Download PDF

1925] Setchell-Gardner: Melanophyceae 679
Growing on rock ledges exposed to the action of the surf, in the
upper third of the littoral belt. Cape Arago, at the entrance to Coos
Bay, Oregon.
Gardner, Genus Fucus, 1922, p. 28, pi. 21.
This form grew in abundance in company with F. furcatus f.
angustus. The two groups of plants were, however, in slightly differ-
ent altitudes in the belt, and were not indiscriminately intermixed.
When the two sets of plants are dried, they are easily distinguishable
by the smoothness of the segments, forma hesperius being smooth
and usually shining, while forma angustus is rough, due to caecosto-
mata, and is of a duller color.
2. Fucus edentatus f. divergens Gardner
Fronds coriaceous, smooth and glossy, 28-38 cm. high, regularly
dichotomous, dark olive green, black on drying; segments divergent,
7-11 mm. (up to 15 mm.) wide, cuneate below, linear above, reduced
somewhat above each forking, terminal truncate, growing point incon-
spicuous, midrib very distinct, percurrent, cryptostomata and caeco-
stomata absent or very sparse ; receptacles 3-6 cm. (up to 12 cm.) long,
definitely delimited, much wider than the segments, single or bifurcate,
and mostly widely divergent, apices acuminate or acute ;
numerous and prominent.
conceptacles
Growing on rock ledges in the lower littoral belt. Kanaka Bay,
San Juan Island, Washington.
Gardner, Genus Fucus, 1922, p. 29, pi. 22.
This form of edentatus is closely related to forma hesperius. The
fronds average somewhat wider, more robust, the angles between the
segments are very much wider and more rounded, and the receptacles
mostly deeply bifurcate or single, widely diverging. The average
width of the segments is about 10 mm., but a few specimens were
found with extremely narrow segments, about 3 mm. These were
profusely branched, with wide angles, and small diverging receptacles.
Also a few specimens were found with the characters of the form, but
were 15 mm. wide. These few specimens are to be considered as the
extremes in individual variation in this particular character.