Ulva flexuosa

Rybak, Andrzej S., 2018, The Ulva flexuosa complex (Ulvaceae, Chlorophyta): an updated identification key with special reference to the freshwater and hyperhaline taxa, Phytotaxa 345 (2), pp. 83-103 : 98

Description of Ulva flexuosa

(after Bliding 1944, 1960, Pliński & Hindák 2012, Brodie et al. 2016 —with modifications): Thalli highly variable in overall morphology, up to 60 cm in length, up to 2 cm broad; its narrow tubes are less than 1 mm in diameter. Ribbons may be branched. Occasionally with opposite and lateral branching reaching same size as the main axis; axes often aggregated into mats, typically soft and flaccid in consistency, pale yellowish green; axes cylindrical, compressed, or inflated; sparsely branched up to 20 cm long, about 1–20 mm wide, terminal branchlets sometimes uniseriate; cells in distinct longitudinal and transverse rows, measuring 15–30 × 9–25 μm; the cells are typically rectangular or square but newly formed walls are oblique; chloroplast parietal, in the shape of hollow cylinder, sometimes with scalloped margins, containing 1–4(8) pyrenoids.