Ulva lactuca Linnaeus, a green alga in the Division Chlorophyta, is the type species of the genus Ulva, also known by the common name sea lettuce.
is a thin flat green alga growing from a discoid holdfast
. The margin is somewhat ruffled and often torn. It may reach 18 cm
or more in length, though generally much less, and up to 30 cm
across. The membrane is two cells thick, soft and translucent. and grows attached, without a stipe
, to rock by a small disc-shaped holdfast
. Green to dark green in color this species in the Chlorophyta is formed of two layers of cells
irregularly arranged, as seen in cross section. The chloroplast
is cup-shaped with 1 to 3 pyrenoids
. There are other species of Ulva
which are similar and not always easy to differentiate.
The distribution is worldwide: Europe
, North America - west and east coasts, Central America
Islands, South America, Africa
, Indian Ocean Islands, South-west Asia, China
, Pacific Islands, Australia
, and New Zealand.
is very common on rocks and on other algae in the littoral
on shores all around the British Isles
. It is particularly prolific in areas where nutrients are abundant.
The sporangial and gametangial thalli are morphologically alike. The diploid
adult plant produces haploid
spores by meiosis
, these settle and grow to form haploid male and female plants similar to the diploid plants. When these haploid plants release gametes
they unite to produce the zygote
which germinates, and grows to produce the diploid plant.
U. lactuca is locally used in Scotland in soups and salads.
- Hayden, H.S., Blomster, J., Maggs, C.A., Silva, P.C., Stanhope, M.J. and Waaland, J.R. (2003) Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera Eur. J. Phycol. 38, 277-294.