Plumularia meretricia  

P. meretricia, shows considerable variability of features usually regarded as reliable specific criteria among the Plumulariidae. The younger stems have a smooth glassy appearance, with long stem and hydrocladial internodes, and also have cauline nematothecae. The stems seldom retain their cauline nematothecae after maturity, showing only scars where the nematothecae have dropped off. Since many of the younger stems show neither scars nor nematothecae, and in some cases, the axillar nematothecae have failed to develop as well, the presence or absence of these structures cannot be regarded as diagnostic of the species. The mamilliform pore is however, a constant feature of all the stems. The regenerated athecate hydrocladial internodes common in some stems, mark the site of repeated breakage and regrowth of the hydrocladium. In these cases, a short athecate internode is first added, followed by an embryonic hydrotheca and infrathecal chamber. Nematothecae bud off later as the hydrotheca nears maturity. The athecate internode at this stage is without internal perisarcal ridges. These develop as the hydrocladium ages.