Angiosperms, or
flowering plants, are the most numerous of all the divisions in the Plant
Kingdom. With the exception of extreme habitats, angiosperms populate every
land biome and aquatic community. They are a major food source for animals and
humans, and are a major economic source for the production of various
commercial products.
Flowering Plant Parts
The parts of a
flowering plant are characterized by two basic systems: a root system and a
shoot system.
The root system is
typically below ground and serves to acquire nutrients and anchor the plant in
the soil. The shoot system consists of the stems, leaves, and flowers. These
two systems are connected by vascular tissue. Vascular tissues called xylem and
phloem are composed of specialized plant cells that run from the root through
the shoot. They transport water and nutrients throughout the plant.
Leaves are an important
component of the shoot system as they are the structures through which plants
acquire nutrition by photosynthesis. Leaves contain organelles called
chloroplasts that are the sites of photosynthesis. Gas exchange needed for
photosynthesis occurs through the opening and closing of tiny leaf pores called
stomata. The ability of angiosperms to shed their foliage helps the plant to
conserve energy and reduce water loss during cold, dry months.
The flower, also a
component of the shoot system, is responsible for seed development and
reproduction.
There are four main
flower parts in angiosperms: sepals, petals, stamens, and carpels. After pollination,
the plant carpel develops into fruit. Both flowers and fruit are often colorful
in order to attract pollinators and animals that eat fruit. As the fruit is
consumed, the seeds pass through the animal's digestive tract and are deposited
at a distant location.
This allows angiosperms
to spread and populate various regions.
Woody and Herbaceous
Plants
Angiosperms can be
woody or herbaceous. Woody plants contain secondary tissue (bark) that
surrounds the stem. They can live for several years. Examples of woody plants
include trees and some shrubs. Herbaceous plants lack woody stems and are
classified as annuals, biennials, and perennials. Annuals live for one year or
season, biennials live for two years, and perennials come back year after year
for many years. Examples of herbaceous plants include beans, carrots and corn.
Angiosperm Life Cycle
Angiosperms grow and
reproduce by a process called alternation of generations. They cycle between an
asexual phase and a sexual phase. The asexual phase is called the sporophyte
generation as it involves the production of spores. The sexual phase involves
the production of gametes and is called the gametophyte generation. Male and
female gametes develop within the plant flower. The male microspores are contained
within pollen and develop into sperm. Female megaspores develop into egg cells
in the plant ovary. Angiosperms rely on the wind, animals, and insects for
pollination. Fertilized eggs develop into seeds and the surrounding plant ovary
becomes the fruit.
Fruit development
distinguishes angiosperms from other flowering plants called gymnosperms.
Monocots and Dicots
Angiosperms can be
divided into two main classes depending on seed type. Angiosperms with seeds
that possess two seed leaves after germination are called dicots
(dicotyledons). Those with a single seed leaf are called monocots
(monocotyledons). These plants also differ in the structure of their roots,
stems, leaves, and flowers.
Monocots and Dicots
| Roots | Stems | Leaves | Flowers | |
|---|---|---|---|---|
| Monocots | Fibrous (branching) | Complex arrangement of vascular tissue | Parallel veins | Multiples of 3 |
| Dicots | Taproot (single, primary root) | Ring arrangement of vascular tissue | Branching veins | Multiples of 4 or 5 |
Examples of monocots include grasses, grains, orchids, lilies, and palms. Dicots include trees, shrubs, vines, and most fruit and vegetable plants.
source
https://www.thoughtco.com/angiosperms-373297
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