Galactan (galactosan) is a polysaccharide consisting of polymerized galactose. In general, galactans in natural sources contain a core of galactose units connected by α(1→3) or α(1→6), with structures containing other monosaccharides as side-chains.
Galactan derived from Anogeissus latifolia is primarily α(1→6), but galactan from acacia trees is primarily α(1→3).
Halymenia durvillei is a red seaweed (algae) that produces a sulfated galactan. Several other algae species also contain galactans. Including Carpopeltis .