In the study, the researchers looked at the Tasmanian blue gum tree, and found it appears to use its internal clock to regulate its intake of water and carbon dioxide.
Both carbon-dioxide intake and water loss declined in the six hours after dusk, but increased noticeably during the six hours before dawn, even on nights when temperature and humidity remained constant. Because the environment wasn't changing, the increase can only be explained by the biological clock, said study researcher Víctor Resco de Dios of the University of Western Sydney in Australia." LiveScience
And God said, Let the earth bring forth grass, the herb yielding seed, and the fruit tree yielding fruit after his kind, whose seed is in itself, upon the earth: and it was so.
Genesis 1:11