Back in 1998, (when he should have been working on his Ph.D. dissertation on Surf Clams at the
Institute of Marine and Coastal Sciences of Rutgers University), Eric J. Weissberger published this entertaining but superficial treatment of the evolution of chia pets in the Annals of Improbable Research (AIR).
AIR is the organization that each year awards The Ig Nobel Prize to honor achievements that "first make people laugh, and then make them think".
The prizes are intended to celebrate the unusual, honor the imaginative
-- and spur people's interest in science, medicine, and technology. Last year the Ig Nobel Prize in chemistry went to Mayu Yamamoto of the International Medical Center of Japan,
for developing a way to extract vanillin -- vanilla fragrance and flavoring
-- from cow dung.
Anyway, Dr. Weissberger investigated the family Chiaceae (chia pets), which he claims is the first known missing link between plants and animals. He discusses the nature of the cardboard cocoon and the role played by the human host in facilitating the synchronous hatching of chia pets on December 25th each year.

Dr. Weissberger speculations that chia pets are descended from a common ancestor (i.e., they are monophyletic), but acknowledges that convergent evolution cannot be ruled out from the (non-existent) fossil record.
He goes on to suggest that chia pets may, in fact, be closely related to humans, as evidenced by the existence of the Chia Professor!
Unfortunately, Dr. Weissberger now works at the Environmental Protection Agency (EPA) and has turned his back on his earlier work with chia pets. He has become known as an expert on surf clams!