Angiosperms

Angiosperms are a major division of plant life, constituting the majority of the Earth’s plants..

Angiosperm plants produce seeds enclosed in “fruits”, which include the fruits you eat, but also include plants you may not consider fruits, such as maple seeds, acorns, beans, wheat, rice and corn.

Angiosperms are also known as “flowering plants” because flowers are a characteristic part of their reproductive structure, although, again, you may not always recognise their flowers as the pretty, colourful, petalled things you think of when you hear the word.

Angiosperms evolved between 250 and 200 million years ago. They quickly gained an advantage over the likes of plant previously dominant, the gymnospermsfor two reasons.

The use of flowers by angiosperms to reproduce made them more reproductively successful. Whereas gymnosperms depended mainly on the wind to achieve reproduction. sexual reproduction through the transfer of pollenwhich contains the male reproductive cells of plants, to the ovaries of female plants, angiosperms used brightly coloured, sweet-smelling flowers and sugary nectar to attract insects and other animals.

This cooperative process, whereby animals such as bees pollinate flowers in exchange for nectar, made angiosperms more reproductively successful.

Angiosperms also began to enclose their seeds in fruits, which provided additional nutrition and protection for their offspring plants, and created new ways of cooperating with animals. Many angiosperm fruits, like their flowers, were designed to attract animals to eat them.

In many cases, the seeds would pass safely through the digestive tract of animals, being carried away from the parent plant in the process. The seeds would eventually be excreted in faecal matter, which, as an added bonus, is often very rich in plant nutrients. This allowed angiosperms to spread far and wide.

Today, angiosperms make up approximately 80% of all plant species on Earth.

Gymnosperms, which include pines, redwoods, gingko trees and palms, still occupy an important place in many ecosystems. But many gymnosperm species that lived in prehistoric forests are now extinct and have been replaced by angiosperms.

Anatomy of angiosperms

Scientists define angiosperms as plants that have several unique anatomical structures. These include:

• Stamens, which produce the pollen grains that act as spermatozoa for angiosperm plants. Pollen grains contain information genetics male and can be combined with female genetic information in the ovaries of plants.
  Some angiosperms can fertilise their ovaries with their own pollen or can reproduce without being fertilised at all. But plants, and organisms in general, that exchange genes through sexual reproduction tend to have more diverse offspring, which means their offspring are more likely to be able to resist disease, predation and natural disasters.
• Pollen, the male reproductive material of angiosperms, which is smaller than the male reproductive material of gymnosperms.
  This means that angiosperm male reproductive cells can reach female eggs faster and with higher success rates than gymnosperm reproductive cells.
• Flowers, which are structures containing the male and female reproductive parts of an angiosperm, and are often designed to attract insects and other animals that can cross-pollinate between different plants.
• Carpels, which enclose the ovaries found inside or just behind the flower of the plant. The ovaries can receive pollen grains and start producing seeds and fruits more quickly than gymnosperms can produce their own seeds.

If you look closely at the development of a plant, you can see that the base of the flower swells into fruit after pollination. This is the process of the carpel, which surrounds the ovary of the plant, turning into a fruit around the developing seeds.

In many fruits, the woody “spot” on the underside opposite the stem of the plant shows where the flower was attached before the carpel became a fruit.

Examples of angiosperms

Fruits

Fruit trees are perhaps the most obvious illustration of the angiosperm life cycle.

Fruit trees often display flowers, such as apple, cherry and orange trees, before they bear fruit. These flowers are pollinated by bees or other animals, which allows fruit trees to exchange genetic material and maintain their diversity. population.

Once the flowers have served their purpose of attracting pollinators, they lose their petals and the carpels at the base of the flower begin to swell. These carpels continue to grow until the fruit reaches full size and may change colour to better attract animals that want to eat it.

When birds or ground-dwelling animals eat the fruit of a tree, its seeds travel free wherever that animal goes, and free fertiliser, in the form of manure with which it is excreted.

Grains

It may seem strange to think of flowering plants as grasses, but they are in fact a member of the flowering plant family.

Grasses have moved away from their evolutionary origin of attracting animal pollinators with large, colourful flowers and fruits. Because grasses such as wheat and rice often grow in large numbers close together, they can rely on the wind to pollinate them and spread their seeds into the environment.

The versions of rice, maize and wheat that humans eat have seeds that could be described as “incredibly large”, because we have been selectively breeding our domestic crops to have the largest possible seeds for thousands of years.

As such, these domesticated plants often do not produce well without humans, because their seeds are too large to be carried by the wind. However, as long as humans are around, we will plant lots of them to feed ourselves!

In nature, grass seeds are much smaller and are easily spread by the wind.

Vegetables

The vegetables that come onto our plates have also been selectively bred by humans over many generations to make them as large and tasty as possible. As such, it may surprise you to learn that broccoli, kale and lettuce are flowering plants.

Broccoli, kale and lettuce that are to be eaten are usually harvested before they flower, as most humans do not consider flowers to be delicious. The tight green buds that make up broccoli plants are just that: little flower buds!

Farmers and gardeners will generally allow some of their green vegetables to flower and produce seeds, so that they can plant them for next year’s crop. But green vegetables intended to be eaten are usually harvested before their flowers appear.

Flowers

When it comes to flowers that were grown to be big and bright, your question might be “where on Earth does the fruit come in?”

The truth is that not all fruit looks like the big, colourful, sweet fruits we think of when we hear the term. In fact, a “fruit” is any protective coating around a seed, and the “fruits” of many plants can look like swollen seed pods.

Many flowers, including roses, lilies and daffodils, produce swollen green seed pods where the flowers used to be, after their petals fall off. If you walk through a daffodil garden after the flowers have lost their petals, you may see the stems “settle” as they become heavy with the weight of the developing fruit.

If you leave the seed pods on the stems long enough, they will eventually take on a dry appearance. Also, if you can shake the seed pod and hear the dry seeds rattling around inside, that means the seed maturation process is over and you can harvest the seeds to grow more daffodils next year.

The much touted “rosehips” that are sometimes used in food or medicinal preparations are actually the fruit of the rose plant.

• Plant: organism living organism that converts the energy from sunlight into fuel for cells through the process of photosynthesis. Plants are the basis of most ecosystem energy pyramids, as animals eat plants to absorb some of the energy they get from the sun.
• Seedseed: the reproductive unit of a plant, which includes the genetic material and nutrients necessary to initiate the development of a new plant.
• Symbiosis: a relationship between two organisms in which both benefit from each other. Cooperation between angiosperms and animals could be seen as an example of symbiosis.