Phalaris(redirected from Phal'aris)
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Related to Phal'aris: Phalaris aquatica
a grass genus of the Poaceae family containing some of the best pasture grasses which can, on occasion, be poisonous. Cause two kinds of poisoning: (1) acute heart failure and sudden death in sheep—caused by P. aquatica, P. arundinacea and Rhompa grass (a hybrid variety); (2) incoordination with tremor and head nodding, finally recumbency and convulsions. (Called also phalaris staggers and caused by all species.) New cases occur for many weeks after removal from the pasture. There is a characteristic gray-green discoloration of the brainstem and midbrain. Includes P. aquatica (P. tuberosa, Toowoomba canary grass), P. arundinacea (reed canary grass), P. minor (canary grass), P. angusta, P. brachystachys, P. canariensis, P. caroliniana and Rhompa grass, a hybrid form. Toxins include β-carbolines, tryptamine and indole alkaloids.