Family Description:
Tetrasporangia are intercalary and cruciately divided. The carpogonial branch is usually four cells long.

Species description:
A usually undivided blade up to about 60 cm (24 in) long and up to 20 cm (8 in) wide tapers rapidly to a stipe of variable length attached to a small discoidal holdfast. When vigorously growing, the blade is rose red, although later it bleaches out to yellowish, especially near the top. The distinctive feature of Red Eyelet Silk is that it is perforated with numerous small, natural holes (in a manner reminiscent of the brown alga, Sieve Kelp). These holes make Red Eyelet Silk easy to identify, but they can be lacking in very young blades. The holes might be caused by a fungal infection.

Short (less than 1 cm or 0.5 in tall) stipelike protrusions at the base of a blade are the indications of a new generation of blades.

Gametophytes are dioecious, so male and female gametophytes are separate organisms. At times the blade can be covered with bumps; these bumps contain the carposporophytic generation. The life history, which has all three phases, is isomorphic (in other words, gametophytes are indistinguishable from tetrasporophytes).

Individuals collected from southern British Columbia/northern Washington withstood a week of immersion in water at a temperature of 18°C (64°F) but died when placed in warmer water.

Red Eyelet Silk is common to almost abundant at exposed places on the outer coast. In more protected waters, it is much less frequent, at least intertidally. This is certainly one of our loveliest algae, and well worth the search to find it.

Source:  North Pacific Seaweeds

Synonyms and Alternate Names:
Porphyra pertusa
Rhodymenia pertusa
Rhodymenia stipitata