One of the commonest grasses found in hedges and thickets in this country, more especially on the lighter soils, is the Tall Oat Grass (Arrhenatherum avenaceum, Beauvais). In meadows it is generally present, abundantly on some soils, while occasionally it forms part of the “seeds” mixture put down for temporary or permanent pasture. In some localities a form of this grass known as “Onion Couch” becomes a dangerous weed on the arable land—this plant is identical in outward appearance with the Tall Oat Grass except at the base of the stems where the nodes swell and form chains of bulbs each of which is capable of breaking off and giving rise to a new plant. This habit of growth together with a liberal supply of seeds formed in June and July make it a very difficult weed to eradicate. Its occurrence is usually reported from the lighter soils, but in the West of England the heavy land is equally badly affected.