Zostera muelleri Irmisch ex Asch.

Rhizome slightly compressed, 1–2 mm. diam.; internodes c. 1–2 cm. long. Lf-sheath 2–4 cm. long, fibrous in age, the broad, membr. margins inflexed and each terminating in an erect rounded auricle; lamina 5–30 cm. × 1–2 mm.; primary nerves 3, interstitial nerves (4)–5–(6), cross veins us. at ± regular, rather long intervals and nearly all extending from median to marginal nerve, producing a pattern of long oblongs. Erect stems narrow and flattened, the subfloral ("peduncular") internode 1–6 cm. × 0.5–1 mm. Spathe-like sheath 1.5–2.5 cm. × 2–2.5 mm. (folded width), its margins squarely truncate at the top and its terminating lamina 3–8 cm. × 1.5–2 mm. Spadix often shorter than spathe; retinacula us. 3 on each side, broadly obliquely ovate, c. 1–1.5 × 1 mm. and 2–2.5 mm. apart. Stamens and carpels closely packed, carpels rarely > 6 and anther-sacs about twice their number, all sloping obliquely inwards and upwards. Achene elliptic-oblong, c. 2.5 × 1 mm.; seed smooth, yellow. 2n = 24.

Occurs in shallow sheltered bays and inlets, on mud and sand,often exposed during low tide.