The preface to the info I offered, that "they're all Portulacas" was intended to make the use of the abbreviated P. obvious that I was referring to Portulaca each time. That is what I meant because purslane isn't a genus.
And yes, common names can connect to a genus, specific species, or not. Overlap is very common with common names, and confusion can arise when a specific ID has not yet been established in the discussion by use of a botanical epithet.
purslane = Portulaca oleracea
ornamental purslane = Portulaca umbraticola
moss roses = Portulaca grandiflora
These are the ones I've seen in stores over the yrs as bedding plants. There are also many other species of Portulaca, some of which have more of a house plant reputation vs. a landscape decoration.
