E-Flora BC: Electronic Atlas of the Flora of British Columbia

Family Description:
Members of this family have a single, terminal blade that is divided in some species. The stipe is rarely branched. Blades are smooth or undulate, entire or with holes, of uniform thickness or with a central, thickened region (midrib). Sori develop directly on the blades.

Species description:
Split Kelp is a very dark brown species with a rather small but highly branched holdfast. Its distinctive blade (up to 2 m or 79 inches long and 40 cm or 16 inches wide), which is often flat and smooth, frequently splits longitudinally into two or three segments. There is no midrib, and the base of the blade is broadly rounded to heart-shaped. The stipe, which is up to 60 cm (24 in) long and perhaps 15 mm (about 0.6 in) in diameter, is unbranched and flattened just below the blade. Internally, the stipe contains rather large "empty" cells called mucilage ducts that form in the second year of growth. The presence of these ducts can be used to help distinguish this species from Sugar Kelp, although young plants remain difficult to identify with certainty.

Sporophytes are perennial. Sporangia are produced in indistinct patches on both surfaces of the blade, which can be smooth or densely bullate.

Split Kelp occurs both on the outer coast and in more protected waters, but seems to prefer somewhat sheltered locations. It has been reported to grow optimally at 10°C (50°F).

This species was formerly called Laminaria groenlandica in our area, but true L. groenlandica (from Greenland) is thought to be a form of L. saccharina. Phycologists are still debating about what to call this species.