Family Description:
Most members of this family are flattened blades; they can have single, entire blades or be much-branched. The blades can be smooth or covered with short protuberances called papillae. Like other red algae, the characters that unite this family are details of the female reproductive apparatus and post-fertilization development. Tetrasporangia are cruciate and occur in internal sori.
Although members of this family have an alternation of isomorphic generations, the two generations have different cell wall carbohydrates. When extracted, the carbohydrates of the gametophyte form a gel whereas those of the tetrasporophyte form a viscous liquid. These carbohydrates represent two different forms of carrageenan, an additive to most ice creams to keep them smooth, and to chocolate milk to keep the chocolate in suspension.

Species description:
The blades of this species are reddish brown, but turn lighter in color when they become dry during an extended low tide. They are not iridescent. The blades usually measure up to 15 cm (6 in) tall by 15 cm wide, but sometimes reach a much larger size. The blades are widest above the middle, and are deeply cleft into irregular lobes (except male gametophytes, which are entire). The blades either taper to a short stipe at the base, or they can be sessile on the surface of the holdfast with no intervening stipe.

The cystocarps in this species are especially large; they measure up to 4 mm (almost 0.2 in) in diameter and bulge from both surfaces of the mature blades.

The Northern Mazza Weed grows only on rock. It is generally more common in Alaska than the following species, which dominates low intertidal-upper subtidal shores in southern British Columbia and northern Washington.

Source:  North Pacific Seaweeds

Synonyms and Alternate Names:
Mazzaella heterocarpa