sentences:  Lycopods and sphenopsids got a fair way down the path to the seed habit without ever crossing the threshold.Fossil lycopod megaspores reaching 1 cm in diameter, and surrounded by vegetative tissue, are known (Lepidocarpon, Achlamydocarpon);– these even germinated into a megagametophyte "in situ".However, they fell short of being ovules, since the nucellus, an inner spore-covering layer, does not completely enclose the spore.