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96
THE MARINE ALGÆ OF NEW ENGLAND.
common on the coast of Maine, but much less abundant than other Laminariæ. It is the most easily
recognized of our Laminariæ, in spite of its great variability in outline. The substance is more tough
and leathery than any of our other species and the margin is thick and never wavy. At Eastport it is
found in deep pools, but elsewhere it is an inhabitant of deep water. As usually seen washed ashore it
resembles one of the digitate forms of Laminaria, for it is usually torn into segments, and not rarely
split to the very base. It is at once distinguished from our digitate Laminariæ by its uniformly flat
stipe, very short root-fibers, and cryptostomata. In most cases the stipe expands very gradually into the
blade, but occasionally in old specimens the base is cordate. The fruit is found in the autumn and
winter. In the specimens which we have examined the paraphyses were very narrowly club-shaped and
colored to the tip, being destitute of the hyaline tip found in Laminaria.
AGARUM, (Bory) Post. & Rupr.
(From agar-agar, a Malayan word referring to some edible sea-weed.)
Fronds stipitate, attached by a branching root-like base; lamina perforated with
roundish holes; stipe prolonged into a midrib; fruit scattered in patches (sori) over
the fronds, consisting of club-shaped, one-celled paraphyses and ellipsoidal
unilocular sporangia; plurilocular sporangia unknown.
A genus differing from Laminaria in having the lamina perforated with round holes and furnished with
a distinct midrib. It includes four described species, which differ in the size of the perforations, in the
shape of the lamina, and the prominence of the midrib, characters which an observation of our common
species shows to be very variable The species inhabit the Arctic Ocean, the northwestern shore of the
Atlantic, and the North Pacific. The New England form, A. Turneri, also occurs in the Pacific extending
as far south as Japan, and, on the west coast, A. fimbriatum, Harv., considered by Agardh to be the
same as Fucus pertusus, Mertens, extends as far south as Santa Barbara, Cal.
A. TURNERI, Post. & Rupr.—Sea Colander. (Fucus cribrosus, Mertens.—F. agarum,
Turner, Hist. Fuc., Pl. 75.—Laminaria agarum and L. Boryi, De la Pyl., Flore de
Terre-Neuve.—Agarum Turneri, Post. & Rupr., Illustr. Alg., Pl. 22; Ner. Am. Bor.,
Vol. I, Pl. 5.)
Exs.—Algæ Am. Bor., Farlow, Anderson & Eaton, No. 112.
Base much branched, stipe two inches to a foot long, cylindrical below, flattened
above and prolonged into a distinctly marked midrib; lamina menbranaceous, one to
four feet long, ovate-oblong, cordate and much crisped at base, margin wavy;
perforations very numerous, orbicular, irregularly scattered with a smooth or wavy
margin; fruit in irregular patches in the central part of the frond; sori .05-6 mm in
thickness; paraphyses club-shaped, colored below, expanded and hyaline at the top;
sporangia narrow, ellipsoidal, .035 mm long by .012 mm broad.
Common from Nahant northward in deep water and at Eastport in pools; North
Pacific.
One of the curiosities of our marine flora, which is washed ashore from deep water at the southern limit
of its growth, but farther north grows in pools at low-water mark.