purslane

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A trailing plant (Portulaca oleracea) native to Eurasia, having small yellow flowers, reddish stems, and fleshy obovate leaves that can be cooked as a vegetable or used in salads.

from The Century Dictionary.

• noun A herbaceous plant, Portulaca oleracea, widely distributed through warm and temperate climates.
• noun In America, Sesuvium Portulacastrum, of the warmer Atlantic shores and the saline or alkaline valleys of the southwestern United States, a prostrate fleshy plant, forming mats sometimes 6 feet broad; also, S. pentandrum, sometimes erect, reaching north to New Jersey.
• noun Ludwigia palustris.
• noun An American aquatic or sometimes terrestrial herb, Didiplis linearis, of the Lythrarieæ, with opposite linear leaves and very small greenish flowers.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) An annual plant (Portulaca oleracea), with fleshy, succulent, obovate leaves, sometimes used as a pot herb and for salads, garnishing, and pickling.
• noun the Portulaca grandiflora. See Portulaca.
• noun a South African shrub (Portulacaria Afra) with many small opposite fleshy obovate leaves.
• noun a seashore plant (Arenaria peploides) with crowded opposite fleshy leaves.
• noun an aquatic plant (Ludwiqia palustris) but slightly resembling purslane.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A widely-grown edible plant, Portulaca oleracea in the family Portulacaceae.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a plant of the family Portulacaceae having fleshy succulent obovate leaves often grown as a potherb or salad herb; a weed in some areas