Ulva compressa L.

Scientific Description

Habit and structure. Thallus medium green, 2–20(–40) cm high, erect and basally attached, usually much branched from near the base and often from above, occasionally with few basal branches only; branches broadening above, either remaining terete and 3–10(–20) mm in diameter, or commonly becoming compressed and 0.5–3(–6) cm broad, with the cell layers adjacent but not attached and the margins remaining saccate and in some forms becoming ruffled. Cells un-ordered at least in upper stipe and lower blade, but above with mixture of un-ordered areas and patches where rows of cells have developed by localised divisions; cells polygonal to rounded, 10–14(–16) µm across, square to rectangular when in rows; chloroplast laminate, filling most of the cell in surface view, with a single pyrenoid (two in larger cells prior to division).

Reproduction. Generations isomorphic, gametophytes dioecious, anisogamous.

Distribution. Cosmopolitan.

[After Womersley, Mar. Benthic Fl. Southern Australia I: 158 (1984), as Enteromorpha compressa]