The question
Why do young sunflowers follow the sun while mature flower heads generally face east? A 2016 study by Atamian and colleagues investigated the relationship between growth, daily rhythms, and orientation.
What the study found
The researchers linked tracking to alternating stem elongation on opposite sides of the plant. Environmental responses and the internal circadian oscillator work together to coordinate the movement. Mature heads cease tracking.
What to observe
Record the developmental stage and orientation of the same plant at several times of day. Repeat observations over several days. Weather, location, and stage are context to record, rather than reasons to assume every plant behaves identically.
Read the sources.
An editorial research digest by Bloom. No affiliation with the cited institutions is implied.
