28 GRASSES OF SCOTLAND. 



soils. It grows naturally by the sides of rivers and standing pools. 

 Its limit of altitude is about 1000 feet above the sea. 



It is frequent in Scotland, England, and Ireland, but has not been 

 found in Lapland, Norway, or Sweden, and does not seem to exist 

 further north than latitude 59. It is common in Germany and the 

 southern parts of Europe, but quite unknown in America. 



Flowers in the second week of July, and ripens its seed about the 

 middle of August. 



16. HORDEUM MURINUM.* 



Wall-Barley. 



Specific Characters. — Glumes of central spikelet dilated and fring- 

 ed. (Plate X.) 



Description. — It grows from twelve to eighteen inches high. The 

 root is annual, fibrous. Stem round, smooth, erect ; bearing three or 

 four leaves, with smooth striated inflated sheaths, the upper sheath 

 longer than its leaf, crowned with a short ragged ligule. Joints 

 smooth. Leaves linear, acute, flat, roughish, slightly hairy on both 

 surfaces, the edges minutely serrated. Inflorescence spiked. Spike 

 usually about two inches in length, linear, very dense, and uni- 

 form ; rachis jointed, very brittle, toothed ; the intermediate spaces 

 flattened and bordered. Spikelets arranged in threes at each tooth of 

 the rachis, (Fig. 4) ; of one-awned floret. Calyx of the central spike- 

 let of two glumes of equal lengths, dilated, fringed, terminating in a 

 long straight rough awn, (Fig. 1.) Central fioret of two palese ; the 

 outer palea ovate, three-ribbed, terminating in a long rough awn 

 longer than the glumes ; the inner palea membranous, pellucid, mi- 

 nutely fringed at the margins, and furnished with a small bristle at 

 the base. Lateral spikelets pedunculated ; the calyx of two glumes, 

 (Figs. 2 and 3,) bristle-shaped, the innermost slightly dilated, and often 

 somewhat fringed at the base. Lateral jlorets imperfect, with stamens 

 only ; of two paleee, the outer palea three-ribbed, terminating in a 

 long awn longer than the glumes ; inner palea membranous, with a 

 delicate bristle at the base. 



Q])s, — Hordeum murinum is distinguished from Hordeum mariti- 



* Hordeum murinum, Koch, Smith, Hooker, Greville, Lindlcy. 



