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666 University of California Publications in Botany [Vol. 8
probably to be referred to f. typicus, but it is desirable to consult other
specimens of the distribution before deciding definitely.
This form is abundant on the California coast, but less common
toward the north, being supplanted by numerous other forms. It
reaches its optimum growth in localities where the surf is only mod-
erately active. In such situations it attains its greatest height, not
infrequently specimens attaining a height of 4.5 dm., but when on
boulders exposed to a heavy surf, it remains much shorter, is more
arborescent, the alae wearing away up to the last segment. The
illustration on Gardner's plate 3 is of the former state, and that on
plate 2 is from an exposed situation at Fort Ross, California, pre-
sumably the type locality for the species.
2. Fucus furcatus f. luxurians Gardner
Plate 99
Fronds cartilaginous, distinctly caulescent, the alae wearing away,
the much thickened midrib becoming the flattened stipe, regularly
dichotomous, 4-5 dm. (up to 9 dm.) high, dark olive green to olive
brown, midrib and receptacles yellowish, holdfast large and firm
segments varying from broadly cuneate to nearly linear, frequently
splitting obliquely to the midrib, 1.5-3 cm. wide, terminal often wider
and rounded, caecostomata very numerous, 300-350 per sq. cm.,
cryptostomata scattered, bearing fascicles of long exserted paraphyses.
Receptacles definitely delimited, 4-6 cm. long, complanate or decidedly
tumid, bi- tri-furcate, apices blunt or acuminate ; conceptacles very
numerous.
Growing on boulders and rock ledges in the middle of the littoral
belt. Northern and central California.
Gardner, Genus Fucus, 1922, p. 22, pi. 10.
Plate 99 represents a plant of this form in mature fruit, producing
receptacles for the first time. The receptacles in this specimen are
all complanate, a condition which prevails very commonly, but in
certain localities the receptacles are tumid and mucilaginous.
Forma luxurians is closely related to forma typicus. The two forms
often grow intermingled, but may readily be distinguished by differ-
ences in size and color, forma luxurians being the more robust, and of
a lighter brownish or yellowish color in the upper parts, particularly
the receptacles. The southern limit of the form, as of all forms of
;