Manual of Riyadh Plants

Part 1: Introduction

Plant Characteristics:

Basic guidelines and information have been set out in this

manual in order to clearly explain plant characteristics and the

extent of their adaptation to local environmental conditions as

follows:

Frost Tolerant Plants:

Defined as « the ability to withstand

frost in winter» where plants have been classified as follows:

• Low ability of frost tolerance: 0° C - 2° C.

• Medium ability of frost tolerance: -2° C - 5° C.

• High ability of frost tolerance: less than -5° C.

Drought and salinity:

Indicates the degree of plant resistance

to the extent of extreme climatic conditions such as high

temperatures in summer and the possibility of completely

dry leafs. The degree of salinity tolerance refers to the plants

tolerance to irrigation water characteristics.

Salinity is measured by parts per million of total dissolved

solids (TDS) as follows:

• Low saline: less than 1000 ppm.

• Medium saline: less than 2000 ppm.

• High saline: less than 3000 ppm.

• Intense saline: more than 3000 ppm.

Native plants use:

Almighty God has granted the native plants the unique manner

to adapt to the extreme climatic conditions of the region. Plants

avoid heat during peak daily temperatures and leaves bloom when

the temperatures are cool in the evenings. They also have functions

related to the storage of water in their root systems to resist drought.

The use of drought tolerant species, especially native/indigenous

plants is a more feasible and viable alternative to importing

exotic species which can be very expensive in terms of both

irrigation and maintenance.