The group Spyridiaceæ contains only one English plant, Spyridia filamentosa, which is curiously and irregularly branched, the branches being articulate and of a pinky red. One of its kinds of fruit, consisting of crimson spores, is contained in a transparent network basket, formed by the favellæ, or short branches, whence its name.
The Cryptonemiaceæ are very numerous in genera and species. They all have inarticulate branches, some are thread-like. Grateloupia filicina is a neat little plant, met with rarely on the south and west coasts. Gigartina mamillosa, a common plant everywhere, is the plant sold, along with Chondrus crispus, as Irish or Carrageen moss. A handsome little plant, Stenogramme interrupta, is very rare, but it has been gathered both on the Irish and English coasts. The Phyllophoræ, one species of which is frequent on all our shores, may be recognised by the way in which the points and surfaces of their fronds throw out proliferous leaves. Gymnogongrus has two British species, one much resembling Chondrus crispus, already named, of which it was formerly considered a congener. Their fructification is however very different. Ahnfeltia plicata is a curious wiry, entangled plant, almost black in colour, and like horsehair when dry, and can scarcely be mistaken. Cystoclonium purpurascens is very commonly cast up by the tide on most of our coasts. It varies in colour, but is easily distinguished by the spore-bearing tubercles imbedded in its slender branches. Callophyllis laciniata is a handsome species, of a rich crimson colour, and sometimes a foot square. It can scarcely have escaped the notice of the sea-side visitor, for it is widely distributed and often thrown out in great abundance; one writer describes the shore near Tynemouth as having been red for upwards of a mile with this superb sea-weed. Kalymenia reniformis is another of the broad, flat Algæ, but it is scarcer, and of a colour not so conspicuous. Among the most frequent of our sea-weeds, both as growing in the rock pools and cast ashore, is Chondrus crispus, already twice referred to in connexion with its officinal uses. It is very variable in form, one author figuring as many as thirty-six different varieties. ([Fig. 6.]) Chylocladia clavellosa, which is sometimes cast ashore a foot and a half long, is closely set with branches, and these again clothed with branchlets in one or two series. The whole plant is fleshy, of a rose-red or brilliant pink colour, turning to golden yellow in decay. There is another small species, confined to the extreme north of Britain. Halymenia ligulata is another flat red weed, but sometimes very narrow in its ramifications. Furcellaria fastigiata has a round, branched, taper stem, swollen at the summit, which contains the fruit, consisting of masses of tetraspores in a pod-like receptacle. Schizymenia edulis, better known perhaps by its old name Iridea, is a flat, inversely egg-shaped leaf with scarcely any stem. It is one of the edible Algæ, and pretty frequent in shady rock pools. Gloiosiphonia capillaris is a remarkably beautiful plant, and not common, being confined to certain parts of the southern coasts. The stem is very soft and gelatinous; the spores are produced in red globular masses imbedded in the marginal filaments, which have a fine appearance under the microscope when fresh.
Fig. 7. Rhodomenia palmata.
Fig. 8. Wormskioldia sanguinea.
The Rhodomeniaceæ are purplish or blood-red sea-weeds, inarticulate, membranaceous, and cellular. Among the dark-coloured is Rhodomenia palmata, better known as dulse, a common and edible species. ([Fig. 7.]) Wormskioldia sanguinea is not only the most beautiful sea-weed, but the finest of all leaves or fronds. It is usually about six inches long, but sometimes nearly double that length and six inches broad, with a distinct midrib and branching veins, and a delicate wavy lamina, pink or deep red. The fruit is produced in winter from small leaflets growing upon the bare midrib. ([Fig. 8.]) The commonest of all red sea-weeds on our coast, one of the most elegant, and much sought after by sea-weed picture makers, Plocamium coccineum, belongs to this group. Calliblepharis ciliata and jubata are coarser plants, the latter being the more frequent. They were formerly included in the genus Rhodymenia, from which they were removed when their fruit was better understood.