As for invasive bulbous or rhizomatous perennials, be aware of African cornflag (Chasmanthe floribunda), yellow flag iris (Iris pseudacorus), bulbil Watsonia (Watsonia meriana), and calla lily ...
'Dready' is a clump-forming, bulbous perennial, to around 40cm tall, with reed-like, hollow leaves. In late spring and summer, dense clusters of small, dark red bulbils are produced at the top of ...