The black eyed pea (Vigna unguiculata), also known as cowpea or southern pea, is a globally cultivated legume crop originating in West Africa. As a member of the Fabaceae family, it has been domesticated for thousands of years and is recognized for its adaptability to warm climates and drought-prone soils. The plant is an important source of protein and is valued for its ability to fix atmospheric nitrogen, which enriches the soil. Its life cycle culminates in the development of the distinctive seed, a process entirely dependent on the reproductive success of its flower.
Structure of the Black Eyed Pea Blossom
The structure of the black eyed pea flower is characteristic of the papilionaceous, or butterfly-like, form common to many legumes. This flower possesses bilateral symmetry, meaning it can only be divided into two mirror-image halves along a single plane. The corolla is composed of five specialized petals that cooperate to protect the reproductive machinery.
The uppermost and largest petal is the banner (or standard), a broad, often colorful petal that serves as a visual attractant. Beneath the banner are two smaller, lateral petals called the wings, which flank the central structure. The final two petals are fused along their edges to form the keel, a boat-shaped structure. This keel completely encloses the flower’s ten stamens and the single pistil, which contains the ovary.
Reproductive Organs
This arrangement shields the male and female reproductive organs. The stamens are typically organized into a diadelphous formation, with nine fused into a sheath and one remaining separate. The stigma, the receptive tip of the pistil, is positioned at the apex of the keel, ready to receive pollen from the anthers clustered around it.
The Timing of Flowering
The initiation of flowering is closely tied to the plant’s overall development and specific environmental cues. Planting occurs once soil temperatures consistently rise above 60 to 65 degrees Fahrenheit, followed by a period of vegetative growth. Flowering generally begins between 40 and 60 days after the seed is sown, depending on the specific cultivar and growing conditions.
Temperature is a primary factor that sustains flowering, as the plant thrives in long, hot summers. While many varieties are considered day-neutral, photoperiod sensitivity influences the transition to reproductive growth in some cultivars. For these plants, a reduction in daylight hours acts as a trigger, signaling the appropriate time to commit energy to flower and pod production. The plant continues to produce blossoms in successive flushes throughout the warm season, allowing for a continuous harvest.
Pollination and Pod Formation
Pod formation is largely due to the flower’s self-pollinating nature, a mechanism known as cleistogamy. Since the reproductive organs are fully encased within the keel, the flower is genetically predisposed to fertilize itself. The anthers release their pollen directly onto the stigma of the same flower, ensuring seed set.
Once successful fertilization occurs, the fertilized ovary, situated at the base of the pistil, begins its transformation into the edible pod. The flower’s petals quickly wilt and drop away as the ovary wall elongates and expands. The young pod starts to accumulate nutrients within about six days after pollination.
By 10 days post-pollination, the seeds are in an active filling phase, accumulating starches and proteins. The pod is ready for fresh consumption as a “snap” or “shell” pea when it is green and plump, typically 60 to 70 days after planting. For dry bean harvest, the process continues until 80 to 100 days after planting, when the pod wall has dried, turned brown, and the mature seeds inside have undergone desiccation for long-term storage.