Purpletop Tridens (Flavus)

The Purpletop Tridens (Flavus) is generally described as a perennial graminoid. This is native to the U.S. (United States) has its most active growth period in the summer . The greatest bloom is usually observed in the late summer, with fruit and seed production starting in the summer and continuing until fall. Leaves are not retained year to year. The Purpletop Tridens (Flavus) has a short life span relative to most other plant species and a moderate growth rate. At maturity, the typical Purpletop Tridens (Flavus) will reach up to 2.5 feet high, with a maximum height at 20 years of 0 inches.

The Purpletop Tridens (Flavus) is usually not commercially available except under contract. It can be propagated by seed. It has a rapid ability to spread through seed production and the seedlings have high vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -23°F. has high tolerance to drought and restricted water conditions.

Uses of : Landscaping, Medicinal, Culinary, etc.

Purpletop is a perennial, warm season grass that is consumed by all grazing livestock. It is well adapted to shallow, droughty, infertile soil and provides forage in the summer and on sites where cool season forages do not produce well. It can be planted alone or in mixes with other warm season grasses.

General Characteristics

Tridens flavus (L.) Hitchc., purpletop, is a bunchgrass with erect tufted culms. It is 35 to 75 inches tall. Leaf blades are flat, often less than 1/2 inch wide and 10 to 27 inches long, lax, smooth, and glossy green. The leaf sheath is flattened near the base, keeled (has a central rib), and overlapping. The ligule (projection up from inside leaf sheath where sheath meets blade) is a ring of short hairs. The seedhead is an open cluster, 8 to 14 inches long, spreading, pyramid shaped, usually purple, sometimes nearly black. The seedheads droop and are covered with an oily or grease-like substance. There are 465,000 seeds per pound.

Required Growing Conditions

Purpletop is adapted to areas of the eastern United States with more than 30 inches of rainfall, from Maine to eastern Nebraska to eastern Texas to Florida. It is not common in northern New England or New York, especially on inland sites, where poor winter hardiness is a problem.

Purpletop is adapted to soils that are well-drained to droughty, shallow and rocky, fertile to sterile. It is tolerant of road salt and often colonizes roadside sites, especially in Pennsylvania and south.

Cultivation and Care

Purpletop should be seeded in spring, when soil moisture and temperatures are conducive to germination. Seeding depth should be 1/4 inch. Ten to fifteen pounds PLS (pure live seed) per acre is sufficient for drill seedings. For broadcast seedings, the seeding rate should be 20 to 25 pounds PLS per acre.Purpletop seedlings are slow to develop and competition from weeds and/or cool season grass may overwhelm the stand on the better soils. Stands should be established using a no till drill to minimize the number of weed seeds exposed. The cool season grasses must be thoroughly killed with contact herbicide before seeding. Purpletop is tolerant of most broadleaf herbicides. (Read labels for application amounts and grazing restrictions.)The most common cause of purpletop establishment failures is a loose seedbed. Conventionally tilled plantings should be packed before and especially after the seeding. The seedbed should be firm, showing only a slight imprint when stepped on. When using a no till drill, be sure the furrows are closed to avoid seed exposure and drying. This is effectively done by cultipacking after drilling.

General Upkeep and Control

Fertilization to maintain moderate levels of phosphorus and potassium are recommended for establishment. Nitrogen fertilization is not recommended until the purpletop is established and above the competition. It may be applied late in the first summer at 20 to 40 pounds per acre or early in the second summer at 40 to 80 pounds per acre. Fertilizer should be applied in subsequent years to maintain vigor and enhance production. Mature stands resist weed and brush encroachment, but are tolerant of mowing or burning for control. Cool season grasses and legumes can be controlled with a contact herbicide or overgrazing before the purpletop emerges. Rotational grazing of purpletop that removes half the above ground growth (6 to 12 inches down to 3 to 6 inches) will provide the best forage and maintain the stand. With care, a stand will last indefinitely.

Pests and Potential Problems This section is under development.

Cultivars, Improved, and Selected Materials (and area of origin) No improved cultivars have been released.

Plant Basics
Growth Rate Moderate
General Type Graminoid
Growth Period Summer
Growth Duration Perennial
Lifespan Short
Plant Nativity Native to U.S.
Commercial Availability Contracting Only
Physical Characteristics
Bloom Period Late Summer
Displays Fall Colors Yes
Shape/Growth Form Bunch
Drought Tolerance High
Shade Tolerance Intolerant
Height When Mature 2.5
Vegetative Spread None
Flower Color Yellow
Flower Conspicuousness No
Fruit/Seed Abundance Medium
Fruit/Seed Seasonality Summer Fall
Seed Spread Rate Rapid
Gardening Characteristics
Propagations (Ways to Grow) Seed
Moisture Requirements Low
Cold Stratification Required No
Minimum Temperature -23
Soil Depth for Roots 10
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Regrowth Rate Rapid
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 4.5–6.5 pH
Precipitation Range 17–17 inches/yr
Planting Density 0–0 indiv./acre
Soil Textures Coarse, Fine, Medium
Soil Depth for Roots 10
Minimum Frost-Free Days 150 day(s)
Salinity Tolerance None
CaCO3 Tolerance Low
Sustainability & Use
Leaf Retention No
Palatability High
Fire Resistant No
Causes Livestock Bloating None

Source: USDA, NRCS, PLANTS Database, plants.usda.gov.
National Plant Data Center, Baton Rouge, LA 70874-4490 USA