An abnormal type of secondary growth is called anomalous secondary growth. (i) In which plants it occur ? (ii) How does it occur ?
(i) It occurs in some arborescent monocots (e.g., Dracaena, Yucca, Agave) and storage roots (e.g., Beet, sweet potato).
(ii) In arborescent monocot stems, a secondary cambium grows in hypodermal region.
It later forms conjunctive tissue and patches of meristematic cells. The meristematic patches grow into secondary vascular bundles. Anomalous vascular bundles also occur in cortex (e.g., Ngctanthes) and pith (e.g., Boerhavia). In storage roots (e.g., Beet), accessory cambial rings appear on the outside of endodermis. They produce less secondary xylem but more secondary phloem.