How to Identify Drought Tolerant Plants

 

Yantis Lakeside Gardens

Living and Gardening in the

Beautiful Texas Hill Country



                                
           How To Identify Drought Tolerant Plants
By Robert & Sheryl Yantis

All plants need sunshine, air, water and soil to survive.  Native plants and some adapted plants have become efficient at accessing, storing and using water.  Most plants get their water from the ground. Drought tolerant plants have developed good root systems which enable them to survive droughts.  A deep taproot or thick fleshy roots can allow them to store water and energy even when they lose their leaves.  
In addition to good root systems, plants adapt to low rainfall by becoming more efficient in their use of water. Some plants hide water in water swollen bulbs or rhizomes in the ground while others have adapted their leaves to efficiently store water and to prevent evaporation. Leaves can be a major source of water loss for plants. The best way to identify drought tolerant plants is to look for drought tolerant adaptations they have made.

Small leaves shed heat and reduce evaporation and thereby reduce the plants water loss. This includes thyme and yaupon holly.

Long narrow leaves are very good at shedding heat without losing water. This group includes many native grasses.

Leaf needles are tough, thin, waxy leaves that try to prevent water loss.  Many of these plants also contain volatile oils such as rosemary and lavender.

Succulent or fleshy leaves store moisture for hot or dry period. Fleshy leaves and thick waxy skin on sedum, ice plant and yucca, to name a few, help them conserve water. Other plants, such as some euphorbias, have fleshy stems that serve the same purpose.

Grey and Silver leaves reflect heat and light and usually indicate drought resistance.  Plants such as artemisia and russian sage are included in this group.

Hairy or woolly leaves shade themselves with their own leaves.  Hairs on the underside of the leaves raise the humidity of the surrounding air and slow down air movement which slows evaporation. Lambs ear is good example.

Leathery foliage loses less water than soft leaves.

Waxy leaves have a shiny surface which reduces evaporation especially in windy weather. Pine trees and pittosporum are good examples.

Aromatic leaves contain scented volatile compounds that appear to increase the air density around them and cool foliage as they evaporate. Have you noticed that many plants that have adapted to drought conditions have aromatic leaves?  These plants include a variety of salvias/sages, germander, catmint, yarrow, rosemary, lavender to name only a few.

Slow growth -  By restricting the growth of leaves and stems, plants can conserve limited supplies of water. Many cacti and succulents have utilized this strategy.

Underground storage devises enable plants to save water for long periods.  Most bulbs flower when water is plentiful and are dormant during the hottest and driest months. Some lilies such as school house lilies bloom after the first rain in fall, others like rain lilies after a rain and plants such as daffodils bloom in the spring.

The hill country has an abundance of beautiful native and some adapted plants which have naturally adapted to this area and most of these plants also have lower water demands. There are many drought tolerant plants that allow us to have beautiful gardens even in a drought.