Flowering plants are said to have evolved millions of years ago. It is believed that this group of plants originated in the landmass now known as South America and spread through other continents which was later on accompanied by animals like flies or beetles that carry pollen from one flower to another. After these flowering plants have been established, different species were created by natural selection and it led to the numerous types of flowers that we have today.
Flowering plants can be divided into three groups: monocots, dicots and magnoliids. Dicots are further subdivided into two groups, rosids and asterids based on a system developed by A. Cronquist in 1981. The major difference between these two groups is whether or not they have a single cotyledon (single leaf in the seed). Rosids have rose-like flowers and are often used for fruits, vegetables and herbs. On the other hand, asterids tend to have star-like flowers like daisies and sunflowers.
I know that some people don’t like knowing this, but flowering plants are actually categorized based on its fruits. Flowering plants with fleshy fruit (e.g., tomatoes) belong to the Kingdom of Plantae while those with dry fruits (e.g., peanuts) are under the Kingdom of Fungi.
Other examples of flowering plants include onions, tulips and gladiolas. Flowers can either be bisexual (have both male and female organs) or unisexual (male or female). Interestingly enough, some flowering plants are dioecious which means that male and female flowers grow on separate trees. This is the default way for some plants to reproduce. It is quite common in pines and oaks.
The basic unit of heredity in flowering plants are chromosomes which can be either duplicated or reduced depending on the type of plant wherein they come from. There are usually two versions, one parent has a chromosome while the other does not have it. This is to make sure that traits would still be passed on even if a chromosome is absent.
Flowering Plants and their Genetic Classes and Groups
What are the genetic classes and groups of flowering plants? In short, flower plants can either be diploid or polyploid. Polyploids mean that there are more than two sets of chromosomes in one organism. The structure of polyploids is different from diploid. There are two main groups of flowering plants: the monocots and the dicots.
The name originates from the Greek words ‘mono’ which means one and ‘cotyledon’ that refers to the single cotyledon. Monocots are one of the two largest families of flowering plants characterized by their narrow, parallel veins in leaves and its flowers having a single petal or none at all. Examples of monocots include lilies and palms. Notable examples of monocots with economic importance include corn, wheat, rice and barley
Sometimes referred to as dicotyledoneae, dicotyledons are flowering plants that come from the name ‘diktyon’ which means two-leaved. Since there is no single distinction between this family of flowering plant and its counterpart (monocots), they can be differentiated easily by its flowers which have 4 or 5 petals. The economic importance of dicotyledons include legumes, potatoes and cocoa trees.
The fruit of a flowering plant is divided into two general groups: Simple Fruits and Aggregate Fruits (or composite fruits). Baccatae known as berries are examples of simple fruits while ones like the orange represent an aggregate fruit composed of multiple flowers.
Drupes : These types of fruits look like stone-fruit and some resemble stone-fruits in terms of taste but they are indeed a type of drupe. Examples include plums, peaches and cherries.
Insects : Small insects develop inside the ovary after pollination . Some people might think that this fruit is an example of a berry but it is actually a false berry because the flower that produces this fruit are not connected with the ovary. Moreover, unlike the true berry, insects develop inside and feed on plants in order to get bigger to be protected from predators. Examples include raspberries and mulberries.
Aggregate Fruits : These types of fruits have masses of flowers that grow together forming a single structure. This type usually has multiple seeds within them too. Ex.: Grapes, strawberries, bananas
The evolutionary origin for flowering plants stems from ferns which date back as far as 390 million years ago wherein they were first believed to grow linked together much like conifers do today. Approximately 115 million years ago, the first true flowering plant came into existence when a group of ferns began to produce flowers with 2 separate petals. The original ancestor was still an undifferentiated hermaphroditic plant with all archegonia (female organs) and antheridia (male organs). It is believed that dioecious plants evolved around 110 million years ago while monoecious ones were thought to have appeared around 90 million years later.