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// SPECIES PROFILE · CROP · HEIRLOOM · NITROGEN FIXER

Cowpea / Black-Eyed Pea

Vigna unguiculata

The cowpea is the warm-season legume that built the kitchen gardens of the American South and the smallholder farms of the southern Great Plains. A West-African domesticate carried to the Carolinas in the 1600s and into Indian Territory by both enslaved farmers and Indigenous growers, it thrives on exactly the conditions that flatten ordinary garden peas: long July afternoons, hard red Cross Timbers clay, three weeks without rain, and soil temperatures north of 80°F. It fixes its own nitrogen, smothers weeds, feeds bumblebees and skipper butterflies through August, and yields beans, fresh shellies, snap pods, edible greens, and a generous green-manure crop — one of the highest returns on effort of any plant you can grow in NE Oklahoma.

// QUICK FACTS
Family
Fabaceae (legume family)
Group
Crop — warm-season annual legume
Native range
West & Central Africa; domesticated >3,000 yrs ago
USDA hardiness
Annual; needs frost-free 60–90 day window (Tulsa = 7a/7b)
Mature size
Bush types 1–2 ft · vining types 3–6 ft
Sun
Full sun (8+ hrs)
Soil
Sandy loam ideal; tolerates poor sand and red clay
Water
Drought-tolerant; needs water at flowering & pod-fill
Soil temperature for sowing
Min 65°F · ideal 75–85°F
Days to first bloom
45–60 from sowing
Days to dry seed
80–100 from sowing
Nitrogen fixation
Yes — Bradyrhizobium sp. (cowpea group)
Pollinators
Bumblebees, leafcutter bees, long-tongued bees
Larval host
Long-tailed skipper (Urbanus proteus); bean leafroller
Wildlife
Doves, quail and turkey eat shattered seed; deer browse foliage
Cowpea / black-eyed pea (Vigna unguiculata) — pods and characteristic dark hilum on dry seed
Vigna unguiculata — the heat-loving Southern pea that has been a staple of NE Oklahoma kitchen gardens since territorial days. Photo via Wikipedia / Wikimedia Commons.

Identification

[ field key — growth habit · trifoliate leaf · flower · pod · seed ]

Habit & growth form

A warm-season annual herb in three loose habit classes: bush (compact, self-supporting, 1–2 ft — e.g. 'California Blackeye No. 5'), semi-vining / prostrate (sprawling runners 2–3 ft — the classic Southern field pea), and climbing / pole (twining vines 4–6+ ft — the yard-long bean subspecies V. unguiculata ssp. sesquipedalis). Roots are taprooted with abundant fine laterals; mature plants have visible pinkish-red nitrogen-fixing nodules on the lateral roots when soil rhizobia are present.

Foliage & stem

Stems are smooth, often slightly purple-tinged at the nodes. Leaves are alternate and trifoliate (three leaflets per leaf) on a long petiole, with two small persistent stipules at the base. Each leaflet is ovate to lanceolate, 2–5 in long, smooth and glossy, with an entire margin and a distinctly asymmetric base on the lateral leaflets — a quick way to separate cowpea from common bean (Phaseolus vulgaris), whose leaflets are more symmetric and matte.

Flowers & pods

Flowers are typical pea flowers (papilionaceous: banner, two wings, keel) held singly or in small clusters on long peduncles that lift them above the foliage. Color ranges from pale lavender to white to deep purple depending on cultivar, opening at sunrise and fading by mid afternoon. Pods follow within 10–14 days: linear, slightly curved, 4–12 in long, green ripening to tan, yellow, or purple. Each pod holds 8–20 seeds.

Seed & lookalikes

Seeds are kidney-shaped to nearly round, 6–10 mm, with a conspicuous elongated dark hilum (the "eye") that is diagnostic for the species. Color varies wildly: black-eyed (white with a black eye), pink-eyed purple-hull, brown crowder, cream, red, speckled. Easily confused with common bean seedlings, but cowpea cotyledons stay below the soil (hypogeal germination) while bean cotyledons push up above (epigeal). Mature cowpea also lacks the climbing tendrils of pole bean: it twines with the stem itself.

Habitat & Range in NE Oklahoma

Cowpea is not native to North America — it was domesticated in the savannas of West and Central Africa, carried across the Atlantic with the slave trade in the 17th century, and naturalized into Southern foodways within a generation. By the time Oklahoma was opened to non-Indigenous settlement in 1889, cowpeas were already being grown by Cherokee, Creek and Choctaw farmers in the eastern half of Indian Territory, both as a food crop and as a livestock forage. They became one of the standard "Southern peas" of the Cross Timbers and the Arkansas River valley because they tolerate exactly the conditions that defeat snap peas and English peas: high heat, low humidity in the air but adequate soil moisture below, and the heavy red clay of NE Oklahoma when worked into a friable seed bed.

Cowpeas do not naturalize as a weed in Oklahoma — they require disturbed, cultivated soil and warm temperatures, and the few volunteers that appear on the edge of a fall garden are killed by the first hard frost. Wild and weedy cowpea populations are not part of the Oklahoma flora. As a cultivated crop, however, they are documented across all 77 counties; OSU Extension and the Noble Research Institute have evaluated cowpea both as a kitchen-garden staple and as a summer cover crop and grazing legume for the southern Great Plains. For the home gardener in the Tulsa, Bartlesville and Tahlequah corridor, cowpeas are the single most reliable legume from late May through first frost (typically the last week of October).

Ecology & Wildlife Value

[ nitrogen fixation · pollinators · lepidoptera · cover · pests ]

Nitrogen fixation & soil

Like all legumes, cowpea forms a symbiosis with soil bacteria — specifically the cowpea group of Bradyrhizobium — that inhabit pinkish nodules on its lateral roots and convert atmospheric N₂ to plant-available ammonium. A healthy cowpea crop in NE Oklahoma fixes roughly 40–100 lb of N per acre over a single warm season; the residue tilled in or left on the surface carries a substantial nitrogen credit forward to the following crop. This is why cowpea is one of the standard summer cover crops on rested vegetable beds in the region.

Pollinators & floral biology

Cowpea flowers are predominantly self-pollinating — the keel encloses the stigma and anthers and pollination usually occurs before the flower opens — but they are also actively visited by bumblebees, leafcutter bees and other long-tongued natives, who can effect 5–15% outcrossing. The flowers are nectar-rich and contribute to NE Oklahoma bumblebee forage during the August dearth, when little prairie forb is in bloom in disturbed habitats.

Lepidoptera & insect food web

Documented larval host of the long-tailed skipper (Urbanus proteus) — a striking iridescent-blue skipper of the southeastern US whose caterpillars fold cowpea leaflets into shelters — and of the bean leafroller and several noctuid moths. Cowpea aphids (Aphis craccivora) feeding on the plant in turn support lacewings, lady beetles, hover flies and parasitoid wasps; the crop functions as an in-garden insectary if you tolerate light aphid colonies.

Wildlife forage

Mourning doves, bobwhite quail and wild turkeys eat shattered seed off the ground; white-tailed deer browse foliage and pull whole plants in fall; raccoons strip standing pods. For dove field plantings on rural NE OK properties, cowpea ('Iron & Clay', 'Red Ripper', 'Combine') is the standard legume component alongside grain sorghum and Egyptian wheat.

Inoculate at planting: If you have not grown cowpea, southern pea or yardlong bean in a bed before, dust the seed with cowpea-group Bradyrhizobium inoculant (sold under names like "EZ-Nitro Pea/Bean Inoculant" with the cowpea group strain) before sowing. The inoculant is cheap, lasts a season in the bag, and roughly doubles N-fixation in soils where the bacterium is absent. Nodules should be visible and pink/red inside within 4–6 weeks of germination.
Aphids & cowpea aphid-borne mosaic virus: Heavy late-summer colonies of black Aphis craccivora can stunt plants and transmit cowpea aphid-borne mosaic virus (CABMV) and bean common mosaic virus. Tolerate light colonies (the predator complex usually catches up); knock heavy colonies down with a water spray or insecticidal soap; remove visibly virused plants and do not save seed from them.

Horticulture & Care

[ sowing · spacing · inoculant · harvest · varieties ]

When to plant

Wait. Cowpea is not a cool-season pea — sown into cold wet ground it rots in place. In the Tulsa region the right window opens around May 1–15 (after soil temperature at 2 in is steady above 65°F) and stays open through mid-July for a standard 60–90 day cultivar. A second sowing in early July gives a fresh-shellie crop in late September. For cover-crop use, sow any time from late May through early August on bare beds.

Planting & establishment

Harvest

Pruning & in-season care

No pruning required. For pole types, pinch the growing tip when the vine reaches the top of the trellis to push energy into pods. Hand-weed early; once the canopy closes cowpea outcompetes most weeds.

Pests & diseases in NE Oklahoma

Notable varieties for NE Oklahoma

Variety Type / habit Distinguishing feature Notes for Tulsa
'California Blackeye No. 5' Bush, blackeye White seed with black eye, smooth and dependable The supermarket black-eyed pea; reliable, early, easy to harvest by hand — the default kitchen-garden pick.
'Pinkeye Purple Hull' Semi-vining, pinkeye Pink-eye seed in deep purple pods that hold above the foliage Classic Southern shellie; pods are easy to spot for picking. Heavy producer in red-clay gardens.
'Mississippi Silver' Bush, crowder Silver-tan crowder seed crammed end-to-end in the pod 1980 AAS winner; nematode-tolerant; a classic for July planting in worked clay loam.
'Whippoorwill' Vining, brown speckled Mottled brown crowder; one of the oldest US heirlooms Documented in Oklahoma since territorial days; vigorous enough to smother weeds. Good for three-sisters.
'Iron & Clay' Vining, mixed Vigorous biomass; mixed seed colors Standard cover-crop / dove-field cowpea across the southern Plains; not the best eating but unbeatable for green manure.
'Red Ripper' Vining, red crowder Deep red seed; very vigorous, drought-hardy Dual-purpose seed/cover; popular with Oklahoma forage producers.
'Yard-long Bean' (ssp. sesquipedalis) Pole, snap 18–36 in green pods eaten fresh Asian-market staple; a cattle-panel trellis pole crop that thrives in July heat when standard green beans quit. Best fresh-eating form.

Cultural & Material Uses

Cowpea is one of the half-dozen plants on which Southern foodways — and a substantial fraction of the West African diaspora's foodways — were built. In NE Oklahoma it sits at the intersection of African American, Indigenous and settler traditions, all of which independently centered the same crop for the same reasons: it works.

Sources & Further Reading

  • USDA NRCS PLANTS Database — Vigna unguiculata: plants.usda.gov/plant-profile/VIUN
  • USDA NRCS Plant Guide — Cowpea (Vigna unguiculata): cover-crop and forage summary for the southern US.
  • Oklahoma State University Extension — Southern Pea Production (HLA-6028) and the OSU Vegetable Garden Planting Guide for cowpea sowing dates and variety recommendations in Oklahoma.
  • Noble Research Institute (Ardmore, OK) — cowpea in summer cover-crop and warm-season grazing systems for the southern Great Plains.
  • USDA SARE — Managing Cover Crops Profitably, 3rd ed., cowpea chapter (nitrogen credit, biomass, termination).
  • Lady Bird Johnson Wildflower Center — Vigna unguiculata plant database entry.
  • Wikipedia — Cowpea: en.wikipedia.org/wiki/Cowpea (CC BY-SA 4.0; portions of the domestication and culinary sections summarize Wikipedia content).
  • Singh, B.B. (2014), Cowpea: The Food Legume of the 21st Century, Crop Science Society of America.
  • Fery, R.L. (2002), "New opportunities in Vigna", in Trends in New Crops and New Uses, ASHS Press.

Photos courtesy of Wikimedia Commons contributors under their respective licenses.

Companion Planting

[ guild · polyculture · cross-layer pairings ]

In a kitchen-garden polyculture, cowpea / black-eyed pea pairs naturally with: comfrey (Symphytum officinale), big bluestem (Andropogon gerardii), basil (Ocimum basilicum), common sunflower (Helianthus annuus), eastern gamagrass (Tripsacum dactyloides), and chile pepper (Capsicum annuum).

In a polyculture bed, cowpea / black-eyed pea pairs with the partners above for pest deterrence, pollination, and soil-building.