem may be seen growing to a height of a foot or more. The joints are thickened upwards, and shrink to such an extent when dry that the upper part of each segment of the stem forms a membranous socket into which fits the base of the next segment above. The flowers are arranged in dense tapering spikes, also jointed, with a cluster of three flowers on the two opposite sides of the base of each segment. Each flower is composed of a perianth, closed with the exception of a small aperture through which the stigma and, later, the stamens protrude. The Creeping Glass Wort (S. radicans) has a woody procumbent stem, with the joints only slightly thickened, and the spikes do not taper so much as in S. herbacea. Both these plants yield considerable quantities of soda, and they are named ‘Glass Wort’ because they formerly constituted one of the sources from which soda was obtained for the manufacture of glass.
We now come to those flowers in which both calyx and corolla exist, and shall deal first with the division Gamopetalæ or Monopetalæ, in which the petals are united.