Rivet wheat

Triticum turgidum (rivet wheat, also known collectively with its subspecies as durum or macaroni wheat) is an annual grass of the family Poaceae, growing 1–1.5 m tall on stout, jointed, hollow culms. The flat, linear, parallel-veined leaf blades arise from sheathing bases and bear a small membranous ligule at the junction with the sheath. The inflorescence is a dense terminal spike (ear) bearing two ranks of sessile spikelets pressed close to a tough rachis, each spikelet containing 3–5 florets enclosed by two firm keeled glumes; the lemmas are typically long-awned, giving the ripe ears a bristly, bearded appearance. The grain is a large, hard, vitreous caryopsis higher in protein and gluten than common bread wheat. An allotetraploid (genome AABB), T. turgidum is native to the eastern Mediterranean Basin and adjacent western Asia from Iran east into Xinjiang, but as one of the oldest domesticated wheats it has been cultivated throughout temperate regions worldwide for several millennia; subsp. durum accounts for about 8% of the world's wheat acreage and is the principal raw material for pasta and semolina.