Introduction to Flowering plants
There are a lot of plants in the world that botanists have taken to classifying them, just so it’s quite simpler to study them. Firstly, the plants are categorized based on the presence or absence of flowers. We can break the flowering plants into two basic groups based on their physical appearance and the number of leaves developed.
Cotyledons are an important component of the embryo present in a seed. All plants are categorized as the presence or absence of seeds. Furthermore, those plants that possess seeds are sub-divided into flowering (angiosperms) and non-flowering (gymnosperms) plants. Flowering plants, then split into monocots and dicots.
Monocotyledons (often called monocots) are flowering plants whose seeds normally possess just one embryonic cotyledon.
- There are almost 60,000 species of the monocots.
- Monocots are predominantly herbaceous.
- They derive their name from the composition of the seeds, which have one cotyledon, situated at the end.
Monocotyledons are present in diverse habitats, most commonly in tropical areas. Although they are found in large numbers in the tropic areas, many species can be present in many other areas as well – i.e. in ponds, rivers, lakes and coastal aquatic environments, in barren lands, and even in the polar habitats. Monocots do not usually develop into trees, because they lack any particular woody tissue.
Characteristics of the monocot plant
The flower parts of monocotyledon are properly organized, structured, or arranged in multiples of three—mostly with one stigma and calyx, three stamens and petals.
The seed contains only a single cotyledon.
Leaves of monocots are usually isobilateral i.e. both sides look the same and are basically the same; both are directed towards the sun (mostly vertically aligned). The leaves are very thin with parallel venation, plane edge, an elongated sheath, always wrapping the stem. The leaves are fixed i.e. clearly connected to its base (without a stalk). But a few monocots are still believed to have netted veins, like Smilax.
Monocots are mostly considered as herbaceous, which means they have delicate, green stem and are not arboraceous(woody). The stems of monocots are mostly branchless and soft. Vascular tissue arranged in elongated chains referred to as vascular bundles. In monocots, these bundles are widely dispersed throughout the broad cross-section of the stem., with more of the bundles positioned toward the edge of the stem rather than in the middle. This pattern is unusual to monocots.
Roots can originate either from a primary radicle or come up in groups from the nodes in the stem, known as adventitious roots. Monocots are known to have adventitious roots. The roots of a monocot do not have a vascular cambium (the region of secondary vascular tissue growth) and therefore lack secondary thickening.
Corn, rice, sugarcane, sorghum, ginger, orchid, Onion, garlic, banana, coconut, palm, tulips, lilies, daffodils etc.
Comparison chart between monocots and dicots
|Sr. No||Basis of Comparison||Monocot seeds||Dicot seeds|
|1||Definition||Monocots are those flowering plants that contain a single seed leaf inside the seed coat.||Dicotyledons are members of angiosperms containing seeds with a pair of cotyledons.|
|2||Root||Monocots own a fibrous root system.||They possess a tap root system. Nevertheless, a few dicots might also own adventitious root system.|
|3||Pollen –grains||The pollen grains in monocots specifically have a single ridge or hole.||The pollen grains in dicot plants are tricolpate, as they have three clefts that go through the external layer.|
|4||Germination||When germination takes place in monocot seeds, it usually gives rise to only one leaf. It is mostly elongated and tapered, just like the adult leaf. The seed germination here is most often, hypogeal.||When a dicot seed germinates, it brings about a pair of seed leaves. They preserve the nutrients for the young plant, so they are normally bulkier than the true leaves. The seed germination here can be both, hypogeal or epigeal.|
|5||Stems||The stems of monocotyledons are herbaceous, branchless and delicate. They lack cambium and cannot enlarge in diameter.||They contain either herbaceous or arboraceous stems. The cambium is present and they are capable to enlarge in diameter.|
|6||Pollen tube||The pollen tube in monocot seeds it possesses only one pore.||There may be three or more than three pores in pollen tube of dicot seeds.|
|7||Flower parts||The monocot flowers are mostly trimerous i.e. the parts of flowers are arranged in multiples of three or equal to three.||The dicot flowers are either tetramerous or pentamerous i.e. flower parts are organized in multiples of four or five.|
|8||Secondary growth||Due to the deprivation of cambium, monocots do not experience secondary growth.||Dicots can undergo secondary growth as they possess lateral meristem or cambium.|
Dicotyledon also referred to as dicot, are a type of the flowering plants, or angiosperms, that contains two cotyledons, in the seed embryo.
- There are approximately 175,000 familiar species of dicots.
When you take a look out of the window of your house, nearly every plant is dicot plants. Most familiar plants that can be observed in our surroundings like an oak tree, roses and cactus etc are dicots.
Characteristics of dicots
Here are a few characteristics that describe dicotyledonous plants.
The dicots are characterized by the existence of two collateral cotyledons in every seed. The seed leaves are mostly ring-shaped and bulky, as they are the two halves of the seed.
The leaves can be complicated or uncomplicated, with the dorsoventral arrangement. They come up with net or reticulate venation and are usually with irregular boundaries, rough or dissected.
The stems are solid with vascular bundles present in a form of a circle that comprises of two structures, the xylem, and the phloem. The xylem assists in carrying water and minerals from the root to the many other parts of the plant. The phloem conveys food that is prepared inside the leaves, to the storage areas. The number of xylem and phloem varies from 2-4 and they are differentiated by a sheet of parenchymatous cells known as conjunctive tissue.
These plants contain a tap root system. They possess two parts:
- The external epidermis which often forms root hair
- The internal endodermis.
In the majority of dicots, the root emerges from the bottom end of the embryo, from an area called the radicle. It brings about an apical meristem which constantly generates root tissue. Root systems usually perform the following functions:
- Intake of water and organic substances
- Fixing the plant body to the soil
- A storehouse of food and nutrients
In dicot plants, flowers are mostly pentamerous i.e. they are present in multiples of four or five. This character is not always authentic, however, and is not so simple to use in those flowers with lesser or multiple parts. These flower parts comprise petals, sepals, and pistils, and the reproductive component of the plant.
Roses, oak trees, daisies, peas, beans, cactus, magnolia, marigolds, sunflowers, buttercups, asters, dandelions, etc.