Calling all green thumbs!
Join us on a journey to cover key plant terminology from A-Z, and learn why these terms are important for understanding invasive species.
Today, we will cover S-U.
Seed bank
Seed bank: definition
The collection of dormant but viable seeds present in the soil or leaf litter, built up over time from seeds dropped by plants in the area. Seed banks can persist for years or even decades, with seeds germinating when environmental conditions (light, moisture, temperature) become favourable.
How this term applies to invasives
Invasive plants often produce abundant, long-lived seeds that accumulate in the seed bank. This hidden reserve means even after visible plants are removed, new seedlings can emerge for many years, making complete eradication a long-term challenge.
For example, Scotch broom (Cytisus scoparius) produces large numbers of hard-coated seeds that can remain viable in the soil for decades. Even after removal, seeds in the soil continue to germinate for years, creating a persistent reinvasion problem.
Scotch broom
Scotch broom
Suckers
Suckers: definition
Vegetative shoots that arise from the base of a plant’s stem or from its roots, often at some distance from the main trunk. These shoots are genetically identical to the parent and bypass seed germination, allowing for rapid clonal expansion.
How this term applies to invasives
Many woody invasives, such as tree of heaven (Ailanthus altissima), use suckering to spread laterally and form dense thickets. Even if the main plant is cut down, the root system can continue sending up suckers, making control efforts labor-intensive.
Tree of Heaven. Photo credit: E. Galloway
Tree of Heaven. Photo credit: R. Gardner, Bugwood.org.
Taproot
Taproot: definition
A deep, central primary root that grows vertically downward, with smaller lateral roots branching off. Taproots serve as storage organs, containing reserves of carbohydrates and water, allowing plants to survive adverse conditions.
How this term applies to invasives
Taproot-bearing invasives like common burdock (Arctium minus) are difficult to remove because any remaining portion of the root can regenerate shoots. Their stored energy enables them to regrow vigorously after attempts to cut or pull them.
Common burdock
Tuber
Tuber: definition
A swollen, underground stem or rhizome segment that stores nutrients and starches for the plant. Tubers have “eyes” or buds that can sprout new shoots and roots, enabling the plant to reproduce asexually.
How this term applies to invasives
Tubers in plants like yellow nutsedge (Cyperus esculentus) allow invasives to spread underground. Even small fragments left behind during removal can regrow into full plants, making mechanical control extremely challenging.
Yellow nutsedge. Photo credit: C. Bryson, USDA Agricultural Research Service, Bugwood.org
Yellow nutsedge. Photo credit: H. Schwartz, Colorado State University, Bugwood.org
Umbel
Umbel: definition
A type of inflorescence in which all the flower stalks (pedicels) radiate from a single point at the top of the stem, resembling the ribs of an umbrella. Umbels can be simple (single layer) or compound (multiple layers), and often produce many flowers closely packed together.
How this term applies to invasives
Umbel-forming invasives, such as giant hogweed (Heracleum mantegazzianum), can produce massive numbers of seeds in a single season. Their open flower structure attracts a wide range of pollinators, aiding cross-pollination and increasing seed viability, which accelerates their spread.
Giant hogweed
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