Overview
Ulva spp. is a genus of green seaweeds, or marine green algae, in the family Ulvaceae, called sea lettuce and found along rocky and sheltered coastlines worldwide. The body, called a thallus, is a thin translucent sheet or tube of bright green tissue only two cell layers thick, growing 4 to 12 in (10 to 30 cm) or more across and anchored to rock, shell, or other surfaces by a small holdfast rather than roots. The blade is often ruffled at the margins and has no internal veins, stem, or flowers; its color comes from chlorophyll, which gives the genus its grass-green tone. Ulva spp. grows in the intertidal zone and shallow subtidal water, tolerating a wide range of salinity from open ocean to brackish estuaries, and reproduces by releasing swimming spores and gametes into the water. The genus takes up dissolved nitrogen and phosphorus fast, and in nutrient-rich coastal water it can multiply into floating mats known as green tides that wash ashore and decay. Several species are harvested as food, eaten fresh or dried in salads and soups in coastal cuisines, and are studied as a fast-growing source of protein and for treating wastewater. Because it depends on submersion in salt or brackish water, Ulva spp. cannot be grown as a garden or container plant.
Native Range
Ulva spp. occurs on coastlines worldwide, from cold temperate to tropical seas, growing on intertidal rock, tide pools, jetties, and in estuaries. Species are found on shores across every ocean and in many brackish bays and lagoons.Suggested Uses
Ulva spp. is harvested as an edible seaweed, eaten fresh or dried in salads, soups, and seasonings along many coasts. It is grown in marine aquaria as a fast-growing algae that takes up excess nutrients, and is studied for water treatment and as a protein and biomass crop.How to Identify
Appearance
Size & Dimensions
Height4" - 1'
Bloom Information
Sea lettuces do not flower; Ulva spp. reproduces by spores and gametes released into the water. Reproduction peaks in the warmer months, when rising temperature and nutrients can trigger fast growth and floating green-tide mats. Swimming spores settle on hard surfaces to start new blades.
Detailed Descriptions
Foliage Description
bright grass-greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Water Needs