Enteromorpha: now Ulva See Eur. J. Phycol. (August 2003) 38:
277-294. Linnaeus was right all along: Ulva and Enteromorpha are
not distinct species. When Enteromorpha first begins growing, it
forms a single row of cells, this structure is monosiphonous.
Soon after the monosiphonous filament is formed, longitudinal
division of cells creates a two layered filament. Eventually,
after more cell division the two cell layers separate to form a
tube, forming the adult morphology. The thallus of Enteromorpha
is tubular with the wall of the tube a single cell layer thick.
The thallus can be branched or unbranched, and there is a wide
variety of forms within the genus. Enteromorpha is attached to
the substrate by a disc-like holdfast. The holdfast is formed by
the basal cell dividing into three or four holdfast cells which
elongate and undergo further The cells in Enteromorpha can vary
in size and shape from species to species, and sometimes they
will form regular linear series in a frond, while other times
there is an