Fasciation in cockscomb celosia

Herrick Brown, curator of U S C’s A C Moore Herbarium, was with us recently to talk about fasciation – a spontaneous or damage related change in the growth of a plant. The growth tip instead of just elongating naturally for some reason splits and flattens resulting in a strange and often intriguing natural structure. You may not have seen the results of it on woody plants, but I bet you know about cockscomb celosia – in this case the fasciation trait is reliably carried in the seeds. Cactus plants also seem to spontaneously develop this peculiar growth habit – there are cactus aficionados who will give a king’s ransom for small specimens with this bizarre appearance. If people could figure out how to cause fasciation they would be thrilled but as far as I can tell how and why it occurs seems to be a headscratcher.