Home / Rhodophyceae / Macroreds / Dumontia
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Name derivation:
Dumontia = Named for Georges Louis Marie Dumont de Courset, a French botanist and horticulturist contorta= L. contortus: twisted, entangled common names: worm weed or Dumont’s weed
Classification:
Dumontia J.V.Lamouroux 1813; 3 of 33 species descriptions are currently accepted taxonomically (Guiry and Guiry 2014).
Morphology:
algae have erect fronds, 10-25 (-60) cm tall, with tendril-like axes, usually clustered, dull red or dull yellow when old, and attached by a shield-shaped holdfast. Erect axes degenerate during summer and crustose bases regenerate next spring. Axes are twisted or contorted, simple or often irregularly-alternately (1-2 times) branched, solid near bases and young branches, while older axes are hollow, inflated or compressed, and 12 -26 mm in diam. Medulla has loose filaments in mucilage with outer ones producing short radial rows of cortical cells. Tetrasporangia cruciate; gametophytes are dioecious.
Similar genera:
Cystoclonium purpureum is superficially similar but has different anatomical features.
Habitat:
An introduced very common species, particularly during winter-late spring annual, eroding to perennial axes in the fall. On rocks in tide pools and to 10 m, and with a variable morphology.
References:
Guiry, M.D., and G.M. Guiry 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 16 January 2013. Kilar, J. A. and A. C. Mathieson. 1978. Ecological studies of the annual red alga Dumontia incrassata (O. F. Müller) Lamouroux. Bot. Mar. 21: 423-437. Taylor, W. R. 1957. Marine Algae of the Northeastern Coast of North America. Revised edition. Univ. Michigan Press., Ann Arbor, ix + 509 pp.( as D. incrassata)