Monocotyledon definition
Monocots, or monocots for short, refer to one of two groups of flowering plants called "angiosperms". Most flowering plants are traditionally divided into two different categories: monocots and dicots. Members of each group share similar characteristics.
Monocots, as the name suggests, are defined as seeds containing a single (mono)embryonic leaf called a cotyledon. This is a monophyletic group that makes up the majority of our agricultural biomass and includes many important staple crops, including rice, wheat, maize, sugarcane, bamboo, onions and garlic, among others.
One note: when classifying flowers as monocotyledonous or dicotyledonous, remember that there are always exceptions to the rule. Some monocotyledonous species may exhibit characteristics typical of dicotyledonous species and vice versa. Even a few flowering plants (about 2%) do not fit into either the monocotyledonous or dicotyledonous category.
Characteristics of monocotyledonous and dicotyledonous plants
Monocots differ from dicots in six different structural features. Five of these characteristics are readily apparent in a mature angiosperm: flowers, leaves, roots, stems, and pollen grains. However, the source of these differences lies in the very early embryonic stages of angiosperms, so the biggest difference between monocots and dicots is in the seeds.
Flowers
Flowers usually arrange their parts in a circle, with the reproductive parts surrounded by petals and sepals in the center. In monocots, these parts of the flower are trimeric. In other words, the floral parts of a monocot are arranged, textured, or numbered in more than three - typically with a stigma, three stamens, three petals, and a calyx made up of petals less than or equal to the number of petals.
Plahte
A vein is a pattern of veins on the underside of a leaf. These veins are responsible for transporting water and carbohydrates through the plant. In monocotyledonous plants, these veins are arranged in parallel. Compared to other vein systems, parallel veins in a parallel vein are smaller and are connected by even smaller veins.
source
While monocots start with a taproot, these taproots tend to die off soon after germination and are replaced by adventitious roots. Adventitious roots have a fibrous appearance and are widespread in the soil in many different directions. They usually occupy the topsoil and can be modified for various purposes, such as additional anchorage or air support. Since adventitious roots usually grow from an organ other than the root of the plant, such as a B. stem or sometimes a leaf, we can grow many plants from cuttings of the stems or leaves of an existing plant!
stems
It should be noted that the stems of monocotyledonous plants have lost the ability to increase in diameter by forming wood and bark as a result of secondary growth. Instead, the stems of monocotyledonous plants die each year, allowing a new stem to grow. The only point of growth of a monocot stem is the top of the stem, which prevents the growth of side shoots or branches. Monocots are usually small and herbaceous
On the cross-section of a monocotyledonous stem, you will find the epidermis, subcutaneous tissue, ground tissue and vascular bundles. Typically, monocotyledonous stems have the following characteristics: a single-layer cuticle with a thick cuticle; lack of epidermal hair; no concentric arrangement; subcutaneous tissue is sclerenchymal; the presence of a bundle sheath; oval vascular bundles of various sizes; and especially diffuse vascular bundles that do not form a pattern.
pollen grains
Monocots have a pollen structure preserved from the first angiosperms. The pollen grain of monocots is monosulfide, meaning that the pollen has a single furrow or pore in the outer layer.
germs
The plant embryo is the part of the seed that contains all the progenitor tissues of the plant and one or more cotyledons. As the name suggests, monocotyledonous plants are characterized by one (mono) stem in the seed and one leaf emerging from the stem. The seed pod of a monocot is also tripartite (consists of three parts) because the fruiting body from which it grew was also tripartite.
The cotyledon is the first part of the plant to emerge from the seed and is the true basis for distinguishing the two main groups of angiosperms. The cotyledons are important for nutrition and are responsible for absorbing nutrients from the environment until the plant is able to photosynthesise its own nutrients.
Examples of monocots
grass
While we don't generally think of grass as flowering plants, they actually have tiny flowers that grow to the very tops! The grass family is probably the most economically important group of monocots. Consider corn, wheat and rice - all types of grass whose flowers are often overlooked due to the lack of petals or tepals.
palma
The palm is an exception to the rule for monocots. Most monocots cannot grow as large and tall as palm trees because they lack the secondary growth—wood and bark growth—that allows most monocots to be purely herbaceous. However, palms have circumvented this problem by using their vascular bundles and the lignin they contain to create a stronger trunk. The trunks of the palms are also thickened with parenchyma cells surrounding the vascular bundles, providing even more support to the tall tree.
However, the leaf of the tree is the distinguishing feature of the palm that identifies it as a monocot. Palm leaves are long and strip-shaped, with the main veins running parallel to each other.
lily
Probably one of the easiest monocots to identify is the lily, as it has all the characteristics of a monocot. The flowers of most lilies are obvious and trimeric, as all three petals are usually identical in size and shape, the roots are adventitious, small and herbaceous, starting with a single cotyledon.
However, some lilies have developed different petal and flower structures, which can be confusing when classifying as monocotyledonous or dicotyledonous. Flowers can come in many different shapes, such as trumpets, funnels, cups, bells, and even flat shapes. For example, peace lily flowers grow in clusters on a stem called a spadix, which does not look like a typical flower cluster. A common misconception about the peace lily is that it has only one petal. What most people mistake for petals is actually a separate leaf called a spathe. True spadix flowers are actually trimmers.
orchids
Like the lily, the flower is a key feature of orchids that identifies them as monocots. Orchid flower petals are extremely trimer; However, certain morphological features distinguish orchids from other monocots. From the petals, which grow in threes, one petal has developed into a lip, a specialized landing platform for pollinators. Therefore, in orchids, not all three petals look the same, which can be confusing when looking for characteristics of monocots. Although the orchid begins with three stigmas, typical of most monocots, they later merge, with only a few faint lines indicating their trimeric structure.
banana
Often mistaken for a tree, the banana tree is actually a monocot and is closely related to the grass family. As with monocots, bananas have no secondary growth; They regularly die after the banana tree bears fruit. The banana fruit grows in groups of three (trifid, with three segments) and has leaves with the well-known pattern of parallel veins.
Quiz
1. How many embryonic cotyledons does a monocotyledon have?
A.How
B.two
C.tri
Answer to question number 1
AThat's good. As the name suggests, monocotyledonous plants have a (mono)embryonic cotyledon that emerges from the cotyledon. Dicots have two germinal seed leaves. Three embryonic seed leaves are not normally found, except in cases of genetic mutations seen in various self-fertile dicotyledonous plants.
2. The parts of a monocotyledon flower grow ______________ many times.
A.How
B.two
C.tri
D.four
Answer to question number 2
CThat's good. Monocot flowers are trimeric, meaning they grow in groups of three. Dicot flowers grow in groups of four or five. Flower parts do not grow singly in multiple pieces.
3. What type of root system do monocots usually NOT have?
A.Uterus
B.Fibrous roots
C.Adventivwurzeln
Answer to question number 3
AThat's good. Although monocots usually have a taproot, the taproot dies off soon after germination and is replaced by an adventitious root system.
reference
- Arecaceae. (2017, May 24). Retrieved May 25, 2017 from https://en.wikipedia.org/wiki/Arecaceae
- Banana. (2017, May 23). Retrieved May 25, 2017 from https://en.wikipedia.org/wiki/Banana
- Dodson, CH. (2017, January 31). Orchid. Retrieved May 25, 2017 from https://www.britannica.com/plant/orchid/Characteristic-morphological-features
- Haneef, D.T. (undated). main differences. Retrieved May 25, 2017 from http://www.majordifferences.com/2013/03/difference-between-dicot-and-monocot.html
- monocots. (2017, May 21). Retrieved May 25, 2017 from https://en.wikipedia.org/wiki/Monocotyledon
- Spathiphyllum. (2017, May 23). Retrieved May 25, 2017 from https://en.wikipedia.org/wiki/Spathiphyllum