What is "sea lettuce"

Sea lettuce \Sea" let"tuce\ (Bot.) The green papery fronds of several seaweeds of the genus Ulva, sometimes used as food.

Lettuce \Let"tuce\ (l[e^]t"t[i^]s), n. [OE. letuce, prob. through Old French from some Late Latin derivative of L. lactuca lettuce, which, according to Varro, is fr. lac, lactis, milk, on account of the milky white juice which flows from it when it is cut: cf. F. laitue. Cf. Lacteal, Lactucic.]

1. (Bot.) A composite plant of the genus Lactuca ( Lactuca sativa), the leaves of which are used as salad. Plants of this genus yield a milky juice, from which lactucarium is obtained. The commonest wild lettuce of the United States is Lactuca Canadensis.

2. United States currency; dollar bills; greenbacks. [slang]

   Hare's lettuce, Lamb's lettuce. See under Hare, and Lamb.

   Lettuce opium. See Lactucarium.

   Sea lettuce, certain papery green seaweeds of the genus Ulva.

n. 1 Any of several edible seaweeds of the genus ''Ulva''. 2 Similar seaweed species of other genera: 3 # (taxlink Monostroma genus noshow=1), also known as the (vern: slender sea lettuce), a genus of algae. 4 (taxlink Scaevola taccada species noshow=1), also known as the (vern: beach cabbage), a terrestrial flowering plant species that is native to coastal regions of the Indo-Pacific. 5 (taxlink Dudleya caespitosa species noshow=1), also known as the (vern: sand lettuce), a terrestrial flowering plant species that is endemic to coastal areas of California

n. seaweed with edible translucent crinkly green fronds [syn: laver]

The sea lettuces comprise the genus Ulva, a group of edible green algae that is widely distributed along the coasts of the world's oceans. The type species within the genus Ulva is Ulva lactuca, lactuca being Latin for "lettuce". The genus also includes the species previously classified under the genus Enteromorpha, the former members of which are known under the common name green nori.