Our last example of the crucifers is the Sea Kale (Crambe maritima), a hardy perennial, commonly seen growing among the sand and shingle of the shore, which is the parent of the sea kale now so commonly cultivated in our market gardens. It may be readily recognised by the fine glaucous bloom of its stem, and its broad wavy toothed leaves of a glaucous grey colour. It grows to a height of about eighteen inches, and bears white flowers in June. The fruit is a two-jointed pouch, the upper being rounded and one-seeded, while the lower is stalk-like and barren. This plant is particularly common in the south-west of England, where the leaves are sometimes blanched for food by burying them in the sand.
Fig. 312.—The Sea Kale
One of the most striking plants of the coast is the Yellow Horned Poppy (Glaucium luteum) of the order Papaveraceæ, which contains the well-known poppies of corn-fields. The general characteristics of the order are two deciduous sepals, four petals, many stamens inserted below the ovary, and the ovary one-celled with membranous divisions. The plants of this species usually contain a milky juice, have alternate leaves without stipules, and the flowers, which are regular, generally nod when in bud. The Horned Poppy is a very conspicuous plant, usually growing quite alone on some inaccessible portion of the cliff, or among the pebbles or shingle not far from high-water mark. Its stem is glaucous and branched, and the large waved and deeply-cut leaves, which clasp the stem, are also of a glaucous hue. The flowers are rendered conspicuous by their large yellow petals, which, however, last only for a day, and are succeeded by the hornlike seed-pods that sometimes reach a foot in length.
Fig. 313.—The Horned Poppy
We will conclude our list of sea-side flowers by a brief mention of the Lesser Meadow Rue (Thalictrum minus), a variety of which (maritimum) grows on sandy shores. The Meadow Rue belongs to the Ranunculaceæ, as may be seen from the fruit of several distinct carpels, each containing a single seed, the corolla of distinct petals, and the numerous stamens inserted below the carpels. The normal form of the Lesser Meadow Rue, which grows freely in some chalky pastures and thickets, has leaves three or four times pinnate, and lax panicles of drooping flowers without any petals. The sea-side variety differs from this in having the stem leafless at the base, and the panicles leafless and broad. The flowers are greenish white, and bloom in July and August.
To assist the reader in the identification of sea-side flowers we append a list of the orders to which they belong, together with the principal distinguishing characteristics of each.