While commonly grouped under the name "geranium," the plants we cultivate in our gardens and homes belong almost exclusively to the genus *Pelargonium*. True geraniums are the hardy, herbaceous plants of the genus *Geranium*. This distinction is crucial from a botanical standpoint. The popular "geraniums" discussed here are tender perennials native primarily to South Africa, valued for their vibrant flowers, foliage, and aromas. Their differences lie in their growth habits, leaf morphology, floral structure, and primary uses.
Zonal Geraniums are the most recognizable type, widely used in bedding schemes and container gardens. Botanically, they are complex hybrids, primarily derived from species like *Pelargonium zonale* and *Pelargonium inquinans*. Their name originates from the often horseshoe-shaped, dark "zone" or band of pigmentation on their rounded, velvety leaves. This zoning is caused by anthocyanin pigments. The leaves are typically peltate, meaning the leaf stalk attaches to the center of the leaf blade rather than the edge. The flowers are borne in large, spherical umbels held high above the foliage on sturdy stems. A key botanical characteristic is their flower structure: they typically possess five petals, with the two upper petals often being larger and differently marked than the three lower ones. Zonal geraniums are primarily bred for prolific and long-lasting floral displays and are classified as upright, self-branching shrubs.
Ivy Geraniums are distinct in both form and origin. They are derived from a single species, *Pelargonium peltatum*, which gives them their defining growth characteristic: a trailing or cascading habit. This makes them exceptionally well-suited for hanging baskets, window boxes, and wall plantings. Their leaves are the most telling feature; they are glossy, succulent-like, and ivy-shaped (peltate with lobed margins), lacking the fuzzy texture and dark zoning of their zonal counterparts. The flowers are also borne in umbels but are generally looser and more informal in structure than the tight globes of zonal types. The individual flower petals are often narrower, and the blooms tend to face outward or downward, following the direction of the trailing stems. From a botanical perspective, their adaptation for sprawling and climbing in their native habitat is their most significant differentiator.
Scented Geraniums are not a single type but a diverse group of species and cultivars selected and hybridized primarily for their fragrant foliage, not their often-inconspicuous flowers. The aromatic oils are contained in glandular trichomes (tiny hairs) on the leaves, which release their scent when brushed or crushed. The botanical diversity here is immense. Leaf shapes vary dramatically and can be deeply lobed, finely dissected, rounded, or crinkled. The range of scents is equally vast, including rose (*Pelargonium graveolens*), lemon (*Pelargonium crispum*), mint, coconut, and even nutmeg. Their growth habits are also varied, ranging from small, upright shrubs to sprawling plants. Unlike the other two types, the value of a scented geranium lies in its chemical composition and the sensory experience of its foliage, making it a plant for herb gardens, sensory gardens, and as a fragrant potted specimen.
