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| ## purpletop {#purpletop .Title-Header}                               |
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| *Tridens flavus* (L.) Hitchc.                                         |
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| Plant Symbol = TRFL2                                                  |
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Contributed by: USDA NRCS Plant Materials Program

##### Alternate Names {#alternate-names .Header-3}

greasegrass

##### Uses {#uses .Header-3}

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.

##### Status {#status .Header-3}

Please consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status (e.g. threatened or endangered
species, state noxious status, and wetland indicator values).

##### Description {#description .Header-3}

*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.

##### Adaptation and Distribution {#adaptation-and-distribution .Header-3}

![Color image of Purpletop (Tridens
flavus)](media/image2.jpeg){width="3.1251968503937007in"
height="1.9271653543307086in"}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.

For a current distribution map, please consult the Plant Profile page
for this species on the PLANTS Website.

##### Establishment {#establishment .Header-3}

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.

##### Management {#management .Header-3}

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 {#pests-and-potential-problems .Header-3}

This section is under development.

##### Cultivars, Improved, and Selected Materials (and area of origin) {#cultivars-improved-and-selected-materials-and-area-of-origin .Header-3}

No improved cultivars have been released.

##### Prepared By & Species Coordinator:  {#prepared-by-species-coordinator .Header-3}

USDA NRCS Plant Materials Program

##### 

##### Edited: 05Feb2002 JLK 060818 jsp {#edited-05feb2002-jlk-060818-jsp .Header-4}

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

*The U.S. Department of Agriculture (USDA) prohibits discrimination in
all its programs and activities on the basis of race, color, national
origin, sex, religion, age, disability, political beliefs, sexual
orientation, and marital or family status. (Not all prohibited bases
apply to all programs.) Persons with disabilities who require
alternative means for communication of program information (Braille,
large print, audiotape, etc.) should contact USDA\'s [TARGET
Center](http://www.usda.gov/oo/target.htm) at 202-720-2600 (voice and
TDD).*

*To file a complaint of discrimination write USDA, Director, Office of
Civil Rights, Room 326-W, Whitten Building, 14th and Independence
Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964 (voice or
TDD). USDA is an equal opportunity provider and employer.*

*Read about [Civil Rights at the Natural Resources Convervation
Service](http://www.nrcs.usda.gov/about/civilrights/).*