Question

Anomalous secondary growth occurs in

• A. Only monocots
• B. Only dicots
• C. Both monocots and dicots
• D. All plants

Answer 1

The correct option is C Both monocots and dicots

Abnormal secondary growth does not follow the pattern of a single vascular cambium producing xylem to the inside and phloem to the outside as in ancestral lignophytes. Some dicots have anomalous secondary growth, e.g. in Bougainvillea a series of cambia arise outside the oldest phloem. Ancestral monocots lost their secondary growth and their stele has changed in a way it could not be recovered without major changes that are very unlikely to occur. Monocots either have no secondary growth, as is the ancestral case, or they have an anomalous secondary growth of some type, or, in the case of palms, they enlarge their diameter in what is called a sort of secondary growth or not depending on the definition given to the term. Palm trees increase their trunk diameter due to division and enlargement of parenchyma cells, because there is no production of secondary xylem and phloem tissues. So, option C is correct.