Aerial Root Physiology: Reaching for the Sky or Down to Earth?

Abstract

Aerial roots have evolved in plants from diverse ecosystems, many facing specific environmental challenges associated with their natural or agricultural setting. In coastal species exposed to wind and waves, including mangroves, soft anoxic substrates have resulted in highly developed aerial root systems. In the rainforest, aerial roots of hemi‐epiphytic figs enable life to begin higher in the canopy while climbing plants, such as ivy and Monstera s, depend on structurally very different aerial roots to climb vertical substrates. Maize, globally one of the three most important cereals, develops aerial roots presumably reducing lodging in high winds. In each of these cases, the dominant hypothesized role for aerial roots is to provide support and enabling greater heights to be reached. But do aerial roots of these plant groups also contribute to resource uptake and movement? This article explores the current knowledge of aerial root physiology and structure from each of these interesting and challenging environmental conditions and discusses how understanding these adaptations and niche requirements has value for improving crops, protecting our coastlines, improving our urban green spaces, and managing biodiversity conservation.

Maize plants and the brace roots that support them

“…The positive relationship between the production of stem‐borne roots and plant growth may be conserved in other large monocot plants. Specifically, Pandanus is a monocot species that shows a strong correlation between plant height and the number of aerial stilt roots, although in this case it was hypothesized that the relationship is due to the increasing demand for structural support in taller plants rather than physiology (Rasmussen et al ., 2018). Overall, there is unexplored potential for understanding brace root functions other than structural stability.…”

Aerial roots elevate indoor plant health: Physiological and morphological responses of three high‐humidity adapted Araceae species to indoor humidity levels

“…These canopy soils can contain a higher density of fine roots than the humus layer on a forest floor (Gotsch et al, 2016) and roots of trees have been shown to forage agravitropically to escape the below‐ground competition in terrestrial soil environments (Sanford, 1987). With less competition in canopy soils it is perhaps unsurprising so many species have evolved aerial roots to exploit these aerial nutrient sources (reviewed in Rasmussen et al, 2019). However, while there is now some important evidence that aerial roots in the Araceae family are required for water supply (Liz Filartiga et al, 2021; López‐Portillo et al, 2000) nothing is known about their nutrient uptake ability.…”

“…This makes them easy to share or multiply in our own homes (Croat & Ortiz, 2020) but also makes them ideal for large indoor gardens where hundreds or thousands of plants might be required. In their native forest environment these adventitious roots are extremely important adaptations for their nomadic, hemi‐epiphytic or truly epiphytic growth habits (Rasmussen et al, 2019; Tenorio et al, 2014). Adventitious roots have evolved many times and with different morphologies and functions from aerial clinging roots for climbing and support, to feeder roots that head groundward in search of water and nutrients (Croat & Ortiz, 2020; Liz Filartiga et al, 2021; Rasmussen et al, 2019; Tenorio et al, 2014).…”

Dynamics Simulation of Radial Flow Water in Aerial Roots of Corn by Deposit of Dew in Atmosphere Aerial Roots Continuum

“…We are also confronted with the management of the environment and the substantial sustainability of the ecosystem made up of various plants with very varied root systems. Hence the need to understand how these different species through their roots can adapt to climatic conditions linked to their living environment [4]. Some authors made a comparative study of the different types of Adventist roots of certain types of plants in relation to their living environment.…”

“…Some authors made a comparative study of the different types of Adventist roots of certain types of plants in relation to their living environment. They found that these roots have several functions [4]. They develop on plants in response to stressful conditions, such as soil degradation, nutrient deficit, and play an important role in the development of areas such as economy, ecology and human existence [5].…”