Biological Name:

Tridens flavus (Purpletop)

Natural Habitat:

Purpletop: This plant is native to North America and grows in a variety of habitats, including fields, meadows, and along roadsides.


Purpletop is a perennial weed that is native to the Americas. It has hairy stems and leaves and the leaves are oval-shaped with toothed edges. The

Frequently Asked Questions (FAQs)

Q: What does purple top grass look like?
A: Tall redtop or Purple-top is a 2 1/2-7 ft. tall perennial grass with drooping branches bearing widely spaced reddish-purple spikelets. In mass, this species puts a purple top on old fields and open woods. The plant becomes brown in fall.

Q: Do you cut back purple grass?
A: Pruning and Maintenance If, in your neck of the woods, this plant is ever-purple, cut it back in late winter or early spring to encourage lots of fresh, attractive growth. Wear gloves and long sleeves, as the leaves can be quite sharp. Learn more about pruning ornamental grasses.

Q: When should I plant purple grass?
A: Like most ornamental grasses, purple fountain grass can be planted nearly any time of year, though it establishes best in spring.

Q: Is purple grass invasive?
A: However, according to Missouri Botanical Garden, “’Rubrum’, sometimes commonly called purple or red fountain grass, is a burgundy-red leaved cultivar that is not invasive under any circumstances because, unlike the species, it rarely sets seed.” However, be careful if you grow several cultivars together because with …

Q: What do you do with purple grass in the winter?
A: Red or purple fountain grass (Pennisetum setaceum ‘Rubrum’) is hardy in zones 8 to 11 so it will not survive Wisconsin winters. Some gardeners have had success digging and potting up the plants to overwinter indoors. Keep the plants in a cool, not freezing, dark location with slightly moist soil.

Q: Do purple grasses come back every year?
A: But will Purple Fountain Grass return every year? Purple Fountain Grass is a tender perennial plant that will die back during the winter but can return and grow back during the spring.

Q: Why is my purple grass turning brown?
A: Overwatering – allow time for the soil to dry between waterings. Too much fertilizer – instead of using chemicals, a fertilizer like Azomite that has trace minerals and vitamins, along with seaweed and kelp can help. Plants that are in pots – if the grass is root-bound, it can’t absorb water from the soil easily.

Q: How do I identify a purple top?
A: Purpletop tridens can be identified by its ligule of stiff hairs on both sides of the leaf sheath at the collar (Phillips Petroleum, 1956). The pyramid shaped inflorescence is open, drooping, 6 to 14 inches or more long with spreading lower branches 4 to 10 inches long (Gould, 2008; Hatch and Pluhar, 1995) (Fig. 2).

Q: What do you wear under a purple top?
A: Blue. Blue is one of the colors you can pair with purple. Blue denim fabrics, blue tops, and scarves can be a nice touch to your outfit depending on the shade. When wearing a darker shade of purple, you can pair it with a light and faded shade of blue.

Q: Why are purple clothes rare?
A: Dye makers harvested mucus from the shell and heated it in an alkaline solution. The dipped yarn in this solution and exposed it to sunlight, turning it purple. About 250,000 snails were required to make an ounce of purple dye. Tyrian purple was rare and expensive, making purple clothing costly.

Q: Is EDTA purple top?
A: EDTA whole blood = Lavender (purple) top tube Label this tube with owner name, animal ID, and as EDTA whole blood. This tube (plus 2 blood smears) should be submitted for a hemogram without separation or freezing but should be kept cool.

Q: How can you tell if a purple gem is real?
A: Authentic Amethyst gems should have some imperfections and different shades of purple. An Amethyst gem that is one solid color is most likely fake. Real Amethyst stones will have color zoning including shades of white and blue along with purple.

Q: Why is luxury purple?
A: Purple’s elite status stems from the rarity and cost of the dye originally used to produce it. Purple fabric used to be so outrageously expensive that only rulers could afford it. The dye initially used to make purple came from the Phoenician trading city of Tyre, which is now in modern-day Lebanon.

About the author

Samuel is a gardening professional and enthusiast who has spent over 20 years advising homeowners and farm owners on weed identification, prevention and removal. He has an undergraduate degree in plant and soil science from Michigan State University.