Sargassum rasta R.R.M.Dixon & Huisman

Scientific Description

Habit and structure. Thallus medium or dark brown, to 17 cm tall, arising from a crustose or occasionally lobed holdfast 7–16 mm wide. Primary branches 5–16, resembling Rastafarian dreadlocks arising clustered together directly from the base, terete, 45–160 mm long, 0.75–1.00 mm diam. Primary laterals subterete, clavate, broader near the apex, tapering toward the base, densely clustered, obscuring the view of the axes beneath, 2–6 mm long, 0.2–0.6 mm wide. Secondary branches determinate, 5–52 mm long, 0.75–1.00 mm diam., dense, terete, linear or clavate, curling inwards at the apex. Vesicles, when present, densely clustered in upper branches, elliptical to elongate, with thick compressed or subterete pedicels, 1.5–2.5 mm long, 1.0–1.5 mm diam., usually with a short mucro. Fertile plants not seen.

Distribution. Widespread in northern W.A.

Habitat. Epilithic in the intertidal and shallow subtidal.

[After Dixon & Huisman, Algae of Australia: Mar. Benthic Algae of North-western Australia, 1. Green and Brown Algae 266 (2015)]