Pelargoniums: An Herb Society of America Guide

Description

Pelargoniums are a diverse group of plants with a wide variety of growth habits and habitats. Members of the family Geraniaceae, estimates of the total number of species and subspecies in the genus range from 230-300 (10, 63, 64, 83, 90, 94). Most are native to southern Africa (14, 90), but a few species occur naturally in Australia, eastern Africa, New Zealand, the Middle East and the islands of Madagascar, St. Helena, and Tristan de 
Cuhna (63, 64). Pelargonium height typically ranges from 1 to 6 feet (90) depending on species, hybrid or cultivar, but some species may grow even taller in their native habitats. 

The genus Pelargonium includes annuals and herbaceous perennials, shrubs and subshrubs, and both evergreen and deciduous plants (63, 64), but most of the scented-leafed species or “scenteds” are succulent perennial shrubs in their native habitats (87). One notable exception is P. grossularioides, the coconut-scented Pelargonium, which is an annual (90). Some species have spiny stems (63), and many have stems that are initially herbaceous but become woody with age (90). Some grow erect while others have a 
trailing habit, and some have tuberous roots (4, 90). Pelargoniums grow in areas with low rainfall and low humidity (10, 63) in a variety of habitats, from rocky slopes to grasslands, forests and along streams (10, 63, 90).

Most herb enthusiasts value pelargoniums for their fragrant leaves, but not all plants in the genus are scented, and not all of the scents are pleasant. Pelargoniums are informally 
classified as zonals (which are named for the dark markings on the leaf surface (85, 103) and are primarily ornamental, bedding plants), fancy-leaf cultivars (some of which are scented), regals, angels, ivy-leaf, and scented-leaf (15). (See Taxonomy section for formal classification.) The scented-leafed pelargoniums can have aromas of rose, peppermint, lemon, lime, orange, strawberry, camphor, nutmeg, spice, apricot, apple, filbert, ginger, and coconut (90). Plants are often categorized by enthusiasts according to the following scent groups: citrus, fruit and nut, mint, rose, and pungent (10, 15). Sensitive noses may detect a hint of pungency in all of the scent groups (12). Although fragrant-leafed pelargoniums are commonly called scented geraniums, true geraniums are actually in a separate genus in the Geraniaceae family that is native to Europe, North America and Asia (64).

Assorted Pelargonium leaves

Pelargonium leaves come in a variety of shapes and sizes and may resemble ferns, grape leaves or oak leaves and may be deeply divided or nearly round. They may be small or large, may be covered with fine hairs and may be rough, sticky or have a velvety texture (10). Leaf edges may appear "curly" or "crisped" in some species (4). Leaves include scent glands that release pelargoniums’ renowned scents when brushed (15), may be 
variegated, and may include dark patches of color in the center (10) or along the veins (5). 

Although some hybrids have 8-10 petals and are known as "double-flowered," most scented Pelargonium flowers have 5 petals (2 upper and 3 lower), and these pelargoniums are considered "single-flowered" (10). The arrangement of the petals distinguishes pelargoniums from other members of the family Geraniaceae (6). Flowers occur in a pseudo-umbel consisting of 1-50 individual flowers (64), but most have 5-10 florets (10). Flowers may be white, pink, mauve (4), lavender, pale yellow or burgundy, and upper petals may have purple, pink (4) or red markings (10). Although the flowers of most pelargoniums are not scented, a few species, like P. triste, have flowers that emit a scent, but only at night. Most of the scented-leaf species have small, delicate blooms, but some pelargoniums have flowers that resemble tulips, carnations, cactus flowers or pansies (15).

The genus name derives from the Greek word for stork, "pelargos," due to the resemblance of the seed pod/fruit to the head and bill of a stork (14, 64, 90). Plants in the genus are often given the common name storksbill for this reason (90).

Next section: Taxonomy

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