Related Concept Videos
02:00Photoreceptors and Plant Responses to Light
Light plays a significant role in regulating the growth and development of plants. In addition to providing energy for photosynthesis, light provides other important cues to regulate a range of developmental and physiological responses in plants.
02:16Light Acquisition
In order to produce glucose, plants need to capture sufficient light energy. Many modern plants have evolved leaves specialized for light acquisition. Leaves can be only millimeters in width or tens of meters wide, depending on the environment. Due to competition for sunlight, evolution has driven the evolution of increasingly larger leaves and taller plants, to avoid shading by their neighbors with contaminant elaboration of root architecture and mechanisms to transport water and nutrients.
02:45Biological Clocks and Seasonal Responses
The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
01:24Color Vision
Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.
01:19Pigmentation
The color of the skin is influenced by a number of pigments, including melanin, carotene, and hemoglobin. Recall that melanin is produced by cells called melanocytes, which are found scattered throughout the stratum basale of the epidermis. The melanin is transferred to the keratinocytes via melanosomes.
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
01:57Adaptations that Reduce Water Loss
Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.
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Updated: Jun 3, 2026
11:09
Relating Stomatal Conductance to Leaf Functional Traits
Published on: October 12, 2015
Winter leaf reddening in 'evergreen' species.
1Department of Biology, Wake Forest University, Winston-Salem, NC 271069-7325, USA. nhughes@highpoint.edu
The New Phytologist
|March 8, 2011
Summary
Winter leaf reddening in evergreens is poorly understood. This review explores its biochemistry, physiology, and ecology, focusing on photoprotection as a potential adaptive function.
Area of Science:
- Plant Biology
- Ecology
- Biochemistry
Background:
- Autumn leaf reddening in deciduous trees is well-studied.
- Winter leaf reddening in evergreen species across various climates is largely overlooked.
- The functional significance and species-specific occurrence of winter reddening are unclear.
Purpose of the Study:
- To review the biochemistry, physiology, and ecology of winter leaf reddening.
- To explore the potential adaptive functions of winter leaf reddening.
- To highlight outstanding questions and future research directions.
Main Methods:
- Literature review of scientific studies on winter leaf reddening.
- Analysis of existing data on the biochemistry and physiology of red versus green winter leaves.
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10:20Evaluation of Photosynthetic Behaviors by Simultaneous Measurements of Leaf Reflectance and Chlorophyll Fluorescence Analyses
Published on: August 9, 2019
10:14Reconstructing Terrestrial Paleoclimate and Paleoecology with Fossil Leaves Using Digital Leaf Physiognomy and Leaf Mass Per Area
Published on: October 25, 2024
Main Results:
- Winter reddening is linked to increased sunlight and potentially lower nitrogen content.
- Red leaves may exhibit shade acclimation, supporting a photoprotective role.
- Despite similar photosynthetic capacities, winter-red and winter-green species coexist in high-light environments.
Conclusions:
- Photoprotection is a leading hypothesis for winter leaf reddening, but not fully supported by all observations.
- Factors driving interspecific differences in winter leaf color remain elusive.
- Further research is needed to elucidate the adaptive significance and ecological drivers of winter reddening.