Portulaca oleracea has various cultivars in regard to flavor/texture. P. umbraticola is the one sold as ornamental and has MANY cultivars.
Until P. umbraticola was mistakenly introduced into commerce as "ornamental purslane," and labeled incorrectly as P. oleracea, there wasn't much confusion which plant was being discussed under the nickname "purslane." Now it's not an automatic assumption that one is referring to P. oleracea by using the name purslane. Because of this, so many people have eaten P. umbraticola, I think it would be well know, after a couple decades, to not eat that one if there was any foul flavor or difficulties with digesting it.
http://www.chicagotribune.com/...
http://chocolateandzucchini.co...