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Grasses of the Eloise Butler Wildflower Garden

The oldest public wildflower garden in the United States

Blue Oatgrass

Common Name
Blue Oatgrass

 

Scientific Name
Helictotrichon sempervirens (Vill.) Pilg.

 

Plant Family
Poaceae (Grasses)

Garden Location
Upland

 

Prime Season
Evergreen, flowers in June

 

Grass structure and definitions - PDF from Oregon State University

Ligule Types, Shapes & Margins (pdf)

 

Blue Oatgrass is a perennial clump forming ornamental grass that forms a mound of spiky, silvery blue foliage that resemble a miniature water fountain. Stems (culms) grown 12 to 40 inches in height and are erect.

Leaves: The clump has coarse wiry leaves that will reach to about 24 inches in length on a good specimen. They are very narrow, only 2 to 4 mm wide but usually with edges rolled over. They can be smooth or with a rough surface. Leaves are evergreen, with older basal dead leaves turning brown and either dropping or being hand removed.

Sheaths & Ligules: Leaf sheaths are open to their base, auricles absent, ligules are truncate to rounded, 0.5 to 1.5 mm, almost as long as wide.

Inflorescence: Rising above the foliage in early June on flowering stems that can reach two feet above the foliage are the wispy oats-like seed panicles that turn a straw-color when mature. Panicles are 3 to 8 inches long, narrow, branched, with each branch having 3 to 7 spikelets. Side branches of the panicle have fine hair.

Spikelets: Spikelets are compressed, 10 to 14 mm long, usually with 3 florets but there can be 5. The glumes are not equal in size, the lower 7 to 10 mm and the upper 10 to 12 mm in length, almost as long as the spikelet. They are 1 to 3 veined. The lowest lemmas are 7 to 12 mm long, 3 to 5 veined with pointed, toothed tips and an awn about 15 mm long which is twisted with a sharp bend. Florets have 3 anthers.

 

Habitat: It is a cool season grass, preferring drier well drained sites. It will flower in Minnesota in early June as these photos from the Garden indicate, once the plant is established, and if it gets full sun, and is not over-watered. The grass remains semi-evergreen during the winter in a cool climate like Minnesota. Because of it's evergreen characteristic, Blue Oatgrass is not trimmed back in the spring, or otherwise new growth is severely affected. Old dead leaves are simply combed out by hand.

Names: The species of Helictotrichon (he-lik-toh-TRI-kon) are considered a "neutral grass" - that is they look like grasses but having evergreen characteristics, don't act like grasses. The name comes from the Greek helictos, meaning 'twisted' and trichon, meaning 'awn' - together referring to the twist in the lemma awn. The species name, sempervirens, is derived from two Latin words - semper, meaning 'always' and vivus, meaning 'alive' or 'living' and together referring to the 'evergreen' characteristic of the plant. The author names for the plant classification are as follows: First to publish was ‘Vill.’ which refers to Dominique Villars (1745-1814) French botanist who described over 2700 plants in Historie des plantes de Dauphine. His work was was updated and amended by ‘Pilg.’ which refers to Robert Knud Friedrich Pilger (1876-1953), German botanist, specialist in conifers, and director of the botanical garden at Berlin-Dahlem.

Comparisons: The only other species of Helictotrichon found in the wild in North America is H. mortonianum, Alpine Oatgrass, and it is restricted to 4 states of the Rocky Mountain Region. It is considered native. It is much smaller, reaching only to 8 inches high, with panicles no longer than 8 cm and the panicle branches usually have only 1 spikelet.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

Blue Oat Grass plant Blue Oat Grass seed

Above: A clump of Blue Oatgrass in the summer during flowering. The oats-like flowering stem of Blue Oatgrass terminates in an erect branched panicle.

Below: Clumps of Blue Oat Grass in the Upland Garden in flower in early June 2009.

Blue Oat Grass

Below: Comparative drawing of the both species of Helictotrichon . Note the much larger size of the spikelet of H. sempervirens. Drawing Illustrators - Linda A. Vorobik and Hana Pazdírková, ©Utah State University.

drawing

Notes:

Blue Oatgrass is a non-native grass that is native to the southwestern Alps region of Europe. It was imported into the United States as an ornamental grass and a number of cultivars have been developed in the nursery trade. It is not known to be growing naturally in the wild.

References and site links

References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.

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