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572 University of California Publications in Botany [Vol. 8
Agardh, Syn. Alg. Scand., 1817, p. xii and p. 12, Jim. mut.;
Greville, Alg. Brit., 1830, p. 44.
The name Chord aria was first proposed by Link in 1809 to include
a series of different plants, none of which, however, belong to this
entity as now constituted. C. Agardh (1817, p. xii) modified the
limits of the genus to include C. rotunda, C. divaricata, C. flagelli-
formis, C. cabrera, and C. Filum and three other doubtful species. Of
these C. flageUiformis is the only northern species of the series now
generally included under the genus, but some authors also include
C. divaricata, Greville (1830, p. 44, pi. 7) was the first definitely to
establish the present limits of the genus by pointing out a type, viz.,
C. flageUiformis.
Key to the Species
1. Fronds flagelliform, cylindrical throughout 2
1 Fronds irregular in diameter, flattened at the branching .3. C. dissessa (p. 574)
2. Fronds relatively robust, up to 9 dm. high, usually with many long,
slender, primary branches 1. C. flageUiformis (p. 572)
2. Fronds slender, up to 3.5 dm. high, primary branches patent, scattered
along the whole main axis up to 4 cm. long 2. C. gracilis (p. 573)
1. Chordaria flageUiformis (Muell.) Ag.
Fronds attached by a small disk, solitary or in groups, lubricous,
solid, 2-5 dm. (up to 9 dm.) long, branching close to the base into
many branches of nearly equal length, or the main axis percurrent
giving rise to numerous alternate branches, shorter above; branches
usually of 3 orders; peripheral assimilating filaments 6-8 cells long,
with terminal cell nearly spherical, and with numerous hyaline hairs
interspersed ; color dark olive brown, nearly black ; zoosporangia ovoid
to pyriform, arising at the base of the cortical filaments.
Growing on rocks in the upper sublittoral belt.
Agardh, Syn. Alg. Scand., 1817, p. 12 and p. xii. Fucus flageUi-
formis Mueller, Flor. Dan., 1771, pi. 650.
This species in its various forms seems to be exclusively boreal,
though extending much farther south on the Atlantic shore than on
the Pacific shore of North America. It is very common on the
American and European shores of the North Atlantic. It has been
reported as far north as the Spitsbergen Islands and in the Baltic
Sea. The following forms have been reported within our territory.