<P> 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 , which is termed `` primary gigantism '' because there is no production of secondary xylem and phloem tissues , or sometimes `` diffuse secondary growth '' . In some other monocot stems as in Yucca and Dracena with anomalous secondary growth , a cambium forms , but it produces vascular bundles and parenchyma internally and just parenchyma externally . Some monocot stems increase in diameter due to the activity of a primary thickening meristem , which is derived from the apical meristem . </P>
<P> 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 , which is termed `` primary gigantism '' because there is no production of secondary xylem and phloem tissues , or sometimes `` diffuse secondary growth '' . In some other monocot stems as in Yucca and Dracena with anomalous secondary growth , a cambium forms , but it produces vascular bundles and parenchyma internally and just parenchyma externally . Some monocot stems increase in diameter due to the activity of a primary thickening meristem , which is derived from the apical meristem . </P>
an example of monocot showing secondary growth in stem is
an example of monocot showing secondary growth in stem is
Yucca
Yucca