The tobacco plant, known scientifically as Nicotiana tabacum, is a member of the diverse nightshade family, Solanaceae, which also includes common plants like tomatoes and potatoes. This specific species is the one primarily grown for commercial use across the world. The plant is generally cultivated as an annual, completing its life cycle in a single growing season, though it is technically a tender perennial in warm, tropical climates. Identifying N. tabacum relies on recognizing its distinct architecture, characteristic foliage, and reproductive structures, all of which contribute to its imposing presence in the field.
Overall Growth Habit and Stem Structure
The tobacco plant is a robust, herbaceous organism that can quickly achieve an impressive stature. It typically reaches a height of 3 to 6 feet, with some varieties even growing taller than this range. This substantial vertical growth is supported by a thick, stout central stem that is generally unbranched until it culminates in the flowering head.
The stem is noticeably covered in fine, sticky hairs, a feature shared by the rest of the plant’s above-ground structures. While the plant mass above ground is significant, it is anchored by a taproot system that develops lateral fibrous roots to provide stability. The overall growth habit is upright and somewhat lanky, establishing a large, leafy structure that dominates its growing space.
Identifying the Leaves
The foliage of Nicotiana tabacum is its most defining feature, distinguishing it from most other cultivated plants. The leaves are very large, often exceeding one or two feet in length. Their shape is typically described as ovate to elliptical or lanceolate, meaning they are broad and taper to a point.
The leaf arrangement is alternate, with a single leaf arising at each node spiraling up the stem. Lower leaves may possess a short, winged stalk (petiole), but the upper leaves tend to be sessile or clasping, appearing to grow directly from the stalk. A characteristic pale or bluish-green color covers the leaf surface, which is also glandular pubescent, meaning it is covered in numerous fine, sticky hairs.
The sticky texture results from glandular hairs secreting a viscous substance onto the leaf surface. This secretion is significant because it is where the plant’s alkaloid, nicotine, is produced and concentrated. The leaves at the base of the plant are the largest, with their size gradually decreasing as they ascend the main stem.
Flowers and Reproductive Structures
The flowering structures emerge as a terminal cluster situated at the very top of the central stem. The flowers themselves are relatively delicate in appearance compared to the massive leaves below them. They are elongated and tubular, often described as trumpet-shaped, and are typically five-lobed at the opening.
The corolla, or fused petals, is generally a greenish-cream color with lobes that can range from pink to white or occasionally red. After the flowers are pollinated, a small, two-valved capsule or pod develops, which is the plant’s fruit. This capsule contains numerous tiny seeds, allowing the plant to produce a large number of offspring.