DECEPTIVE SIMILARITY. “By the same token, the arborescent growth habit of many present-day and extinct vascular plants which is achieved by virtue of secondary tissues produced by the vascular and cork cambia (e.g. Lepidodendron, Calamites and Pinus) is mimicked by monocot and fern species lacking cambia (e.g. Cocos nucifera and Cyathea medullaris).”
http://aob.oxfordjournals.org/content/85/4/411.full.pdf