Cleome, commonly known as Spider Flower, is a popular annual plant prized for its tall, airy texture and long-lasting summer blooms. These plants (Cleome hassleriana) are often grown from seed, either by direct sowing or starting indoors. Identifying the plant early is important for thinning and distinguishing it from unwanted weeds, especially since it often self-seeds aggressively. Knowing the visual cues of a young Cleome seedling allows a gardener to cultivate the desired flowers.
Initial Appearance of Cotyledons
The first leaves to emerge after germination are the cotyledons, or seed leaves, which offer the first chance at identification. Cleome cotyledons are typically small, delicate, and uniform, bearing no resemblance to the mature foliage. They present as a pair of simple leaves, often smooth and a bright, consistent shade of green. These structures are temporary and primarily provide the seedling with nutrients until the true leaves begin photosynthesis.
The cotyledons are commonly oval, oblong, or slightly kidney-shaped. While they confirm germination, they are not distinctive enough to rule out other garden plants or weeds. They emerge on a tiny stem close to the soil surface, but this stage is brief as the plant quickly focuses on developing the true leaves.
Characteristics of True Leaves
The emergence of true leaves marks the point where the Cleome seedling displays its unique identity. These structures develop above the cotyledons and are the first to exhibit the plant’s distinctive compound structure. The true leaves are palmate, meaning they are divided into several leaflets radiating from a central point. This palmate structure is the most reliable visual confirmation that a young plant is a Cleome.
A typical young Cleome true leaf consists of five to seven separate, slender leaflets. These leaflets are often narrowly ovate or lance-shaped, tapering slightly where they connect to the petiole. The color is usually a medium to deep green, though some varieties may show a purple tint along the edges or veins. Unlike the smooth cotyledons, the true leaves and petioles may already exhibit a slightly hairy or glandular texture, which precedes the fuzzy stems of the mature plant.
Practical Tips for Identification
The rapid growth habit of Cleome is a key indicator after the true leaves emerge. Seedlings grow quickly, establishing a stout taproot and gaining height rapidly compared to slower-growing garden plants. The developing stem is often light green and covered in glandular hairs, giving it a slightly fuzzy or sticky feel. Depending on the cultivar, the stem may also have a reddish or purple-tinged coloration.
A specific characteristic is the scent of the foliage. Many traditional Cleome varieties possess glandular hairs that release a distinct, musky, or pungent odor when the leaves are crushed. While modern hybrids like the ‘Señorita’ series are bred to be odorless, self-sowing varieties often have this faint, skunk-like fragrance that serves as a unique identifier. Distinguishing Cleome from common weeds is simplified by checking for the palmate leaf structure, as few garden weeds share this distinctive 5-to-7 leaflet pattern.