Hordeum murinum, commonly known as wall barley or false barley, is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of grass

Poaceae

The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...

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They can grow to 30 cm in height and its unbranched spikes can reach 10 cm long. It is quite widespread and common. It grows during May - July in mainly costal areas. It produces small, dry nutlets and its leaves can be 8 cm wide with short blunt Ligules.

It is absent throughout most of Ireland and Scotland but is common in England and Wales.