AbstractThe development of alar cells inDrepanocladus aduncusandD. exannulatusfollows quite different paths. The type of development found inD. aduncusis also found inD. sendtneri, D. capillifoliusand, in a somewhat modified form, inD. uncinatus, D. lycopodioides, D. brevifolius, Scorpidium turgescensandCalliergon trifarium.TheDrepanocladus exannulatustype was found in the N. EuropeanCalliergonspecies (exceptC. trifarium), inDrepanocladus tundrae, D. fluitans(incl.D. h-schulzei),D. exannulatusvar.procerus, D. trichophyllusandD. badius.Outside theCalliergon-Scorpidium-Drepanocladus-complex of species types of development like that inDrepanocladus aduncusseem to be the most frequent though other quite different kinds do occur.