BIOL 120A Chapter 12: Detailed Notes Chapter 12
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The stems or culms are often hollow between the nodes and usually unbranched. The two stems are aboveground stolon or underground rhizomes. Surrounding each flower are two bracts, the outer lemma and inner palea the flower and the two bracts together make up a floret. One to 12 florets are arranged on a spikelet which also may be subtended by two bracts called glumes. Awn is a slender bristle can be seen extending from either a glume or a lemma. Grains which are dry and single-seeded indehiscent fruits. The bracts that surrounded the flower now surround the grain and are called chaff. The outer wall of the grain, consisting of the fruit wall fused to the seed coat, is known as the bran. Interior to the bran is a layer of enlarged cells known as the aleurone layer that is normally high in protein. An important component of flour for the elasticity it provides.
