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Lolium temulentum Minimize

GENUS: Lolium

Lolium temulentum L - Darnel

FAMILY: Gramineae (Poaceae)—the Grass Family

This huge, economically important group contains several hundred genera and many thousand species. All of the world's food grains belong to this family, as do bamboo, lawn and turf species, sugar cane, and many other plants vital to humans. Very few species are poisonous. Foxtail grass (Setaria spp,) and squirreltail (Hordeum jubatum L ) have hard, sharp, floral parts that produce mechanical damage to the eyes, mouth, and digestive system of livestock; others host parasitic fungi that produce toxins (see Claviceps).

Flowers in the grass family are highly modified and require special terminology. The basic reproductive unit is a floret, consisting of a flower having either male or female (or commonly both) parts, the stamens and ovary, and scales, the lodicules. In addition to the flower, the floret contains lemmas (bracts) and palea (a bract). The collection of florets constitutes a spikelet that can easily be recognized by one, or more often two, bracts called the glumes. The grass leaf is modified into leaf sheath, ligule, and blade The sheath is the base of a grass leaf originating from a stem node. The blade is the flat, foliar, free portion of the leaf. The ligule is an outgrowth between the leaf sheath and blade. The vast diversity in size, shape, and arrangement of the reproductive and vegetative organs is used to distinguish grass species. Grass characteristics include, the flower: 3-merous; leaf veins: parallel; stamens: (1-) 3 (-6), separate, filaments slender; ovarv: superior, 1-celled, 1-seeded; styles: (1) 2 (3), usually featherlike; fruit: achene. an indehiscent seedlike structure sometimes permanently enclosed between the lemma and palea.

PHENOLOGY: Lojium temulentum flowers June through August.

DISTRIBUTION: This weed of grain fields and waste places is uncommon in Pennsylvania. Distribution records indicate sporadic occurrence in the southeastern corner of the state.

PLANT CHARACTERISTICS: Darnel is an annual grass with stems: solitary or a few clumped together, 4-8 dm tall; blades: glabrous beneath, scabrous above, 3-9 mm wide; spike: 1-2 dm; spikelets: placed edgewise to the rachis, 5-8 flowered; glume: firm, straight, 5-7 nerved, equalling or surpassing the uppermost lemma, 12-22 mm; lemmas: obtuse, awned, or awnless.

POISONOUS PARTS: The seeds and seed heads are considered poisonous.

SYMPTOMS: In humans, darnel poisoning is characterized by the sensation of intoxication, ataxia, giddiness, apathy, various abnormal sensations, mydriasis, nausea, vomiting, gastroenteritis, and diarrhea. It is rarely fatal.

POISONOUS PRINCIPLES: The alkaloids temuline and loliine possibly are responsible for toxicity of darnel. It also has been suggested that toxicity may be due to a parasitic fungus living within the seed head.

CONFUSED TAXA: The nontechnical characters in the illustration should readily distinguish darnel from the numerous other grass species found in Pennsylvania. The linear leaves have narrow horns (auricles) at the sheath-blade junction; the ligule is membranous and truncate; the spike is rigid, 5-40 cm long, and composed of 5-15 spikelets each 8-26 mm long.

SPECIES OF ANIMALS AFFECTED: Though cases of darnel poisoning are rare, humans and livestock are susceptible.

TREATMENT: ( l l a)(b); (26)

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