The perianth is reduced to two scales, called lodicules, : 11 that expand and contract to spread the lemma and palea these are generally interpreted to be modified sepals. The flowers are usually hermaphroditic- maize being an important exception-and mainly anemophilous or wind-pollinated, although insects occasionally play a role. : 13 A floret consists of the flower surrounded by two bracts, one external-the lemma-and one internal-the palea. A spikelet consists of two (or sometimes fewer) bracts at the base, called glumes, followed by one or more florets. The part of the spikelet that bears the florets is called the rachilla. : 12 The spikelets are further grouped into panicles or spikes. 1 – glume, 2 – lemma, 3 – awn, 4 – palea, 5 – lodicules, 6 – stamens, 7 – ovary, 8 – styles.įlowers of Poaceae are characteristically arranged in spikelets, each having one or more florets. However, all of them belong to the monocot group of plants. The rushes and sedges are related to the Poaceae, being members of the order Poales, but the seagrasses are members of order Alismatales. Though they are commonly called "grasses", groups such as the seagrasses, rushes and sedges fall outside this family. Grasses are also an important part of the vegetation in many other habitats, including wetlands, forests and tundra. Grasslands such as savannah and prairie where grasses are dominant are estimated to constitute 40.5% of the land area of the Earth, excluding Greenland and Antarctica. The leaf grows from the base of the blade, an adaptation allowing it to cope with frequent grazing. The lower part of each leaf encloses the stem, forming a leaf-sheath. Grasses have stems that are hollow except at the nodes and narrow alternate leaves borne in two ranks. Some members of the Poaceae are used as building materials ( bamboo, thatch, and straw) others can provide a source of biofuel, primarily via the conversion of maize to ethanol. They provide, through direct human consumption, just over one-half (51%) of all dietary energy rice provides 20%, wheat supplies 20%, maize (corn) 5.5%, and other grains 6%. The Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops such as maize, wheat, rice, barley, and millet as well as feed for meat-producing animals. With around 780 genera and around 12,000 species, the Poaceae is the fifth-largest plant family, following the Asteraceae, Orchidaceae, Fabaceae and Rubiaceae. The latter are commonly referred to collectively as grass. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns and pasture. Poaceae ( / p oʊ ˈ eɪ s i aɪ, - s iː iː/) or Gramineae ( / ɡ r ə ˈ m ɪ n i aɪ/) is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses.
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