The "Bewildering Brush"

  FHL Marine Botany  ::::::::::::::::::::::::::::::   Taxonomy | Habitat | Morphology | Life History | Ecology | In + Around



On the four Odonthalia species of the Northwest:
"Since [the species] intergrade somewhat, they can be difficult to identify." - J.R. Waaland 1977 (1)





This bewildering alga can sometimes be confused by students (me) for various species of Neorhodomela and Plocamium. Species identification often involves morphological characteristics of cystocarps (such as size, shape, and location), branch shape, and branching pattern (2). Often, Odonthalia has profuse branching at the tips and a somewhat crooked main axis (see third picture below). Members of the family Rhodomelaceae exhibit polysiphonous construction (which, however, is difficult to see with Odonthalia) and possess both ordinary branches and trichoblasts (3).

Below are several examples of morphological variation in Odonthalia.


Odonthalia floccosa
, herbarium specimen.
Cattle Point, Andrew C. Peterson, 4/26/1989. Picture width ~3cm.


Odonthalia sp. at Botany Beach. ~18cm height.


Odonthalia sp.
at Botanical Beach. ~16 cm height.


Odonthalia sp.,
possibly Odonthalia floccosa by herbarium specimen match. ~5cm height.



1) Waaland, J. Robert. Common Seaweeds of the Pacific Coast. Seattle: Pacific Search Press, 1977.

2) Gabrielson, Paul W., Widdowson, Thomas B., and Lindstrom, Sandra C. Keys to the Seaweeds and Sea grasses of Southeast Alaska, British Columbia, Washington and Oregon. July 2006.

3) Lee, Robert Edward. Phycology. 2nd ed. Cambridge: Cambridge University Press, 1989.

    Website created by Audrey Djunaedi in May 2009 as the final project for Biol 445 Marine Botany, Friday Harbor Laboratories, University of Washington. All images created by the author unless noted otherwise. Photo permission/questions may be directed to auddju "-at-" u.