Angiosperm

6/13/2016

Angiosperms are plants that produce flowers.

The word angiosperm comes from the Greek words for “vessel” (angeion) and “seed” (sperma). There are 350,000 known species of angiosperm plants and they all generate seeds. Nearly 80% of all the green living plants on earth are angiosperms. This is the most diverse group of plants in the world and they make up the majority of our food supply.

Almond blossoms

Vascular plants

Plants with veins are called vascular plants. Vascular bundles, made up of the xylem and phloem, carry water and nutrients throughout the plant. Angiosperms are vascular plants. The way those veins are arranged within a stem can help you identify a plant. You know those long threads that get caught in your teeth when you eat celery? Those are plant veins.

Monocot v. dicot (FlowerPower207) CC BY-SA 3.0

Until recently, angiosperms were divided into two groups: monocots and dicots. Monocots, such as corn, have a single seed, a single embryonic leaf (cotyledon), fibrous root systems, parallel leaf veins, flower petals in multiples of 3, and scattered veins. Whereas dicots, such as peas, beans, radishes, and nasturtiums, have seeds that split in half, two seed leaves, a taproot, webbed veining, flowers petals in multiples of 4 or 5, and a circular arrangement of veins.

Mature flower diagram (LadyofHats) Public Domain

Genetic testing and electron microscopes have taught us that those generalizations were too simplistic. As a result, dicots have largely been recategorized as a new group, called eudicots. If you want to get super technical, the modern plant classification system identifies 8 different angiosperm groups.

Angiosperm lifecycle

All angiosperms start out as seeds. Seeds are produced when the stigma of a female flower is pollinated by pollen from a male flower’s stamen and the ovules are fertilized. This process is called double fertilization. The seed is protected and fed by fruit that surrounds it. The fruit is actually a mature plant ovary.