Name: Ascophyllum nodosum, (Linnaeus) Le Jolis – Knotted Wrack
Family: Fucaceae
Collection Date: 15 September 2011
Location: Nantasket Beach, Massachusetts
Collector: Dr. Matthew Hils
Key Used: Taylor, W. R. (1957). Marine Algae of the Northeastern Coast of North America . Ann Arbor : The University of Michigan .
Key to the Orders of the Marine Algae
1. Chlorophyll masked by accessory pigments … 3
3. Accessory pigments imparting a brown color; reproduction at some stage typically involving flagellate cells … 10
10. If filamentous, not polysiphonous, though often pluriseriate … 12
12. Massive, cylindrical, or phylloid, or slender but pluriseriate, or reduced types … 13
13. Filamentous structure lacking, obscured, or only shown in evanescent plant parts…14
14. Sporophyte lacking free assimilators … 15
15. Gametophyte reduced to cytological phases; sporophyte massive and branched … Fucales p. 188
Key to Families
1. Axes subterete, to alate with a midrib, but not foliar; vesicles if present intercalary … Fucaceae, p. 189
Key to Genera
1. Branches at most compressed, but not differentiated into midrib and blade … Ascophyllum, p. 195
Key to Species
1. Plants erect, axes distinct, vesicles present; receptacles oval, short … A. nodosum, p. 195
Description:
“Ascophyllum nodosum has long fronds with large egg-shaped air-bladders set in series at regular intervals in the fronds and not stalked. The fronds can reach 2 m in length and are attached by a holdfast to rocks and boulders. The fronds are olive-brown in color and somewhat compressed but without a mid-rib.” (Taylor, 1957)
Figure 1: Up close of A. nodosum
Links:
References:
S. Hiscock (1979). "A field key to the British brown seaweeds (Heterokontophyta)". Field Studies 5: 1–44.
Taylor, W. R. (1957). Marine Algae of the Northeastern Coast of North America . Ann Arbor : The University of Michigan .
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