By: Skyler Brennan, Jasmine Patel, and Whitney Sweat
Angiosperms are seed-producing land plants having the largest number of identified species in the plant kingdom. They are often referred to as flowering or fruit-producing plants, and are the predominant primary producers of most ecosystems. These flowering plants are distinguishable from other plants in that they not only flower, but also have their seeds completely enclosed in the ovary which forms a fruiting body to protect the seeds. These seeds are also distinct in that they have an endosperm that provide them with nutrients.
Monocots vs. Dicots
Angiosperms are divided into two categories: monocots and dicots. There are many factors that distinguish the two groups, but the primary distinction is the number of cotyledons. Cotyledons are the first leaves produced by the embryo of a seed-bearing plant; monocots contain one cotyledon, and dicots contain two. However, other distinctions are easier to observe, such as flower petals and leaf venation. Monocots usually have three of six petals, with parallel venation. Dicots usually have four or five petals, with netted venation.
Parts of a flower
The main flower parts are the male part called the stamen, and the female part called the pistil. The stamen has two parts anthers, which produce pollen, and filament, which is a thin stalk that supports the anther. The pistil consists of the stigma, style, and ovary. The stigma is the sticky surface at the top of the pistil where pollen germinates. The style is the structure that holds up the stigma. The ovary contains the ovules, which carry female gametes, and is the location where the ovules are produced. Other parts of the flower include petals, sepals, and receptacles. Petals are parts of the flower that are often colored and usually are the parts that attract pollinators. The sepals are the outer parts of the flower (often green and leaf-like) that protect the flower before it opens. Receptacles are part of the flower stalk that hold the floral organs.
An angiosperm’s life cycle characterized by switching between a diploid sporophyte generation and a haploid gametophyte generation. The sporophyte generation produces flowers and spores, while the haploid gametophyte generation produces gametes. A unique hallmark of the angiosperm life cycle is double fertilization, where two sperm fertilize two cells. One of the fertilized cells is the zygote, and the other is the endosperm that provides nutrients to the zygote.
More on the life cycle of a flowering plant can be found from this animation: Angiosperm Life Cycle
Angiosperms use their flowers to reproduce where the pollen from the anther is transferred to the stigma in a process known as pollination. Once reaching the stigma, the pollen is transferred down the style into the ovary where fertilization occurs to produce a seed or fruit (the embryo).
More information can be found from this short video: Reproduction of Flowering Plants
Common Model Organisms
A model organism is a non-human species used to understand biological phenomena. The findings from these organisms provide intuition on how other organisms work.