Leaf inclination in the coastal sand dune herb Hydrocotyle bonariensis Comm. ex Lam.

The Role of Phenotypic Plasticity among Largeleaf Pennywort (Hydrocotyle bonariensis) Populations Occupying Different Habitats in Coastal Georgia

“…1). Due to the patchy distribution of vegetation in coastal sand-dune habitats, there can be little to no canopy cover, and individual plants are often located within bare patches of sand where they experience direct sunlight for much of the day (Joesting et al 2016). Conversely, plants found in inland coastal plain habitats often grow in communities with a canopy of shrubs and/or small trees, which can provide shade, and subsequently can result in greater variation in light intensity within the habitat (Chiarello and Joesting 2018).…”

“…Taken together, the microenvironment of TI likely imposed a relatively greater risk of reduced photosynthesis and photoinhibition to Largeleaf Pennywort plants. Specifically, the relatively high level of incident sunlight may lead to excess light absorption and subsequent reduced photosynthesis through photoinhibition (Joesting et al 2016). Furthermore, the increased evaporative demand due to the high level of sunlight combined with the low water-holding capacity of the soil may result in greater water stress in TI populations, further exacerbating photoinhibition risk.…”

“…The difference in soil moisture and nutrient availability between the 2 habitats may lead to different patterns of biomass allocation, root morphology, and/or petiole and leaf cell size (Sultan and Bazzaz 1993a, b). Additionally, plants in coastal sand-dune habitats are often exposed to high levels of incident sunlight with little to no canopy cover, whereas plants in inland coastal plain habitats are often exposed to variable incident sunlight with at least some canopy cover (Chiarello and Joesting 2018; Joesting et al 2012, 2016). Too little incident sunlight can lead to reduced photosynthesis, while too much incident sunlight may result in photoinhibition and damage to the photosynthetic apparatus (Joesting et al 2012).…”

Leaf optical properties and dynamics of photosynthetic activity

“…For example, certain plants alter the leaf orientation angle with respect to the direction of irradiance and thus, during episodes of excessive radiation (e.g. midday on sunny days), their leaves gain a more vertical orientation to reduce the leaf area exposed to irradiance (Muraoka et al 1998;Joesting et al 2016). For similar purposes, certain plants fold their leaf margins during episodes of excessive irradiance (Huang et al 2012).…”