A spikelet, in botany, describes the typical arrangement of the flowers of grasses, sedges and some other monocots.
Each spikelet has one or more florets. [1] : 12 The spikelets are further grouped into panicles or spikes. The part of the spikelet that bears the florets is called the rachilla . [1] : 13
In Poaceae, the grass family, a spikelet consists of two (or sometimes fewer) bracts at the base, called glumes, followed by one or more florets. [1] : 13 A floret consists of the flower surrounded by two bracts, one external—the lemma—and one internal—the palea. The perianth is reduced to two scales, called lodicules, [1] : 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. [2]
Lemma is a phytomorphological term referring to a part of the spikelet. It is the lowermost of two chaff-like bracts enclosing the grass floret. It often bears a long bristle called an awn, and may be similar in form to the glumes—chaffy bracts at the base of each spikelet. It is usually interpreted as a bract but it has also been interpreted as one remnant (the abaxial) of the three members of outer perianth whorl (the palea may represent the other two members, having been joined together).
A lemma's shape, their number of veins, whether they are awned or not, and the presence or absence of hairs are particularly important characters in grass taxonomy.
Palea, in Poaceae, refers to one of the bract-like organs in the spikelet.
The palea is the uppermost of the two chaff-like bracts that enclose the grass floret (the other being the lemma). It is often cleft at the tip, implying that it may be a double structure derived from the union of two separate organs. This has led to suggestions that it may be what remains of the grass sepals (outer perianth whorl): specifically the two adaxial members of the three membered whorl typical of monocots. The third member may be absent or it may be represented by the lemma, according to different botanical interpretations.
The perianth interpretation of the palea is supported by the expression of MADS-box genes in this organ during development, as is the case in sepals of eudicot plants. [3]
A lodicule is the structure that consists of between one and three small scales at the base of the ovary in a grass flower that represent the corolla, believed to be a rudimentary perianth. The swelling of the lodicules forces apart the flower's bracts, exposing the flower's reproductive organs.
A raceme or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the shoot grows in height, with no predetermined growth limit. Examples of racemes occur on mustard and radish plants.
A tepal is one of the outer parts of a flower. The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated, as in Magnolia, or because, although it is possible to distinguish an outer whorl of sepals from an inner whorl of petals, the sepals and petals have similar appearance to one another. The term was first proposed by Augustin Pyramus de Candolle in 1827 and was constructed by analogy with the terms "petal" and "sepal".
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture. Typically, they also look different from the parts of the flower, such as the petals or sepals. A plant having bracts is referred to as bracteate or bracteolate, while one that lacks them is referred to as ebracteate and ebracteolate, without bracts.
In botany, a glume is a bract below a spikelet in the inflorescence of grasses (Poaceae) or the flowers of sedges (Cyperaceae). There are two other types of bracts in the spikelets of grasses: the lemma and palea.
Sporobolus heterolepis, commonly known as prairie dropseed, is a species of prairie grass native to the tallgrass and mixed grass prairies of central North America from Texas to southern Canada. It is also found further east, to the Atlantic coast of the United States and Canada, but is much less common beyond the Great Plains and is restricted to specialized habitats. It is found in 27 states and four Canadian provinces.
Melica ciliata, the hairy melic or silky spike melic, is a species of flowering plant in the grass family Poaceae, native to Europe, north Africa and temperate Asia. It has been introduced to South Australia.
Melica animarum is a species of grass that is endemic to Sierra de las Ánimas in Uruguay.
Melica bonariensis is a species of grass endemic to Argentina where it can be found in such provinces as Buenos Aires, La Pampa, and Rio Negro.
Melica brasiliana, is a grass species in the family Poaceae that is endemic to Brazil and southern South America.
Melica bocquetii, is a species of grass in the family Poaceae that is endemic to the Subbaetic mountains of southern Spain.
Melica violacea, is a species of grass in the family Poaceae endemic to Chile.
Melica teneriffae, is a grass species in the family Poaceae that is endemic to the Canary Islands.
Melica spartinoides, is a species of grass in the family Poaceae that is endemic to the Brazilian state of Santa Catarina.
Melica serrana, is a species of grass endemic to Cerro de las Ánimas, Uruguay.
Melica stuckertii, is a grass species in the family Poaceae that is endemic to Argentina and southern South America.
Melica dendroides is a grass species in the family Poaceae that is endemic to southern part of Africa.
Melica minor is a species of grass in the family Poaceae. It is endemic to Caucasus.
Melica mollis is a species of grass endemic to Chile where it grows in rock crevices at 340 metres (1,120 ft) above sea level.
Melica penicillaris is a species of grass in the Poaceae family. It is endemic to Inner Anatolia, Turkey, where it grows on bushy hills, rocky slopes, limestone surfaces, and in gullies at 1,000–1,800 metres (3,300–5,900 ft) above sea level.
In botany, floral morphology is the study of the diversity of forms and structures presented by the flower, which, by definition, is a branch of limited growth that bears the modified leaves responsible for reproduction and protection of the gametes, called floral pieces.
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