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56-512: Palea may refer to: Palea (botany) , part of the flower structure in some plants Palea (turtle) , a genus of turtles in the family Trionychidae San Antonio de Palé , a town in Equatorial Guinea Palea (literature) , old Russian work of apocryphal content Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with

112-444: A phylogenetic tree to be constructed for the flowering plants. The establishment of major new clades necessitated a departure from the older but widely used classifications such as Cronquist and Thorne, based largely on morphology rather than genetic data. These developments complicated discussions on plant evolution and necessitated a major taxonomic restructuring. This DNA based molecular phylogenetic research confirmed on

168-408: A clade called "monocots" but does not assign it to a taxonomic rank. The monocotyledons include about 70,000 species, about a quarter of all angiosperms. The largest family in this group (and in the flowering plants as a whole) by number of species are the orchids (family Orchidaceae ), with more than 20,000 species. About 12,000 species belong to the true grasses ( Poaceae ), which are economically

224-719: A classification of flowering plants (florifera) based on a division by the number of cotyledons, but developed his ideas over successive publications, coining the terms Monocotyledones and Dicotyledones in 1703, in the revised version of his Methodus ( Methodus plantarum emendata ), as a primary method for dividing them, Herbae floriferae, dividi possunt, ut diximus, in Monocotyledones & Dicotyledones (Flowering plants, can be divided, as we have said, into Monocotyledons & Dicotyledons). Although Linnaeus (1707–1778) did not utilise Ray's discovery, basing his own classification solely on floral reproductive morphology ,

280-855: A diagnostic point of view the number of cotyledons is neither a particularly useful characteristic (as they are only present for a very short period in a plant's life), nor is it completely reliable. The single cotyledon is only one of a number of modifications of the body plan of the ancestral monocotyledons, whose adaptive advantages are poorly understood, but may have been related to adaption to aquatic habitats , prior to radiation to terrestrial habitats. Nevertheless, monocots are sufficiently distinctive that there has rarely been disagreement as to membership of this group, despite considerable diversity in terms of external morphology. However, morphological features that reliably characterise major clades are rare. Thus monocots are distinguishable from other angiosperms both in terms of their uniformity and diversity. On

336-438: A long bristle called an awn , and may be similar in form to the glumes , which are 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). The lemmas' shape, their number of veins, whether they are awned or not, and

392-573: A mixture of characteristics. Nymphaeaceae (water lilies) have reticulate veins, a single cotyledon, adventitious roots, and a monocot-like vascular bundle. These examples reflect their shared ancestry. Nevertheless, this list of traits is generally valid, especially when contrasting monocots with eudicots , rather than non-monocot flowering plants in general. Monocot apomorphies (characteristics derived during radiation rather than inherited from an ancestral form) include herbaceous habit, leaves with parallel venation and sheathed base, an embryo with

448-483: A proximal leaf base or hypophyll and a distal hyperphyll. In monocots the hypophyll tends to be the dominant part in contrast to other angiosperms. From these, considerable diversity arises. Mature monocot leaves are generally narrow and linear, forming a sheathing around the stem at its base, although there are many exceptions. Leaf venation is of the striate type, mainly arcuate-striate or longitudinally striate (parallel), less often palmate-striate or pinnate-striate with

504-582: A short axial body bearing leaves whose bases store food. Additional outer non-storage leaves may form a protective function (Tillich, Figure 12). Other storage organs may be tubers or corms , swollen axes. Tubers may form at the end of underground runners and persist. Corms are short lived vertical shoots with terminal inflorescences and shrivel once flowering has occurred. However, intermediate forms may occur such as in Crocosmia (Asparagales). Some monocots may also produce shoots that grow directly down into

560-617: A similar position as a major division of the flowering plants throughout the nineteenth century, with minor variations. George Bentham and Hooker (1862–1883) used Monocotyledones, as would Wettstein , while August Eichler used Mononocotyleae and Engler , following de Candolle, Monocotyledoneae. In the twentieth century, some authors used alternative names such as Bessey 's (1915) Alternifoliae and Cronquist 's (1966) Liliatae. Later (1981) Cronquist changed Liliatae to Liliopsida, usages also adopted by Takhtajan simultaneously. Thorne (1992) and Dahlgren (1985) also used Liliidae as

616-425: A single cotyledon, an atactostele , numerous adventitious roots, sympodial growth, and trimerous (3 parts per whorl ) flowers that are pentacyclic (5 whorled) with 3 sepals, 3 petals, 2 whorls of 3 stamens each, and 3 carpels. In contrast, monosulcate pollen is considered an ancestral trait, probably plesiomorphic . The distinctive features of the monocots have contributed to the relative taxonomic stability of

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672-401: A smaller group were grass-like plants with long straight parallel veins. In doing so he distinguished between the dicotyledons, and the latter (grass-like) monocotyledon group, although he had no formal names for the two groups. Formal description dates from John Ray 's studies of seed structure in the 17th century. Ray, who is often considered the first botanical systematist , observed

728-686: A synonym. Taxonomists had considerable latitude in naming this group, as the Monocotyledons were a group above the rank of family. Article 16 of the ICBN allows either a descriptive botanical name or a name formed from the name of an included family. In summary they have been variously named, as follows: Over the 1980s, a more general review of the classification of angiosperms was undertaken. The 1990s saw considerable progress in plant phylogenetics and cladistic theory, initially based on rbcL gene sequencing and cladistic analysis, enabling

784-509: A typical inverted conical shape of the basal primary axis ( see Tillich, Figure 1). The limited conductivity also contributes to limited branching of the stems. Despite these limitations a wide variety of adaptive growth forms has resulted (Tillich, Figure 2) from epiphytic orchids (Asparagales) and bromeliads (Poales) to submarine Alismatales (including the reduced Lemnoideae ) and mycotrophic Burmanniaceae (Dioscreales) and Triuridaceae (Pandanales). Other forms of adaptation include

840-466: Is a broad sketch only, not invariably applicable, as there are a number of exceptions. The differences indicated are more true for monocots versus eudicots . A number of these differences are not unique to the monocots, and, while still useful, no one single feature will infallibly identify a plant as a monocot. For example, trimerous flowers and monosulcate pollen are also found in magnoliids , and exclusively adventitious roots are found in some of

896-499: Is the name that has been most commonly used since the publication of the Angiosperm Phylogeny Group (APG) system in 1998 and regularly updated since. Within the angiosperms, there are two major grades , a small early branching basal grade, the basal angiosperms (ANA grade) with three lineages and a larger late branching grade, the core angiosperms (mesangiosperms) with five lineages, as shown in

952-539: 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. Monocot Monocotyledons ( / ˌ m ɒ n ə ˌ k ɒ t ə ˈ l iː d ə n z / ), commonly referred to as monocots , ( Lilianae sensu Chase & Reveal) are grass and grass-like flowering plants (angiosperms),

1008-759: Is their growth pattern, lacking a lateral meristem ( cambium ) that allows for continual growth in diameter with height ( secondary growth ), and therefore this characteristic is a basic limitation in shoot construction. Although largely herbaceous, some arboraceous monocots reach great height, length and mass. The latter include agaves , palms , pandans , and bamboos . This creates challenges in water transport that monocots deal with in various ways. Some, such as species of Yucca , develop anomalous secondary growth, while palm trees utilise an anomalous primary growth form described as establishment growth ( see Vascular system ). The axis undergoes primary thickening, that progresses from internode to internode, resulting in

1064-683: Is usually fugacious (short lived). Some of the more persistent perigones demonstrate thermonastic opening and closing (responsive to changes in temperature). About two thirds of monocots are zoophilous , predominantly by insects . These plants need to advertise to pollinators and do so by way of phaneranthous (showy) flowers. Such optical signalling is usually a function of the tepal whorls but may also be provided by semaphylls (other structures such as filaments , staminodes or stylodia which have become modified to attract pollinators). However, some monocot plants may have aphananthous (inconspicuous) flowers and still be pollinated by animals. In these

1120-721: Is whose pulp is divided into two lobes and a radicle... 2. Such which neither spring out of the ground with seed leaves nor have their pulp divided into lobes John Ray (1674), pp. 164, 166 Since this paper appeared a year before the publication of Malpighi 's Anatome Plantarum (1675–1679), Ray has the priority. At the time, Ray did not fully realise the importance of his discovery but progressively developed this over successive publications. And since these were in Latin, "seed leaves" became folia seminalia and then cotyledon , following Malpighi . Malpighi and Ray were familiar with each other's work, and Malpighi in describing

1176-593: The Piperaceae . Similarly, at least one of these traits, parallel leaf veins, is far from universal among the monocots. Broad leaves and reticulate leaf veins, features typical of dicots, are found in a wide variety of monocot families: for example, Trillium , Smilax (greenbriar), Pogonia (an orchid), and the Dioscoreales (yams). Potamogeton and Paris quadrifolia (herb-paris) are examples of monocots with tetramerous flowers. Other plants exhibit

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1232-450: The cladogram . Amborellales Nymphaeales Austrobaileyales magnoliids Chloranthales monocots Ceratophyllales eudicots While the monocotyledons have remained extremely stable in their outer borders as a well-defined and coherent monophylectic group, the deeper internal relationships have undergone considerable flux, with many competing classification systems over time. Historically, Bentham (1877), considered

1288-537: The dichotomy of cotyledon structure in his examination of seeds. He reported his findings in a paper read to the Royal Society on 17 December 1674, entitled "A Discourse on the Seeds of Plants". The greatest number of plants that come of seed spring at first out of the earth with two leaves which being for the most part of a different figure from the succeeding leaves are by our gardeners not improperly called

1344-440: The eudicots are the largest and most diversified angiosperm radiations , accounting for 22.8% and 74.2% of all angiosperm species respectively. Of these, the grass family (Poaceae) is the most economically important, which together with the orchids Orchidaceae account for half of the species diversity, accounting for 34% and 17% of all monocots respectively, and are among the largest families of angiosperms. They are also among

1400-530: The lilioid monocots ; major cereal grains ( maize , rice , barley , rye , oats , millet , sorghum and wheat ) in the grass family ; and forage grasses ( Poales ) as well as woody tree-like palm trees ( Arecales ), bamboo , reeds and bromeliads (Poales), bananas and ginger ( Zingiberales ) in the commelinid monocots , as well as both emergent (Poales, Acorales ) and aroids , as well as floating or submerged aquatic plants such as seagrass ( Alismatales ). The most important distinction

1456-418: The phyletic system that superseded it in the late nineteenth century, based on an understanding of the acquisition of characteristics. He also made the crucial observation Ex hac seminum divisione sumum potest generalis plantarum distinctio, eaque meo judicio omnium prima et longe optima, in eas sci. quae plantula seminali sunt bifolia aut διλόβω, et quae plantula sem. adulta analoga. (From this division of

1512-463: The seeds of which typically contain only one embryonic leaf, or cotyledon . They constitute one of the major groups into which the flowering plants have traditionally been divided; the rest of the flowering plants have two cotyledons and were classified as dicotyledons , or dicots. Monocotyledons have almost always been recognized as a group, but with various taxonomic ranks and under several different names. The APG III system of 2009 recognises

1568-471: The suffix -florae was replaced with -anae ( e.g. Alismatanae ) and the number of superorders expanded to ten with the addition of Bromelianae, Cyclanthanae and Pandananae. Molecular studies have both confirmed the monophyly of the monocots and helped elucidate relationships within this group. The APG system does not assign the monocots to a taxonomic rank, instead recognizing a monocots clade. However, there has remained some uncertainty regarding

1624-733: The ability to increase the width of a stem ( secondary growth ) via the same kind of vascular cambium found in non-monocot woody plants . However, some monocots do have secondary growth; because this does not arise from a single vascular cambium producing xylem inwards and phloem outwards, it is termed "anomalous secondary growth". Examples of large monocots which either exhibit secondary growth, or can reach large sizes without it, are palms ( Arecaceae ), screwpines ( Pandanaceae ), bananas ( Musaceae ), Yucca , Aloe , Dracaena , and Cordyline . The monocots form one of five major lineages of mesangiosperms (core angiosperms), which in themselves form 99.95% of all angiosperms . The monocots and

1680-462: The angiosperms. Correlation with morphological criteria showed that the defining feature was not cotyledon number but the separation of angiosperms into two major pollen types, uniaperturate ( monosulcate and monosulcate-derived) and triaperturate (tricolpate and tricolpate-derived), with the monocots situated within the uniaperturate groups. The formal taxonomic ranking of Monoctyledons thus became replaced with monocots as an informal clade. This

1736-421: The climbing vines of Araceae (Alismatales) which use negative phototropism ( skototropism ) to locate host trees ( i.e. the darkest area), while some palms such as Calamus manan ( Arecales ) produce the longest shoots in the plant kingdom, up to 185 m long. Other monocots, particularly Poales , have adopted a therophyte life form . The cotyledon, the primordial Angiosperm leaf consists of

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1792-484: The cotyledons were critical to the development of the plant, proof that Ray required for his theory. In his Methodus plantarum nova Ray also developed and justified the "natural" or pre-evolutionary approach to classification, based on characteristics selected a posteriori in order to group together taxa that have the greatest number of shared characteristics. This approach, also referred to as polythetic would last till evolutionary theory enabled Eichler to develop

1848-404: The dominant members of many plant communities. The monocots are one of the major divisions of the flowering plants or angiosperms. They have been recognized as a natural group since the sixteenth century when Lobelius (1571), searching for a characteristic to group plants by, decided on leaf form and their venation . He observed that the majority had broad leaves with net-like venation, but

1904-419: The exact relationships between the major lineages, with a number of competing models (including APG). The APG system establishes eleven orders of monocots. These form three grades, the alismatid monocots , lilioid monocots and the commelinid monocots by order of branching, from early to late. In the following cladogram numbers indicate crown group (most recent common ancestor of the sampled species of

1960-437: 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. A lodicule

2016-423: The group. Douglas E. Soltis and others identify thirteen synapomorphies (shared characteristics that unite monophyletic groups of taxa); Monocots have a distinctive arrangement of vascular tissue known as an atactostele in which the vascular tissue is scattered rather than arranged in concentric rings. Collenchyma is absent in monocot stems, roots and leaves. Many monocots are herbaceous and do not have

2072-464: The leaf veins emerging at the leaf base and then running together at the apices. There is usually only one leaf per node because the leaf base encompasses more than half the circumference. The evolution of this monocot characteristic has been attributed to developmental differences in early zonal differentiation rather than meristem activity (leaf base theory). The lack of cambium in the primary root limits its ability to grow sufficiently to maintain

2128-428: 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. 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 . The lemma often bears

2184-419: The monocots to consist of four alliances , Epigynae, Coronariae, Nudiflorae and Glumales, based on floral characteristics. He describes the attempts to subdivide the group since the days of Lindley as largely unsuccessful. Like most subsequent classification systems it failed to distinguish between two major orders, Liliales and Asparagales , now recognised as quite separate. A major advance in this respect

2240-405: The most important family of monocotyledons. Often mistaken for grasses, sedges are also monocots. In agriculture the majority of the biomass produced comes from monocotyledons. These include not only major grains ( rice , wheat , maize , etc.), but also forage grasses, sugar cane , the bamboos , and many other common food and decorative crops. The monocots or monocotyledons have, as

2296-411: The name implies, a single (mono-) cotyledon , or embryonic leaf, in their seeds . Historically, this feature was used to contrast the monocots with the dicotyledons or dicots which typically have two cotyledons; however, modern research has shown that the dicots are not a natural group, and the term can only be used to indicate all angiosperms that are not monocots and is used in that respect here. From

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2352-400: The one hand that the monocots remained as a well defined monophyletic group or clade , in contrast to the other historical divisions of the flowering plants, which had to be substantially reorganized. No longer could the angiosperms be simply divided into monocotyledons and dicotyledons; it was apparent that the monocotyledons were but one of a relatively large number of defined groups within

2408-520: The one hand, the organization of the shoots, leaf structure, and floral configuration are more uniform than in the remaining angiosperms, yet within these constraints a wealth of diversity exists, indicating a high degree of evolutionary success. Monocot diversity includes perennial geophytes such as ornamental flowers including orchids ( Asparagales ); tulips and lilies ( Liliales ); rosette and succulent epiphytes (Asparagales); mycoheterotrophs (Liliales, Dioscoreales , Pandanales ), all in

2464-511: The plant. This necessitates early development of roots derived from the shoot (adventitious roots). In addition to roots, monocots develop runners and rhizomes , which are creeping shoots. Runners serve vegetative propagation , have elongated internodes , run on or just below the surface of the soil and in most case bear scale leaves . Rhizomes frequently have an additional storage function and rhizome producing plants are considered geophytes (Tillich, Figure 11). Other geophytes develop bulbs ,

2520-535: The plants rely either on chemical attraction or other structures such as coloured bracts fulfill the role of optical attraction. In some phaneranthous plants such structures may reinforce floral structures. The production of fragrances for olfactory signalling are common in monocots. The perigone also functions as a landing platform for pollinating insects. The embryo consists of a single cotyledon, usually with two vascular bundles . The traditionally listed differences between monocots and dicots are as follows. This

2576-528: 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

2632-482: The same structures had introduced the term cotyledon, which Ray adopted in his subsequent writing. Mense quoque Maii, alias seminales plantulas Fabarum, & Phaseolorum, ablatis pariter binis seminalibus foliis, seu cotyledonibus, incubandas posui In the month of May, also, I incubated two seed plants, Faba and Phaseolus , after removing the two seed leaves, or cotyledons Marcello Malpighi (1679), p. 18 In this experiment, Malpighi also showed that

2688-425: The seed leaves... In the first kind the seed leaves are nothing but the two lobes of the seed having their plain sides clapt together like the two halves of a walnut and therefore are of the just figure of the seed slit in sunder flat wise... Of seeds that spring out of the earth with leaves like the succeeding and no seed leaves I have observed two sorts. 1. Such as are congenerous to the first kind precedent that

2744-400: The seeds derives a general distinction amongst plants, that in my judgement is first and by far the best, into those seed plants which are bifoliate, or bilobed, and those that are analogous to the adult), that is between monocots and dicots. He illustrated this by quoting from Malpighi and including reproductions of Malpighi's drawings of cotyledons (see figure). Initially Ray did not develop

2800-445: The soil, these are geophilous shoots (Tillich, Figure 11) that help overcome the limited trunk stability of large woody monocots. In nearly all cases the perigone consists of two alternating trimerous whorls of tepals , being homochlamydeous , without differentiation between calyx and corolla . In zoophilous (pollinated by animals) taxa, both whorls are corolline (petal-like). Anthesis (the period of flower opening)

2856-403: The specific issue regarding Liliales and Asparagales, Dahlgren followed Huber (1969) in adopting a splitter approach, in contrast to the longstanding tendency to view Liliaceae as a very broad sensu lato family . Following Dahlgren's untimely death in 1987, his work was continued by his widow, Gertrud Dahlgren , who published a revised version of the classification in 1989. In this scheme

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2912-438: The spikelet that bears the florets is called the rachilla . 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. 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 , that expand and contract to spread

2968-490: The term was used shortly after his classification appeared (1753) by Scopoli and who is credited for its introduction. Every taxonomist since then, starting with De Jussieu and De Candolle , has used Ray's distinction as a major classification characteristic. In De Jussieu's system (1789), he followed Ray, arranging his Monocotyledones into three classes based on stamen position and placing them between Acotyledones and Dicotyledones. De Candolle's system (1813) which

3024-561: The title Palea . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Palea&oldid=1082835379 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Palea (botany) Each spikelet has one or more florets . The spikelets are further grouped into panicles or spikes . The part of

3080-559: Was the work of Rolf Dahlgren (1980), which would form the basis of the Angiosperm Phylogeny Group 's (APG) subsequent modern classification of monocot families. Dahlgren who used the alternate name Lilliidae considered the monocots as a subclass of angiosperms characterised by a single cotyledon and the presence of triangular protein bodies in the sieve tube plastids . He divided the monocots into seven superorders , Alismatiflorae, Ariflorae, Triuridiflorae, Liliiflorae , Zingiberiflorae, Commeliniflorae and Areciflorae. With respect to

3136-468: Was to predominate thinking through much of the 19th century used a similar general arrangement, with two subgroups of his Monocotylédonés (Monocotyledoneae). Lindley (1830) followed De Candolle in using the terms Monocotyledon and Endogenae interchangeably. They considered the monocotyledons to be a group of vascular plants ( Vasculares ) whose vascular bundles were thought to arise from within ( Endogènes or endogenous ). Monocotyledons remained in

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