Sub-species
subsp. vulgare
This sub-species is the cultivated form and appears in a diverse range of habitats that concentrating in temperate regions and at high altitudes in the tropics and subtropical regions. It is the fourth most important cereal crop in the world after a wheat, maize and rice and approximately 136 million tonnes of barley is produced annually, primarily with 86% for animal feed and for malt production. Human consumption of barley is in the form of flat bread or porridge or used in baby foods, health foods and thickeners. It is also used in the brewing industry for the production beer and alcohol.

subsp. spontaneum
This sub-species is the wild form and is naturally found in the Middle East and adjacent regions of North Africa.  Commonly grows in bended fields or along roadsides in disturbed soils that and was first domesticated about 10,000 years ago.

Note: 
There are 2-forms of barley both have spikelets in triplets that are arranged alternately along the rachis. The two-row barley only has a fertile central spikelet and is commonly grown for malt and the 6-row barley where all the spikelets are fertile that has a higher protein content and is used in food.

Cultivar
There are many named varieties available.
'Variegata'
This annual grows to 1 m (3 ft) tall and has mid green leaves with whitish margins. It is planted parks and gardens along borders for foliage contrast or used around water features for reed-like effect.