Identifying running from clumping bamboo

I have recently noticed both on E-bay and the Trading Post some either dishonest or unwitting advertisers selling running bamboo as non-invasive clumping bamboo, as most running varieties of bamboo being sold are from the phyllostachys species identification is easy.There is a flat section on the culm (cane or stem) on alternate sides between the branches called a sulcus, the branch sets usually contain two or three branches. In contrast clumping bamboo do not have a flat spot they are round between the nodes and have multiple branches and leaves. Non-invasive clumping bamboo is gaining recognition now as a predictable and beautiful landscape plant that is well deserved and we don't need misinformed or unscrupolous people spoiling that.