obovate beakgrain
Diarrhena obovata (Gleason) Brandenberg

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Two species of beakgrain are native to the rich woodlands of eastern North America.  Only one species, obovate beakgrain, is found in Iowa, where it occurs widely (but often relatively sparsely) in woodlands in the southern two-thirds of the state.  This is one of the strangest of our grasses.  Relatively few grasses are restricted to forest habitats, but in addition, the relatively long leaves with a distinctly off-center midnerve and the unusual grains set this species apart.  The peculiar, leathery bottle-shaped grains distort the original shape of the spikelets greatly as they mature.  This grass flowers from June to October.  Despite the relatively late flowering period, obovate beakgrain is a cool season grass and does well in cultivation in moist, shady spots, indicating its ornamental potential.  It is easy to propagate from seeds so plants should not be dug, although they will grow from rhizomes.

Etymology: Diarrhena from the Greek dias = twice and arren = male, alluding to the 2 stamens; obovata from the Latin obovata = egg-shaped, referring to the egg- or bottle-shaped grains.


Plants perennial, with scaly rhizomes. Culms 37-120 cm tall, erect. Leaves with the sheaths overlapping and smooth to short-hairy; auricles sometimes present; blades (18-) 29-55 cm long, 8-15 mm wide, flat, smooth or slightly roughened or short-hairy. Flowering heads terminal, 5-26 cm long, 0.5-1.5 cm wide, borne above the leaves, narrow, branches ascending to erect. Spikelets 7-13 mm long, 3-11 mm wide, linear when young to ovate when mature; glumes unequal, lower glumes 2-3.2 mm long, 1/3-1/2 as long as the upper glume, upper glumes 2.6-4.2 mm long; lemmas 5.5-6.7 mm long, leathery at the center, thinner toward the margins, with 3 prominent nerves; paleas about ¾ as long as the lemmas, 2-keeled. Grains narrowing abruptly to the bottlenose-shaped beak, usually smooth and shiny and straw-colored at maturity. Chromosome number 2n = 60.


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