Craig Wm Schneider's Seaweed Lab

L-systems computer models generating distichous from spiral organisation in the Dasyaceae (Ceramiales, Rhodophyta)


European Journal of Phycology 29: 165-170


L-systems provide a method of modeling seaweed branching patterns in terms of simple rules. These rules can be used to generate computer graphics images of an alga’s basic architecture, which, of course, is often obscured by adventitious growth in living plants. L-systems provide a mathematical abstraction that allows us to compare species by focusing on essential differences in their substitution rules rather than relying entirely on the visual appearance of branching patterns. Two species of red algae from closely related genera in the Dasyaceae, Dasya rigidula and Dasysiphonia concinna, are virtually identical in pseudolateral branching detail and appear to diverge solely in terms of pseudolateral position. L-systems models and their graphical representations are presented to demonstrate that the two-dimensional, alternate distichous pattern of pseudolateral position for D. concinna can be derived in a straightforward way from that of the three-dimensional, spiraled pattern of D. rigidula. These models illustrate a case in which generic distinction is based upon an easily observable but relatively trivial feature, differences other than branching pattern being quite subtle.

Key words: Dasya, Dasyaceae, Dasysiphonia, L-systems

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