To the order Gentianaceæ belong the Centaury (Erythræa), three out of the four British species of which grow on sandy shores. In the flowers of this order the calyx has from four to ten lobes; the stamens also number four to ten, and are alternate with the lobes of the corolla. The ovary is one- or two-celled, and the fruit is a berry with many seeds. The leaves are usually opposite and entire, and the flowers are generally showy, regular, and solitary. Erythræa has a funnel-shaped corolla, five stamens, and two stigmas, on a deciduous style; and in all our species the flower is rose-coloured. The Dwarf Centaury (E. pulchella), which is common on some sandy shores, is much smaller than the species that thrives in pastures, being only two or three inches in height. Its stem is also more freely branched, and its flowers are axillary and terminal. The Tufted Centaury (E. littoralis) and the Broad-leaved Centaury (E. latifolia) occur in similar situations, but are comparatively rare. They are both small species, the former with an unbranched stem, narrow leaves, and corymbose inflorescence; and the latter with branched stem, broad elliptical leaves, and flowers in dense forked tufts.
Fig. 298.—The Dwarf Centaury
The extensive order Compositæ contains comparatively few sea-side plants, and, in dealing with these, we pass to another division of the monopetalous flowers, in which the ovary is inferior and the stamens are on the corolla. The order includes those herbaceous plants in which sessile flowers are collected together into compound heads (capitula) surrounded by a whorl of bracts. The corolla is either tubular or strap-shaped (ligulate), the stamens four or five in number, and the fruit one-seeded, usually crowned with the limb of the calyx in the form of a scaly feathery or hairy pappus.
The Little Lettuce (Lactuca saligna) is found in chalky pastures near the east and south-east coasts, growing to a height of about a foot, and bearing heads of yellow flowers in July and August. All the flowers are ligulate and perfect, the pappus is composed of silvery hairs, and the fruit is compressed and beaked, the beak being twice as long as the fruit. The leaves are smooth, linear, and sagittate, terminating in a sharp point. The Sea-side Cotton Weed (Diotis maritima) is occasionally met with on sandy shores, and may be recognised by its dense coating of downy hair, its sessile obtuse leaves, and heads of yellow flowers forming a corymb. The heads are discoid, and the fruit has no pappus. The Sea Wormwood (Artemisia maritima) is a common sea-shore composite, bearing drooping heads of reddish-white flowers in August. This is another of the downy species, its pinnatifid leaves having quite a woolly appearance. The capitulum contains but few flowers, all of which are perfect; and the fruit has no pappus. A variety of this plant is sometimes seen, with dense erect capitula. The Sea Aster or Michaelmas Daisy (Aster tripolium) of salt marshes may be known by the yellow discs and purple rays of its flower heads, which are arranged in a corymb. The florets of the ray form a single row, and the fruit has a hairy pappus. The leaves of this plant are spatulate and fleshy. A variety occurs in which the purple florets of the ray are absent. The Golden Samphire (Inula crithmoides) is a very local sea-side plant, being found principally on the south-west coast. Its leafy stems grow to a height of a foot or more, and bear yellow heads of flowers that radiate in all directions. The leaves are linear, acute, and fleshy, and the bracts are linear and imbricated. Our last example of the sea-side composites is the Sea-side Corn Feverfew or Scentless Mayweed, which is a variety of Matricaria inodora of waste places. The leaves are sessile and pinnatifid, with very narrow segments, and the white flowers grow in solitary heads. The maritime variety differs from the normal form in having fleshy leaves.
We next deal with another very extensive order (the Umbelliferæ), which, however, has only three or four representatives on the shore, and these introduce us to the last great division of the flowering plants, namely, the Polypetalous Dicotyledons, in which the petals are not united. Of these we shall first deal with that subdivision in which the stamens are attached at the side of or upon the ovary.
The most obvious characteristic of the Umbelliferæ is that implied in the name—the arrangement of the flowers in that form of inflorescence, called the umbel, in which the pedicels all branch from one point in the main stalk, and are such that the flowers are all approximately on a level. The flowers are mostly small and white, with five sepals (when present), five petals, and five stamens. The inferior ovary is two-celled, bearing two styles; and the fruit separates into two dry one-seeded carpels that are ribbed longitudinally.
Our first example of this group is the Sea Carrot, a variety of the Wild Carrot (Daucus carota). In the ordinary form, which is so common in fields, the leaflets are pinnatifid, with acute segments; and the central flowers of each umbel are purple, while the outer ones are white. The umbel, when in fruit, is concave above. The maritime variety differs from this in having fleshy leaves, and the umbel convex above when in fruit. The Sea Samphire (Crithmum maritimum) grows on the rocks close to the sea, and thrives well where there is hardly a vestige of soil. It usually grows to a height of seven or eight inches, bearing greenish-white flowers surrounded by a whorl of very narrow leaves. The other leaves are glaucous and bi-ternate, the leaflets being narrow, fleshy, and tapering towards both ends. On cliffs near the sea, especially in chalky districts, we meet with the Fennel, with its finely-divided leaves, split up into numerous capillary leaflets, and its small yellow flowers without bracts. It may be distinguished from other closely-allied plants by the form of the fruit, which is flattened at the sides. It is grown in some parts for use as a potherb, and an aromatic oil is also obtained from the seeds. The plant grows to a height of four or five feet, but there is a smaller variety known as the Sweet Fennel, and distinguished by the stem being compressed at the base. Our next example of the Umbelliferæ is the Sea Holly (Eryngium maritimum), easily distinguished from the other umbellifers by its spiny glaucous leaves, and the thistle-like heads of blue flowers surrounded by a whorl of spiny bracts. Its fleshy creeping roots were formerly gathered largely for the purpose of converting them into the once-prized ‘candied eryngo root,’ which is still prepared in a few of the fishing villages of our coast. The lower leaves of this plant are spinous and very glaucous, and the upper ones palmate. The venation is particularly strong and durable, so that the leaves and flowers are used largely by the sea-side cottagers in the construction of skeleton bouquets and wreaths. Another plant of the same genus—The Field Eryngo (E. campestre)—is occasionally seen on sandy shores. It differs from the last in having ternate radical leaves with pinnatifid lobes, and the upper leaves, bi-pinnatifid. Our last example of the sea-side umbellifers is the Wild Celery (Apium graveolens) of salt marshes and ditches. This is the plant from which our highly-valued garden celery has been produced, and it is remarkable that this sweet crisp and wholesome vegetable has been derived from a wild plant of coarse taste and odour, the acrid sap of which is highly irritating if not dangerous. The plant may be known by its furrowed stem, and ternate leaves, the leaflets of the lower leaves being round and lobed, while those of the upper ones are notched. The umbels are sessile or nearly so, the flowers have no calyx, and the fruit has five prominent ridges.