Letters from the Feb. 7, 2004, issue of Science News.

Warm topic

I was fascinated by the article on heat production in flowers (“Warm-Blooded Plants?” SN: 12/13/03, p. 379: Warm-Blooded Plants?). It speculated on the evolutionary origins of such thermogenesis and observed how it predominates in ancient lineages of flowering plants like magnolias and water lilies. But thermogenesis goes back much farther than this, for it also occurs in cycads, nonflowering plants that arose in the Paleozoic.