Jo Ann, you'll have more luck finding Matrona if you spell it correctly. You've spelled it "Metrona" in three posts in this thread.
Greene, many (but not all) of the plants once known as sedums have been reclassified as plants of other genera. When this happens, the name is corrected, but the previous name is entered as a synonym. When you browse all of the plants in the Sedum genus, therefore, you'll find entries for plants of the Hylotelephium, Phedimus, and other genera if the Sedum genus is also listed as a synonym.
The list is in alphabetical order by species.
http://garden.org/plants/brows...