Crocosmias increase many different ways and for that reason are considered to be invasive by many. Crocosmia × crocosmiiflora has become an exotic weed in places that remain wet in California in the summer (drainage ditches, watered gardens.) As Vivien has pointed out the old corms do not shrivel away, but I believe only the top corm probably produces a flower. David Pilling has added a photo of stacked corms on the wiki. http://pacificbulbsociety.org/pbswiki/index.php/… But if you are trying to get rid of them (I'm experienced with this) and think you have gotten all of them out, you may have just pulled the top corms off and what is left is capable of blooming once the newer corm is removed. When I lived in a warmer sunnier summer location I tried to get all of them out of perennial beds when they were taking over and the next year there were still leaves and flowers. So perhaps this was one way of keeping them in hand. As Vivien also noted, the corm sends out runners in more than one direction and each runner creates new corms as it runs. The new corms probably have to get a certain size before they bloom, but I don't know how big that might be. I should have taken a photo of the runners for the wiki the last time I dug them out. In my dry and shady summer garden they don't bloom much, so I'd just have a lot of leaves and no flowers if I left them and in time more and more of them so I dig them out. And when I think they are all gone, in later years I find them again so obviously I didn't get them all. I don't know if all the species and cultivars behave in this same way. Photos on the wiki from David Pilling show some large flowering clumps. I wonder how many corms there are in that patch. Mary Sue