Flat Pea (Sylvestris)

The Flat Pea (Sylvestris) is generally described as a perennial vine or forb/herb. This is not native to the U.S. (United States) . Leaves are not retained year to year.

Uses of : Landscaping, Medicinal, Culinary, etc.

Flatpea is a long-lived erosion control plant that can grow on severely disturbed soil under acid conditions and begin a soil improvement process. It requires little input once established. Flatpea will inhibit the ability of other plants to invade the stand after it acheives full cover, and can be used to control woody plant encroachment of utility rights-of-way. Flatpea has also received extensive interest as a forage due to the high protein content, however the presence of high concentrations of diaminobutyric acid (DABA) has rendered this use unlikely. DABA is toxic to non-ruminent livestock, and also to ruminants if fed in quantity before the rumen is acclimated to it. Birds will utilize the seed and are not affected by DABA.

General Characteristics

Flatpea climbs through the use of tendrils and can attain heights of 5-7 feet if support is available. When no support is nearby, the plant has a height of 18-30 inches. In either case, a well-established stand forms a dense mat of vegetation. The stems and petioles are winged with leaf-like appendages. The leaf consists of two long, narrow leaflets with parallel veins and bears the tendril from juncture of the leaflets. The flowers are deep pink, and produce 2-inch long seed pods that contain the hard round seed. Both the seed and the pod are black or dark gray at maturity. Flatpea closely resembles sweetpea and perennial pea.

Required Growing Conditions

Flatpea is adapted throughout the Northeast to soils that are moderately well drained or drier. It may also grow well on some sloping soils that are somewhat poorly drained. It is drought tolerant once established, and will grow on soils with a fines content as low as 15 percent (passing a 200 mesh seive). Low fertility and acid soils can successfully grow flatpea, and it will tolerate moderate shade better than will crownvetch.

Flatpea is distributed primarily in the northwest and scattered throughout the eastern United States.

Cultivation and Care

Flatpea will not establish successfully unless the seed is incorporated into the soil. Broadcast and hydroseeding will not work unless subsequent erosion covers the seed, or a heavy mulch is applied. The best way to incorporate flatpea seed on disturbed sites is to track it in with a bulldozer. Inoculated flatpea seed must be spring planted, or dormant planted in mid-fall. A drill can also used to plant the seed 1-1 1/2 inches deep. Flatpea is always planted with a grass companion (typically tall fescue) to provide quick cover during the 2-3 year establishment period. With good agronomics on a good site, flatpea will cover the soil in 2 years. With poor methodology it may never be successful.Lime is needed if the soil is below a pH of 5.0, and moderate levels of phosphorus and potash are beneficial. Coat the seed with the specific inoculant immediately prior to planting. Plant flatpea at 20 pounds per acre with 15 pounds of tall fescue. More seed will not make up for lack of incorporation as outlined above.

General Upkeep and Control

None is required. Mow the stand no more than once per year, after full bloom, and no sooner than the third year after planting.

Cultivars, Improved, and Selected Materials (and area of origin) ‘Lathco’ (western WA) is the only cultivar, and is available in the seed trade.

Control Please contact your local agricultural extension specialist or county weed specialist to learn what works best in your area and how to use it safely. Always read label and safety instructions for each control method. Trade names and control measures appear in this document only to provide specific information. USDA, NRCS does not guarantee or warranty the products and control methods named, and other products may be equally effective.

Plant Basics
General Type Vine, Forb/herb
Growth Duration Perennial
Plant Nativity Introduced to U.S.
Physical Characteristics
Displays Fall Colors No
Flower Conspicuousness No
Gardening Characteristics
Cold Stratification Required No
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 0–0 pH
Precipitation Range 0–0 inches/yr
Planting Density 0–0 indiv./acre
Minimum Frost-Free Days 0 day(s)
Sustainability & Use
Leaf Retention No
Fire Resistant No

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