page_title: Drought tolerance
section_title: Natural drought tolerance adaptations
hierarchical_section_title: Drought tolerance / Natural drought tolerance adaptations
caption_attribution_description: Scarlet globemallow is one of the most common wildflowers (forbs) in the sage-steppe habitat on and adjacent to Seedskadee NWR. In addition to being a hardy perennial forb, scarlet globemallow is memorialized in history as the last plant collected by Meriwether Lewis on the Lewis and Clark Expedition. Native Americans chewed scarlet globemallow and applied it as a paste to relieve the pain of burns and flesh wounds. This perennial forb, with a stout taproot, grows 3 to 18 inches in height, topped with deep orange or light pink to brick red flowers. Leaves are grayish-green and palmately lobed. Both the leaves and the several erect stems are covered with silver-gray hairs that reflect solar radiation and protect against drying. These hairs, along with its deep root system, make it very drought tolerant. Scarlet globemallow exhibits low seed germination due to a hard seed coat and reproduces mainly by rhizomes. The hard seed coat enables long-term seed viability in the seedbank. Seeds then germinate when conditions are occasionally favorable. Scarlet globemallow is eaten by almost all species of herbivores where it occurs and can be an important component of wildlife diets. It stabilizes the soil on disturbed areas through creeping rhizomes and proliferates until grasses out-compete it. Deep roots allow it to survive disking, fires, and grazing. When other species are eliminated, scarlet globemallow proliferates.Although scarlet globemallow is suppressed when grasses and shrubs begin growing, it will proliferate again once a disturbance occurs. This, along with its drought tolerance and soil stabilizing ability, make it a promising restoration species. Seeds are hard to collect, making them expensive, and the germination rate is very low. Photo: Tom Koerner/USFWS
context_page_description: Drought tolerance is the ability to which a plant maintains its biomass production during arid or drought conditions. Some plants are naturally adapted to dry conditions, surviving with protection mechanisms such as desiccation tolerance, detoxification, or repair of xylem embolism. Other plants, specifically crops like corn, wheat, and rice, have become increasingly tolerant to drought with new varieties created via genetic engineering.
  The mechanisms behind drought tolerance are complex and involve many pathways which allows plants to respond to specific sets of conditions at any given time. Some of these interactions include stomatal conductance, carotenoid degradation and anthocyanin accumulation, the intervention of osmoprotectants, ROS-scavenging enzymes. The molecular control of drought tolerance is also very complex and is influenced other factors such as environment and the developmental stage of the plant. This control consists mainly of transcriptional factors, such as dehydration-responsive element-binding protein, abscisic acid-responsive element-binding factor, and NAM.
context_section_description: Plants in naturally arid conditions retain large amounts of biomass due to drought tolerance and can be classified into 4 categories of adaptation:
  Drought-escaping plants: annuals that germinate and grow only during times of sufficient times of moisture to complete their life cycle.
  Drought-evading plants: non-succulent perennials which restrict their growth only to periods of moisture availability.
  Drought-enduring plants: also known as xerophytes, these evergreen shrubs have extensive root systems along with morphological and physiological adaptations which enable them to maintain growth even in times of extreme drought conditions.
  Drought-resisting plants: also known as succulent perennials, they have water stored in their leaves and stems for sparing uses.
caption: The scarlet globe mallow (Sphaeralcea coccinea) is a drought-escaping plant with natural drought tolerance. Some of its natural adaptations include silver-gray hairs that protect against drying; a deep root system; and having seeds that only germinate when conditions are favorable.
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