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Kingdom: Plantae
Division: Chlorophyta
Class: Ulvophyceae
Order: Ulvales
Family: Ulvellaceae
Genus: Ulva
Species: U. angusta - U. californica - U. costata - U. dactylifera - U. expansa - U. lactuca - U. lobata - U. rigida - U. stenophyll - U. taeniata


Commonly know as Sea Lettuce.


Mature thallus forms a flattened blade which can be broadly expanded, irregularly lobed, and linear. Usually attached to substrate by rhizoidal cells in a basal holdfast and/or rhizoidal extensions of cells in the lower portion of the blade. Vegetative reproduction by fragmentation or by growth of new upright thalli from basal cells and/or persistant holdfasts. Species of Ulva have traditionally been based on morphological, anatomical and cytological characteristics such as shape, size, presence or absence of dentation, thickness, cell dimensions and number of pyrenoids. Many studies have shown that these characteristics can be highly variable within species, varying with age, reproductive state, wave exposure, tidal factors, temperature, salinity, light and biological factors such as grazing.[1]


The Ulva genus is divided into 121[1], with the more common ones being:




  1. 1.0 1.1 (http://www.algaebase.org): Guiry, M.D., Guiry, G.M, Algae Base, National University of Ireland, Galway, 2007, Retrieved: 20 February 2008.