SUMMARYErythrocladia subintegrahas been cultured for over 3 years. The life history includes reproduction by monospores, a long period of ameboid motility by monospores, their germination and growth into monostromatic disk‐shaped plantlets composed of adherent, often dichotomously branched filaments. Plants become centrally polystromatic with age and produce monospores. Variations in plant size and shape, cell size and shape, spore size, shape, and motility are discussed. Variations in plants ofE. subintegragrown on different substrates have been studied and discussed in relation to other species in the genu