Angiosperms are basically divided into two large groups: the monocots and eudicots. Monocots constitute a monophyletic group, that is, a group in which all species share a common ancestor. This monophyly is supported by the presence of several synapomorphies and by nuclear and chloroplast DNA sequences.
Monocots are pherbaceous lanterns usually no secondary growth and with parallel veneration sheets and sheath. It is important to note that many species, however, have leaves with peninerveal venation or webbed, which many authors consider as a reversal associated with the shaded habitat.
Note the presence of only one cotyledon (arrow) in the corn seed
In addition to these characteristics, in monocots, the embryo has a single cotyledon. This structure is nothing more than a modified leaf that has the function of accumulating nutrients for the embryo, thus ensuring seed germination. In eudicots, unlike this group of plants, there are two cotyledons.
Observe the randomly distributed bundles on the stem of monocots
Another characteristic of monocots is the presence of vascular bundles distributed randomly in the stem. This peculiarity allows them to be distinguished from eudicots, which have vascular bundles arranged in rings, delimiting the medulla.
The flowers of monocotyledons are generally pentacyclic and trimeral and have mono-grooved pollen. This type of pollen has only one opening in its outer layer, called exine.
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The orders of monocots according to the APG III are listed below:
- Acorales – Includes the Acoraceae family, probably the sister group of the other monocots.
- Alismatales – Contains about 14 families, including Araceae, the calla lily family.
- Asparagales – This order contains about 14 families. It can be highlighted the Orchidaceae, the family of orchids.
- Liliales – They include 11 families, highlighting Liliaceae, the tulip family.
- Petrosaviales – Include only the Petrosaviaceae family.
- Dioscoreales – They have three families, especially Dioscoreaceae, the yam family.
- Pandanales – This order has five families, highlighting the Velloziaceae family.
- Arecales – Include only the Arecaceae family, the palm family.
- Commelinales – They include five families, among them the Commelinaceae, the family of spider pods.
- Poales – This order includes 17 families, especially Poaceae, the grass family.
- Zingiberales – Contains eight families, highlighting the Zingiberaceae, the ginger family.
By Ma. Vanessa dos Santos
Would you like to reference this text in a school or academic work? Look:
SANTOS, Vanessa Sardinha dos. "Monocots"; Brazil School. Available in: https://brasilescola.uol.com.br/biologia/monocotiledoneas.htm. Accessed on June 28, 2021.
