BRITISH ALGE.

SERIES I. MELANOSPERMEÆ.

TRIBE 1. FUCOIDEÆ.

I. SARGASSUM. Ag.

Frond furnished with distinct, stalked, nerved leaves, and simple, axillary, stalked air-vessels. Receptacles small, linear, tuberculated, mostly in axillary clusters. Seeds in distinct cells.-Name, altered from sargazo, the Spanish term for the masses of floating seaweed common in some latitudes.

1. S. vulgare, Ag.; stem flat, slender, alternately branched; leaves linear-lanceolate, serrated, dotted with mucous pores; air-vessels few, sphærical, on flat stalks; receptacles cylindrical, racemose. Grev. Alg. Brit. p. 2, t. 1; Hook. Br. Fl. ii. p. 264; E. Bot. t. 2114.

Occasionally cast ashore. Orkneys, Mr. P. Neill.-Stem 12-18 inches long, pinnated with simple branches. Leaves very variable in breadth. Colour, when recent, olive, reddish brown when dry.

2. S. bacciferum, Ag.; stem cylindrical, slender, much branched, flexuose; leaves linear, serrated, mostly without pores; air-vessels abundant, sphærical, on cylindrical stalks; receptacles unknown. Grev. Alg. Brit. p. 3; Hook. Br. Fl. p. 264; E. Bot. t. 1967.

ii.

Occasionally cast ashore with the preceding. Orkneys, Mr. P. Neill. Shore of Castle Eden Dean, Durham, Mr. W. Backhouse.-Root unknown. Stems extremely brittle. Leaves 1-2 inches long, and about a line wide, of a very pale olive colour when recent. species have no just claim on our Flora, being natives of the tropics, occaThis and the preceding sionally driven, together with cocoa-nuts and other tropical productions, by

the force of the western currents on our Atlantic coasts.

II. CYSTOSEIRA. Ag.

Frond much branched, occasionally leafy at base; branches becoming more slender upwards, and containing strings of simple air-vessels within their substance. Receptacles cylindrical, small, tuberculated or prickly, terminal. distinct cells. Name, xvoris, a bladder, and σuga, a chain; Seeds in

C

because the air-vessels are generally arranged in strings or series.

1. C. ericoides, Ag.; stem thick, woody, short, cylindrical, beset with numerous, slender, filiform branches, variously divided, and densely clothed with small, spine-like, awl-shaped ramuli (or leaves); air-vessels small, solitary near the apices; receptacles cylindrical, terminal, spiny. Grev. Alg. Brit. p. 4; Hook. Br. Fl. ii. p. 265; E. Bot. t. 1968; Wyatt, Alg.

Danm. No. 1.

Rocks in the sea, chiefly in the S. West of England and West and South of Ireland; common. Yarmouth Beach, Mr. Turner. Port Rush, North of Ireland, Mrs. Ovens. Perennial. Summer and autumn.-Root a large and very hard disk. Frond one or two feet long, remarkably bushy, of a fine olive or yellowish green when removed from the water, but appearing, whilst growing beneath the surface, to be clothed with the richest iridescent tints. Air-vessels generally solitary, and immediately subtending the terminal receptacles, very small; sometimes scattered along the branches.

2. C. granulata, Ag.; stem cylindrical, covered with elliptical knobs, each of which bears a slender, repeatedly divided, dichotomo-pinnated, cylindrical branch, irregularly set with scattered, incurved, awl-shaped, spine-like ramuli; air-vessels small, linear-oblong, two or three together in the upper part of the branches; receptacles elongated. Grev. Alg. Brit. p. 5, t. 2; Hook. Br. Fl. ii. p. 265; E. Bot. t. 2169; Wyatt, Alg. Danm. No. 101.

Rocky pools left by the tide on the South coasts of England_and Ireland, not uncommon. Devon and Cornwall, Mrs. Griffiths, Mr. Rashleigh, &c. Bantry Bay, Miss Hutchins. Youghal, Miss Ball. Magilligan, Co. Derry, Mr. G. Hyndman. Larne, Dr. Drummond. Growing in pools at Ardglass, Co. Down, Mr W. Thompson. Perennial. Summer.-Root a flattish disk. Stem about the thickness of a goose-quill, 7 or 8 inches high; branches very slender, a foot or more in length, very much divided, each having at its base a hard bulbous knob, which forms one of the most striking characters of the species. Colour a semi-transparent olive-green.

3. C. barbata, Ag.; frond cylindrical, stem furnished with elliptical knobs, each producing a branch many times dicho tomo-pinnate and filiform; air-vessels lanceolate, chain-like; receptacles ovate-elliptical, mucronate. Grev. Alg. Brit. p. 6; Hook. Br. Fl. ii. p. 265; E. Bot. t. 2170.

In the sea. Said to have been gathered on the Devonshire coast by Hudson; a native, chiefly, of the Mediterranean.-Distinguished from the last species by the receptacles being tipped with a spine-like point.

4. C. foeniculacea, Grev.; stem compressed, branches long, slender, rough with hard points, repeatedly dichotomo-pinnate; air-vessels small, solitary or two together, elliptic oblong, near the apices of the branches; receptacles minute,

linear-lanceolate. Grev. Alg. Brit. p. 7; Hook. Br. Fl. ii. p. 265; Turn. Hist. t. 252; E. Bot. t. 2130 and t. 2131; Wyatt, Alg. Danm. No. 51.

Coasts of the South and S. West of England and Ireland. Perennial. Summer.-Frond 1-2 feet long; stem destitute of knobs, nearly cylindrical, 4-6 inches high, and bearing numerous, long, sub-simple, slender branches, which are generally naked toward the base, but in the upper part closely set with distichous, alternately pinnate or sub-dichotomous, secondary branches. In the young state, and especially when growing in deep water, this plant is furnished with long, flat, pinnatifid leaves, 1-2 lines broad, midribbed, dotted, and irregularly serrated at the margins, and then constitutes the Cis. discors of Agardh (Fucus discors, L.; E. Bot. t. 2131); but these leaves, as was long since shown by Mrs. Griffiths, and has been confirmed by Turner, Greville, and subsequent observers, finally elongate and become branches, and the plant assumes the appearance as above de

scribed.

5. C. fibrosa, Ag.; stem woody, compressed, bushy, very much branched; branches slender, alternately branched, the upper ones repeatedly divided, and furnished with lineari-setaceous, flattish ramuli; air-vessels elliptical, mostly solitary, immersed in the branches remote from the apices; receptacles filiform, much elongated. Grev. Alg. Brit. p. 8; Hook. Br. Fl. ii. p. 266; E. Bot. t. 1969; Wyatt, Alg. Danm. No. 52. In the sea, chiefly on the southern coasts. Perennial. Summer. Coast of Yorkshire, Hudson. Yarmouth, rare, Mr. Wigg. West of Ireland. Shores of Antrim, Mr. Templeton. Portrush, Mr. D. Moore.-Root, a hard, spreading disk. Frond three feet long or more; stem mostly undivided, gradually diminishing upwards, and thickly set with distichous, alternate branches, slightly swollen at base, and furnished with one or two series of smaller ramuli, the terminal ones being long and setaceous. vessels larger than in any other British species, and generally occurring near the base of the branches, solitary or two or three together. Colour olivegreen.

III. HALYDRYS. Lyngb.

Air

Frond compressed, coriaceous, linear, pinnated with distichous branches. Air-vessels lanceolate, stalked, divided into several cells by transverse septa. Receptacles lanceolate, stalked, compressed. Seeds in distinct cells. Grev.-Name, ans, anos, the sea, and devs, an oak or tree.

1. H. siliquosa, Lyngb.; branches linear, very narrow; airvessels compressed, linear-lanceolate, slightly constricted at the septa, mucronate. Grev. Alg. Brit. p. 9, t. 1; Hook. Br. Fl. ii. p. 266; E. Bot. t. 474; Wyatt, Alg. Danm. No. 53. -B, minor; smaller in every part, with fewer vesicles. Turn. Syn. i. p. 61.

On rocky coasts, very common. Perennial. ẞ, in shallow pools left by

the tide.-Root an expanded disk, from which spring several fronds 1--4 feet long, alternately branched; branches about a line wide, pinnated with similar ramuli, and in the upper part with air-vessels and receptacles. Airvessels resembling pods or siliquæ, whence the specific name. The beautiful Fucus osmundaceus, Turn. Hist. t. 105, appears to be a second species of this genus, but its fruit is still a desideratum.

IV. Fucus. Linn. Ag.

Frond plane, compressed or cylindrical, linear-dichotomous (rarely pinnated), coriaceous. Air-vessels, when present, innate in the frond, simple, large. Receptacles terminal (except in F. nodosus and constrictus, Harv.), turgid, containing tubercles immersed in mucus, and discharging their seeds by conspicuous pores. Grev.-Name, puxos a sea-weed.

* Frond flat, with a midrib.

1. F. vesiculosus, L.; frond plane, coriaceous, thick, linear, dichotomous, quite entire at the margin, midribbed; air-vessels globose, mostly in pairs; receptacles elliptical, terminal. Hook. Br. Fl. ii. p. 267; E. Bot. t. 1066; Grev. Crypt. t. 319; Wyatt, Alg. Danm. No. 152.-ß, balticus; very small, densely tufted, with an indistinct midrib, and destitute of vesicles or receptacles. F. balticus, Ag.; Grev. Crypt. t. 181.

Rocky shores, most abundant. ẞ in salt marshes, occasionally flooded by the sea, chiefly on the western shores of Scotland.--Very variable in size and general appearance, often destitute of air-vessels. B is a remarkable state, 1 or 2 inches high, scarcely a line wide, and of a tawny yellow colour, forming dense masses. This plant is extensively used in the manufacture of kelp, and furnishes besides excellent winter food for the cattle in the western islands of Scotland. See Lightfoot, Fl. Scot. vol. ii. p. 906.

2. F. ceranoides, L.; frond plane, coriaceo-membranaceous, linear, subdichotomous, entire at the margin, midribbed, without vesicles; lateral branches alternate, dichotomous, multifid, level-topped; receptacles subcylindrical, acuminated. Grev. Alg. Brit. p. 14; Hook. Br. Fl. ii. p. 267; E. Bot. t. 2115; Wyatt, Alg. Danm. No. 153.

Sea-shores, less common than the last. Perennial.-Spring and summer. Nearly related to the last species, but "it is far less tough, much thinner and more transparent in every part, both in the growing and the dried state. The midrib is finer and more clearly defined.”—Grev.

3. F. serratus, L.; frond plane, coriaceous, linear, dichotomous, serrated, midribbed, without air-vessels; receptacles flat, solitary, terminating the branches, serrated. Grev. Alg. Brit. p. 15; Hook. Br. Fl. ii. p. 267; E. Bot. t. 1221; Wyatt, Alg. Danm. No. 2.

Rocky sea-shores, very common. Perennial. Spring and summer.Frond 2-6 feet long, very variable in breadth, dark olive-green. This is sometimes used in the manufacture of kelp, but rarely, as it is far less productive than F. vesiculosus. It however forms excellent manure, and in Norway it is used, mixed with meal, as provender for cattle.

** Frond flat or compressed, without a midrib.

4. F. nodosus, L.; frond compressed, coriaceous, sub-di chotomous; branches linear, somewhat pinnated, attenuated at base, remotely denticulate, here and there swelling into oblong air-vessels; receptacles lateral, globose, stalked, springing from the axils of the serratures. Grev. Alg. Brit. p. 16; Hook. Br. Fl. ii. p. 268; E. Bot. t. 570; Wyatt, Alg. Danm. No. 154.

Sea-shores, very common. Perennial. Winter and spring.—Root a large, hard, conical mass, from which spring several fronds 2-4 or even 6 feet long, which are once or twice forked, and irregularly pinnated with alternate simple branches. Vesicles large. Substance extremely tough and leathery. Colour full olive-green, glossy.

5. F. Mackaii, Turn.; frond coriaceous, cylindrical, or subcompressed, linear, dichotomous, the apices blunt; airvessels elliptical, solitary, often wanting. Grev. Alg. Brit. p. 17; Hook. Br. Fl. ii. p. 268; E. Bot. t. 1927.

Sea-shores. Perennial. Cunnemara, Ireland, J. T. Mackay, Esq. West shores of Scotland and the Hebrides, Messrs Borrer and Hooker.Frond 6-10 inches long, densely tufted, branches crowded, spreading, compressed at base, cylindrical upwards. Vesicles wider than the frond. Receptacles unknown. Substance leathery, when dry somewhat horny. Colour dull olive-green.

6. F. canaliculatus, L.; frond coriaceous, linear, channelled on one side, dichotomous, without air-vessels; receptacles terminal, oblong-wedge-shaped, swollen, bipartite. Grev. Alg. Brit. p. 18; Hook. Br. Fl. ii. p. 268; E. Bot. t. 823; Wyatt, Alg. Danm. No. 102.

Rocky coasts, near high-water mark. Perennial. Summer and autumn. -Frond 2-6 inches high, densely tufted, several times dichotomous, of an olive-brown or yellowish colour.

*** Frond cylindrical. Root accompanied by creeping fibres.

7. F. tuberculatus, Huds.; frond cylindrical, dichotomous, the axils rounded; air-vessels rarely present; receptacles terminal, elongate, cylindrical; root accompanied by creeping processes. Grev. Alg. Brit. p. 18; Hook. Br. Fl. ii. p. 269; E. Bot. t. 726; Wyatt, Alg. Danm. No. 103.

In the sea, rather rare.

Perennial. Summer and autumn. Southern