A watermelon seedling (Citrullus lanatus) is the young plant emerging from the seed, representing the earliest stage of growth. Accurately identifying this seedling is important for any gardener attempting to cultivate the popular summer fruit. The visual characteristics of the early growth stages, particularly the first leaves, provide the most reliable clues for distinguishing a watermelon plant from other sprouts. This identification focuses on the temporary first leaves and the distinct shape of the subsequent true leaves.
The Initial Sprout: Cotyledon Leaves
The first pair of leaves to emerge from the soil are the cotyledons, or seed leaves, which look completely different from the mature foliage. These initial leaves are generally broad and slightly oblong or oval-shaped, often exhibiting a smooth, waxy surface. They are relatively thick and store food reserves to sustain the young plant before it can begin efficient photosynthesis. Watermelon cotyledons, typical of the Cucurbitaceae family, are large and may appear somewhat spatula-like, sometimes with a subtle heart-shaped base. They emerge opposite each other on a short stem and are typically a vibrant, uniform light green color. These cotyledons are temporary structures that will eventually yellow and drop off once the plant establishes its permanent leaves.
Identifying the True Leaves
The definitive identification of a young watermelon plant occurs with the appearance of the second set of leaves, known as the true leaves. These leaves emerge from the growing point, or epicotyl, located between the two cotyledons. They are the first leaves that resemble the characteristic foliage of the mature Citrullus lanatus vine, though they are much smaller.
The true leaves are characterized by a deeply lobed or indented structure, often having three to five major lobes. This intricate, jagged appearance is a sharp contrast to the smooth, simple shape of the cotyledons. The color is typically a darker, richer green, and they may possess a slightly rough or fuzzy texture. The distinct lobed structure serves as the most reliable visual identifier, setting the watermelon seedling apart from other sprouts. This morphological change indicates the seedling has transitioned to self-sustained growth.
Key Characteristics of Early Growth
Beyond the foliage, the stem and growth habit provide further clues for identifying a young watermelon seedling. The stem is generally sturdy, slightly angular, and often covered with fine, pale hairs, which is particularly noticeable on new growth. This woolly appearance is a characteristic of the species Citrullus lanatus, where the specific epithet lanatus translates to “woolly.”
The overall color of the young plant is a bright to medium green, and the initial growth pattern is compact and upright. As the seedling matures, it quickly adopts a sprawling, vining habit, sending out long runners along the ground. The presence of these hairy, trailing stems helps to distinguish the young watermelon from smooth-stemmed garden weeds.