Dictypoteris plagiogramma
Phaeophyta, Dictyotaceae
Authority: (Montagne) Vickers
Hawaiian name: limu lipoa ('gathered from the deep')
Characteristic feature: Brown alga forming Y branches with a distinct midrib.
Description: Plants erect, 15-32 cm tall from conical or irregular holdfast supporting one to several fronds; yellowish brown to darker brown, thin and flat, occasionally twisted, with prominent midrib, margins planar or ruffled; fine veinlets run from near midrib to margins, forming repeating V pattern; dark hair tufts mostly in single row along each side of midrib on both frond surfaces, or irregular or absent, never forming a repeating pattern; fronds mostly dichotomous; margins of lower parts of older fronds sometimes abraded, leaving only thickened midrib. Sporangia isolated or in samll, oval sori, initially forming along both sides of midrib on one or both frond surfaces, 90-120 µm diameter in surface view, spreading slightly when mature.
Habitat: Low intertidal to at least 80 m. Usually growing on rocks, occasionally epiphytic on Sargassum spp. Sometimes growing in dense beds at depths greater than 8 m; has been dredged from 30-80 m depth. Uncommon on reef flats and shallow subtidal.
Hawaiian distribution: All main Hawaiian Islands, including the Northwestern Hawaiian Islands.
Other: Among the most favoured of limu eaten by Hawaiians. Has a characteristic aroma and unique spicy flavour. Plants lose the brown coloring and turn greenish after being collected or washed on-shore.
Dictyopteris australis, a similar species, has parallel rows of dark hair tufts running downward from the midrib to margin.