- Byname:
- monocot
- Key People:
- Agnes Arber
- Related Topics:
- Asparagales
- Alismatales
- Pandanales
- Liliales
- commelinid
monocotyledon
-
What is a monocotyledon plant?
Monocotyledons, also known as monocots, are one of the two major groups of flowering plants (angiosperms). Approximately 60,000 species of monocots exist, including the most economically important plant family, Poaceae (true grasses), and the largest of all plant families, Orchidaceae (orchids).
Monocots are characterized by seeds with a single cotyledon, leaves with parallel veins, scattered vascular bundles in the stem, the absence of typical cambium, and an adventitious root system. Flower parts typically come in multiples of three, and the pollen grains characteristically feature a single aperture (or furrow).
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How are monocotyledon plants different from dicotyledon plants?
Monocotyledons (monocots) and eudicotyledons (eudicots) are the two main groups of angiosperms (flowering plants). Monocots are marked by key characteristics that generally distinguish them from eudicots.
Monocots:
* Feature one seed leaf, or cotyledon, in the embryo
* Have leaves with parallel veins
* Contain scattered vascular bundles in the stem
* Lack a typical cambium
* Possess an adventitious root system
* Typically have flower parts in multiples of three
* Feature pollen grains with one aperture or furrowIn contrast, eudicots typically have two cotyledons. Also, the vascular system of monocots consists of scattered vascular bundles, while eudicots feature vascular tissues surrounding a central pith.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What does the word 'monocotyledon' mean?
A monocotyledon, also known as a monocot, is a plant whose embryo has only one cotyledon, or seed leaf. Monocots are one of the two major groups of flowering plants, or angiosperms; the other group is the eudicotyledons (eudicots).
Other characteristics of monocots:
* Leaves with parallel veins
* Scattered vascular bundles in the stem
* Absence of cambium
* Adventitious root system
* Flower parts in multiples of three
* Pollen grains featuring a single aperture3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are some common examples of monocotyledon plants?
Monocotyledons are a major group of flowering plants with approximately 60,000 species. They are characterized by having only one seed leaf, or cotyledon, in the embryo.
Some common examples of monocot plants include members of the Poaceae (true grasses), Orchidaceae (orchids), Liliaceae (lilies), Arecaceae (palms), and Iridaceae (irises) families. Monocots typically have flower parts in multiples of three and parallel-veined leaves.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How do the leaves, stems, and roots of monocots usually look?
Monocot leaves typically lack a petiole and have parallel veins running longitudinally without a midvein. Monocot stems have scattered vascular bundles, without a pith or cortex, and they rarely have secondary growth. Monocots typically feature a fibrous root system, characterized by a mass of roots of roughly equal diameter emerging from the stem base. This contrasts with the taproot system found in dicots.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Why are monocotyledon plants important in agriculture and everyday life?
Monocotyledons, or monocots, are vital in agriculture and everyday life, with around 60,000 species, including some of the most economically important plants.
The Poaceae family, or true grasses, are monocots and a staple food source. Major monocot crops include barley, sorghum, maize, rice, and wheat. Other prominent monocot families include Liliaceae (lilies), Arecaceae (palms), and Iridaceae (irises).
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
monocotyledon, one of the two great groups of flowering plants, or angiosperms, the other being the eudicotyledons (eudicots). There are approximately 60,000 species of monocots, including the most economically important of all plant families, Poaceae (true grasses), and the largest of all plant families, Orchidaceae (orchids). Other prominent monocot families include Liliaceae (lilies), Arecaceae (palms), and Iridaceae (irises). Most of them are distinguished by the presence of only one seed leaf, or cotyledon, in the embryo contained in the seed. Eudicotyledons, in contrast, ordinarily have two cotyledons.
Evolution
Monocots form a monophyletic group, meaning that they share a common evolutionary history. It is widely believed that the monocots were derived from primitive eudicots. Given that the various physical features of monocots are regarded as derived characteristics within the angiosperms, any plant more primitive than the monocots in these several respects would certainly be a eudicot. Some of the earliest known monocot fossils are pollen grains dating to the Aptian Age of the Early Cretaceous Epoch (125 millionā113 million years ago). Molecular clock studies (which employ differences in DNA to estimate when a group split from its ancestors) suggest that monocots may have originated as early as 140 million years ago.
Evolutionary diversification among the monocotyledons appears to have been constrained by a number of fundamental features of the group, most notably the absence of a typical vascular cambium and the parallel-veined rather than net-veined leaves. Within these constraints, the monocots show a wide range of diversity of structure and habitat. They are cosmopolitan in their distribution on land. They also grow in lakes, ponds, and rivers, sometimes free-floating but more often rooted to the bottom. Some of them grow in the intertidal zone along the seashore, and a few are submerged marine plants rooted to the bottom in fairly shallow water along the shore.
" height="20" alt="HEW Logo">
Physical characteristics
Monocot plants are marked by seeds with a single cotyledon, parallel-veined leaves, scattered vascular bundles in the stem, the absence of a typical cambium, and an adventitious root system. Flower parts typically come in multiples of three, and the pollen grains characteristically feature a single aperture (or furrow).
The roots of a monocot lack a vascular cambium (the area of secondary xylem and phloem, or secondary vascular tissue, development) and therefore have no means of secondary thickening. In other structural respects, monocot roots are essentially similar to those of eudicots. Many eudicots have a taproot or several strong roots, with several orders of branch roots, all originating eventually from the embryonic root (radicle). The taproot or primary roots in such a system have a vascular cambium and are thickened by secondary growth. This kind of root system is not available to monocots. Instead, the primary root that originates from the radicle of the embryo soon aborts or is undeveloped so that no primary root is produced. The root system of monocots is thus wholly adventitiousāi.e., the roots originate laterally from the stem or from the hypocotyl (the region of transition between the root and the stem in the embryo). The roots are all slender, and the plant is said to be fibrous-rooted.
Flowers of monocots differ from those of eudicots mainly in the number of parts of each kind. Monocot flowers most often have the parts in sets of three, occasionally four, but almost never five. The numbers are especially characteristic of the sepals and petals. The stamens and pistils may be numerous even when the perianth is trimerous (in sets of three), or the single ovary may have only two carpels instead of three. Often there are six stamens, representing two whorls of three.