Читать книгу Pacific Seaweeds - Louis Druehl - Страница 66

66 | Cylinders

Pacific Seaweeds

Cylinders

Ulva (cylindrical form) Green string lettuce

Class Ulvophyceae Order Ulvales Family Ulvaceae

Number of Species

Ulva (Latin=marsh plant) contains a stunning 128 species and forms world-wide. Locally, it is represented by about 15 species, of which at least 7 develop a cylindrical morphology and were formerly contained in the genus Entero-morpha (Greek=intestine form). Common species in our area include: U. compressa, U. linza and U. intestinalis.

Description

Tubular species of Ulva (see p. 62 for discussion of bladed forms) have two cell layers that are separated to form a tube, like a cylindrical balloon. Ulva intestinalis is usually unbranched and cylindrical throughout, whereas U. compressa is often sparsely branched and imperfectly compressed away from the base. The tubes may reach 50 cm (20 in) in length but are usually less than 20 cm (8 in) long, and their width varies from a few millimetres to 4–5 cm (1.6–2 in). Ulva linza is tubular only at the base and looks similar to a bladed Ulva (or a deflated balloon), except that it is long, up to 45 cm (18 in), narrow, 1–4 cm (0.4–1.6 in), and distinctly ruffled.

A shaggy wig of cylindrical Ulva sp. adorns an intertidal rock.