Plants erect, repeatedly branched, and bushy, articulated, calcified except at the nodes (genicula), with several upsights arising from conspicuous basal crusts; branching dichotomous with some irregular, basically in one plane; axial inter-genicula terete to somewhat flattened, mostly cylindrical; genicula of a single tier of long, thin, thick-walled medullary cells, cortex lacking; medulla of arching transverse tiers of similar length, elongated cells, of secondary pit connections lacking, tiers of similar length throughout; cortex few to several layers composed of small rounded cells radiating from sharply delineated medullary cells; intergenicula with conceptacles usually branched (with horns); a few tetrasporangia in expanded conceptacles formed apically on axial intergenicula, each conceptacle with a single central pore; dioecious, spermatangia formed in single-pored terminal conceptacles with deep, narrow cavities; carpogonial branches two celled, borne on supporting cells which form the basal layer of female conceptacles, later acting as auxilliary cells and fusing to form thin, narrow conceptacle fertile floors; carposporophytes borne within single-pored apical conceptacles nearly all gonimoblast cells become carposporangia.

Habitat:
Close examination of almost any habitat will reveal the presence of this seaweed.

(In: http://chrsl.chem.lsu.edu/~wwwpb/Chapman/jania.html)