Lantana Umbels

A perennial flowering plant in the verbena family, Verbenaceae.
Lantana, both here in China and in Australia is a noxious choking weed which spreads a dense thorny woody canopy over the ground excluding all other native vegetation and preventing germination of new growth. It is near impossible to eradicate and nothing will eat it, arthropod or mammalian. Innocuous ornamental garden varieties have been developed that are not as precocious. There are perhaps two upsides: the thicket Lantana produces is a great protective habitat for small birds; and the flowers are brilliantly colored and intricately designed and attract masses of insect pollinators.
I am curious what, if anything, determines the patterns these blooms create when opening, both the order in which the individual blooms in the umbel open, and their color sequence. The predominant shape is obviously pentagonal and sometimes extremely precise........