I have so many beds of mums that do so well here in zone 7 New Mexico. Most of the plants several years old & some now like large 'bushes'! I noticed that in a bed of mixed colors that the leaves are different sizes,shapes on some of the different colors; some bushes stay rather small but others grow like a bushel basket ! ... & they bloom at different times in the Fall. They are all ?'chrysanthemums' but why do the plants differ in size & leaf shapes? Are they long lived like mine seem to be ... & how long can one plant be expected to live? When I prune them in mid summer, I hated to toss the clippings so I put the clippings in root stimulator & plant them! Amazing how so many of the clippings do take root for more plants! Sadly we buy the mums in flower in Fall to plant so we can see the different blooms/colors- but it then doesn't give much time for them to adjust for winter !