Definitions

gametangial

Ulva lactuca

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.

Description

Ulva lactuca 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.

Distribution

The distribution is worldwide: Europe, North America - west and east coasts, Central America, Caribbean Islands, South America, Africa, Indian Ocean Islands, South-west Asia, China, Pacific Islands, Australia , and New Zealand.

Ecology

Ulva lactuca is very common on rocks and on other algae in the littoral and sublittoral on shores all around the British Isles. It is particularly prolific in areas where nutrients are abundant.

Life history

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.

Uses

U. lactuca is locally used in Scotland in soups and salads.

References

Further reading

External links

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