Figure 8.

Graphic summary. When plants grow in dense communities, the R:FR light ratio decreases through R absorption and FR reflection, which is perceived in the petioles and causes a local increase in auxin and gibberellin (GA), but a reduction in brassinosteroid (BR) in shade‐avoiding plant species Geranium pyrenaicum (left). These changing hormone levels regulate the elongation of petioles, which facilitates shade escape. When shade‐tolerant species G. robertianum (right) is exposed to FR‐enriched light, this does not affect hormone synthesis or signaling, which results in no elongation response in its petioles