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Perennial Ryegrass (Lolium perenne L.)


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Perennial Ryegrass (Lolium perenne L.)


Perennial ryegrass (Lolium perenne L.), is a cool-season perennial bunchgrass native to Europe, temperate Asia, and North Africa. It is widely distributed throughout the world, including North and South America, Europe, New Zealand, and Australia.

Perennial ryegrass is important in forage/livestock systems. High palatability and digestibility make this species highly valued for dairy and sheep forage systems. As a result, it often is the preferred forage grass in temperate regions of the world.

Characteristics include:

  • High yield potential
  • Fast establishment
  • Suitability for reduced-tillage renovation
  • Use on heavy and waterlogged soils

In the United States, perennial ryegrass is used for forage predominately in the coastal Northwest, irrigated intermountain valleys of the West, the Midwest, and Northeast.

Perennial ryegrass can behave as an annual, short-lived perennial, or perennial, depending on environmental conditions. It resembles annual ryegrass (Lolium multiflorum Lam.), although perennial ryegrass has more leaves in lower parts of the plant canopy, its collar and blade are more narrow, and lemmas are awnless.




Perennial ryegrass, like other grasses, may be identified by floral parts (inflorescence, spikelet, and seed) or vegetative parts (leaf, stem, collar, and root).

Inflorescence (seed head)

The inflorescence is a spike 2 to 12 inches (5 to 30 cm) long. It has 5 to 40 alternately arranged spikelets attached edgewise directly to the central axis (rachis). Lemmas are awnless, in contrast to annual ryegrass. See Figures.

  • Inflorescence—Flowerhead terminating the stem
  • Peduncle—Uppermost culm (flowering stem) segment
  • Spikelet—Unit of the grass flowerhead


Spikelets contain 3 to 10 florets. The terminal (end) spikelet has two glumes, but the inner glume is absent in the other spikelets. See Figures.

  • Floret—Lemma and palea with the enclosed flower
  • Glume—Two usually empty bracts at the base of the spikelet


Lemmas of perennial ryegrass are awnless. In contrast, annual ryegrass is awned. See Figures.

Seeds per pound average 237,000 (521,000 per kg), with a range of 200,000 to 265,000 per pound (440,000 to 583,000 per kg). Perennial ryegrass seeds are 0.2 to 0.3 inches long (5 to 8 mm), and width at the midpoint is 0.04 to 0.06 inches (1 to 1.5 mm).

  • Lemma—The lower of two bracts enclosing the flower
  • Palea—The upper of two bracts enclosing the flower
  • Rachilla—Main axis of the spikelet
  • Seed—A ripened ovule containing an embryo with a seed coat, often with additional storage tissues


Flowering stems (culms) are comprised of nodes and internodes, each node bearing a leaf. Culms are 12 to 40 inches in height (30 to 100 cm) depending on variety, moisture, and site conditions. The uppermost culm segment is called the peduncle, the structure that supports the flowering parts. The stem base commonly is reddish.

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