The underlying color of foliage is yellow–leaves begin yellow and turn green when they begin to produce chlorophyll. So why do some trees go to the trouble of turning fiery red in fall?
There are several theories. Some woody plants, vines in particular, turn red to signal to birds that their berries are ripe (birds have excellent color vision). Virginia creeper and poison ivy, two native vines that are particularly beneficial to wildlife, turn fiery red in fall, usually while the trees around them are still green. Ecologists call this a foliar flag.
But maples and tupelos both flaunt bright red foliage in fall, although their fruits ripen much earlier in the season. Why do the trees waste all the energy it takes to produce red pigment? There are many theories: to protect against insect damage or sunburn at the crucial time of leaf abscission, or to fool insects into thinking the tree is dying; they’re neatly summarized in today’s NY Times. Read about it there, and be sure to get outside and enjoy the short-lived show. There are lots of lovely red and sugar maples around our area, and even a few tupelos.
I’ll leave you with a brain teaser: the foliage of which native shrub turns a deep purple/pink color in fall?