Page "Asparagales" Paragraph 12

* Most monocots are unable to thicken their stems once they have formed, since they lack the cylindrical meristem present in other angiosperm groups.

Asparagales have a method of secondary thickening which is otherwise only found inDioscorea ( in the order Disoscoreales ).

In a process called ' anomalous secondary growth ', they are able to create new vascular bundles around which thickening growth occurs.

Agave, Yucca, Aloe, Dracaena, Nolina and Cordyline can become massive trees, albeit not of the height of the tallest dicots, and with less branching.

Other genera in the order, such as Lomandra and Aphyllanthes, have the same type of secondary growth but confined to their underground stems.