Types of Weeds

Most, if not all of the weeds listed on the right get categorized as braodleaf weeds. The dandelion and weeds in lawn links point to some of the most common weeds found on residential lawns.

Technically the term applies to most of the unwanted, leafy, flowering plants that appear in yards and roadsides. It contrasts with grassy weeds, or weeds that produce one leaf at a time, and typically produce no flowers.

Some invasive weeds have a history of being introduced ornamentals, that eventually become a problem in the landscape. Typically they get called invasive weeds because of their propensity to dominate an area leaving little room for native plants.

Garden Weeds in the Age of Jefferson, for example, tells the story of Jefferson's introduction of Fox Glove, Scotch Broom, Chicory and the Perennial Pea, among others, into his Virginia gardens.

Over two hundred years later, they get classified as invasive in many places. Here's a quick peak at them now.

Call it an herb or call it a weed, Chicory (Cichorium intybus) (pictured above, now grows uncontrolled across the United States.

Chicory's current claim to fame finds its roots in the use of the plant's roots as a coffee substitute. Dried, cut and put in a cup of boiling water, the root produces a caffeine free coffee-like beverage.

Young leaves are also edible and have a history of use as a salad ingredient as well as cattle feed.

The plant's blue multi-petal blooms place it squarely in the daisy family (Asteraceae).

Some call it a weed, others call it an ornamental.

Foxglove is easily recognized by the flowers. While they appeal to many gardeners' eyes, the flowers and plants are poisonous when ingested by both humans and animals.

Technically called a flowering vine, perennial pea grows well in most sunny areas in the USDA Hardiness Zone 4 - 7 range.

Two hundred plus years later, the plant has spread across the country, growing aggressively enough in some areas to be considered a noxious weed. In other areas, it grows an an ornamental, turning walls, fences and trellises a shocking pink, red or white color during the summer growing season.

For individuals not inclined to maintain the Everlasting Pea as an ornamental flowering vine, complete removal of the deep tap roots, rhizomes and seeds is recommended. Consistent removal of sprouts over a couple of years should be sufficient to deter continued plant growth.

Depending on the variety, Scotch Broom produces large colorful flowers in shades of red and yellow.

The original proponents of Scotch Broom were less aware of the plant's extra-hardy nature. It grows to heights of nine feet, develops a deep taproot, and is a prolific seed producer.

All these factors combined over time to help spread Scotch Broom over large areas of land, where it became the dominant species, effectively diminishing space for native plant growth.

Growing up to six feet tall, it resembles a thistle on a corn stalk. Multiple small flowers bloom on the plant's spiked flower heads, and today the stems and flower heads are often cut, dried and used in flower arrangements.

Like many weeds, teasel produces a long taproot. Removing the entire root, at any time during the plant's growing cycle, removes the plant.

The cornflower or Batchlor's Button (Centaurea cyanus), a native European species introduced into many a Colonial garden, including Thomas Jefferson's garden at Monticello, subsequently escaped into the natural environment and became established throughout the United States.

The bright blue flowers explain the plant's ornamental popularity. Additionally, it brings with it a medicinal and food source history.

Today, it can be classified as either a weed or an ornamental, depending on its growing location.

© 2008-2012 Patricia A. Michaels