2-D says, “We Monarchs like plants, especially milkweed! We lay our eggs on milkweed because, when our caterpillars hatch, that’s all they’ll eat. If you want to see us in your yard, grow milkweed. As adult butterflies, we like to sip nectar from all sorts of brightly-colored flowers, as long as they’re the sorts of flowers that provide us a place to land and walk around as we probe down into the flowers with our tongues.”

Monocots and Dicots

monocot and dicot
Monocots and Dicots
Division/Phylum Angiospermae is sometimes called Division Anthophyta (anthe = flower; phyto = plant) because the common name for this group is the “flowering plants.” Angiosperms are so named because the seeds are enclosed within a fruit of some sort.

Division Angiospermae contains two main classes: Class Monocotyledones (the “monocots”) and Class Dicotyledones (the “dicots”). These two classes can be distinguished in a number of ways, including:

Class Seeds Leaves Flowers Roots Stem Vascular Tissue
Monocots one nutrient storage area (cotyledon) parallel veins
Monocot Leaves
flower parts in 3
Monocot Flowers
many fibrous roots bundles scattered throughout the stem
Dicots two nutrient storage areas (cotyledons) net or branching veins
Dicot Leaves
flower parts in 2, 4, or 5
Dicot Flowers
one main taproot (may have smaller roots branching off) bundles arranged in a ring

Angiosperm Anatomy:

The parts of an Angiosperm include:

Botanists group species of plants (or, from the other direction, the monocots and dicots can be subdivided) based on a number of characteristics. Botanists pay particular attention to how the flowers are put together:

Complete Flower A complete flower has all four layers of parts.
Incomplete Flower (petals missing) An incomplete flower lacks one or more layers. These knotweed flowers lack petals (corolla).
Perfect Flower A perfect flower had both “sexes” — both stamens and pistil(s). A monoecious plant has perfect flowers or has both male and female flowers on the same plant (for example, Easter lily, pea, dandelion, and rose).
Imperfect Flowers (male and female) An imperfect flower is lacking either the pistil or stamens. A dioecious plant has imperfect flowers on separate male and female plants (for example, marijuana, hops, persimmon, and boxelder). Note that plants such as ginkgo, a gymnosperm which doesn’t produce flowers but which has separate male and female reproductive structures on separate male and female plants, are also referred to as being dioecious.
Regular Flower A regular flower is radially symmetrical.
Irregular Flower An irregular flower has bilateral symmetry, and is also known as a zygomorphic flower.

Multiple flowers can be arranged or clustered in various ways, as shown in this graphic.

Flower Arrangements

Angiosperm Life Cycle:

Life Cycle Diagram

Angiosperms have alternation of generations with the 2n sporophyte being the dominant generation. The anthers, which are the equivalent of microsporangia, produce microspores by meiosis, and the microspores develop into male gametophytes (= pollen).

The ovaries, which are the equivalent of megasporangia, produce megaspores which grow into female gametophytes, each of which then produces an egg.

Note that technically the “sex organs” of a plant aren’t because they produce spores (micro- or mega-) which turn into male or female gametophytes. The gametophytes bear the true sex organs, such as they are, and are where eggs or sperm are actually produced.

By some means (wind or an animal pollinator), the pollen is transferred to the stigma of the pistil, and a pollen tube grows down into the ovary. Eventually, two sperm nuclei travel down the pollen tube. Pollination is the transfer of the male gametophyte (pollen) to the stigma of the female, while fertilization is when the sperm nucleus and egg nucleus unite.

Angiosperms have an unusual thing called double fertilization. When the sperm nuclei reach the female gametophyte, one sperm nucleus and the egg cell unite to form a new 2n zygote (which grows into an embryo). The other sperm nucleus and two nuclei from the female gametophyte join to form 3n endosperm which often serves as food for the embryo.

The embryo sporophyte consists of:

Other, Related Information:

Photographs of various angiosperms
Wildflower indentification practice “game”
Further technical information on plant families.

Copyright © 1997 by J. Stein Carter. All rights reserved.
This page has been accessed Counter times since 16 Mar 2001.