Flowering Plant Anatomy 101

Flowering Plant Anatomy 101
Flowering Plant Anatomy 101

For anyone who has not had formal training in biology, botany, or horticulture, deciphering the jargon used to describe plant characteristics can be a nightmare! We commonly read terms like monoculture, dicot, and anthers when reading about invasive species, but what does this all mean?

Have no fear, we have put together a beginner’s guide to plant anatomy and the terms used when describing and identifying invasive species.

THE FLOWER: the reproductive organ, where seeds are produced.

Angiosperm is the word used to describe flowering plants that reproduce sexually through their flowers. Some have male and female reproductive organs on separate flowers, whereas others have both male and female parts on the same flower.

The male reproductive organ of the flower is the stamen. At the end of the stamen is the anther, which produces the pollen.

The female reproductive organ of the flower is the carpel. The carpel is composed of the stigma, where the pollen sticks, and the ovary. The ovary contains ovules that will eventually develop into fruit and later seeds.

The petals of a flower play an important role in reproduction as they attract pollinators to the plant’s reproductive organs. These showy petals come in all colours and sizes.

Photo credit: Edublogs
THE LEAF: a primary organ of the plant that captures sunlight for photosynthesis.

Several characteristics are used when describing the leaves of a plant, including venation, arrangement, and arrangement on the stem.

Venation is the arrangement of veins in a leaf: just like humans, plants have vasculature to transport water and nutrients. There are 3 types of venation in angiosperm leaves:


Invasive example: Yellow Flag Iris

Pinnate (feather-like)

Invasive example: Small Periwinkle

Large Periwinkle stem and leaves (James H. Miller, USDA Forest Service, Bugwood.org)

Large Periwinkle stem and leaves (James H. Miller, USDA Forest Service, Bugwood.org)

Palmate (branching)

Invasive example: English Ivy

Arrangement of the leaf refers to the one or many leaf blades attached to the stem via the petiole (stalk). The leaves can either be simple or compound.

An example of an invasive plant that has simple leaves is Garlic Mustard.


Compound leaves have 2 or more subunits called leaflets, an example of this leaf type is seen on the invasive Himalayan Blackberry.


The arrangement of leaves along the stem of a plant is an important feature to look out for when identifying plants. There are 3 possible arrangements:


Ex. Knotweed 

Japanese Knotweed


Ex. Wild Clematis

Wild Clematis flowers

Photo credit: John Brears


Ex. Eurasian Watermilfoil 

Graves Lovell, Alabama Department of Conservation and Natural Resources, Bugwood.org

THE STEM: supports the growing plant body and carries water and nutrients between the roots and leaves.

The node is where a leaf attaches to the stem. The area of stem between successive nodes is called the internode.

At a node, there is an auxiliary bud, which can develop into a leafy shoot (branch).

At the top of the stem is the terminal/apical bud, which is the primary area of growth for the stem.

Photo credit: Leaving Certificate Biology
THE ROOTS: anchor the plant and absorb water and minerals from the soil.

The most common root system for angiosperms is one with a primary taproot. As the taproot grows vertically down, it sends off smaller lateral roots that grow horizontally. An invasive with a taproot system is Common Burdock.

Common Burdock Taproot

Some angiosperms have a fibrous root system that is shallow in the soil and branching in many directions. An example of an invasive with a fibrous root system would be Himalayan Balsam.

Invasive Reproduction
Photo credit: M. Kothmann

Many pesky invasives thrive due to their immense root network underground. A key feature of invasive species is their ability to rapidly spread, which relies on efficient methods of reproduction. Seed and flower production are energetically taxing on a plant and often slow down vegetative growth.

To save on energy, some plants send out runners (or stolons), which are stem-like projections, extending out from the parent plant. The runners grow along the surface of the soil until they find a spot to grow into a daughter plant. Yellow Lamium is an example of an invasive that spreads in this way.

A similar method of plant reproduction is through a rhizome. This is a continuously growing underground stem, extending horizontally, which contains nodes where the lateral shoots and roots of daughter plants grow from. Common Tansy is an example of an invasive that spreads both through seed and by a creeping rhizome.

OTHER TERMS: used to describe angiosperms and their lifecycle
Monocots vs Dicots
  • Annual: have a lifespan of one year, for example, Bachelor’s Button.
  • Perennial: grow back every spring, persisting for several years, often with new herbaceous growth, for example, Common Tansy.
  • Biennial: takes 2 years of growth from seed to complete their lifecycle, for example, Common Foxglove.

A large area with only one plant species growing in it. This term is commonly used to describe the growing pattern of invasives as many form monocultures that smother and outcompete the native plants in that area.

Orange Hawkweed monoculture

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