- DIVISION: Tracheophyta
- CLASS: Liliopsida (monocots)
- ORDER: Zingiberales
- FAMILY: Zingiberaceae
- GENUS: About 50
- SPECIES: Almost 1,600
Yep, the ginger in your gingerbread comes from this family of plants. But it's their elegant bloom clusters and intoxicating scent that make these mostly tropical perennials favorites in the greenhouse, in the garden, or in displays of cut flowers. Ginger flowers come in an amazing variety of shapes and sizes. Nearly 1,600 species in this family grow throughout tropical Africa, Asia, and the Americas. Some, like Aframomum giganteum of Central Africa and Etlingera punicea of Indonesia, stretch to 20 feet (6.1 meters) tall, but most familiar gingers are about 6 feet (1.8 meters) tall. Depending on species, a ginger's fragrant blossoms are pollinated by insects or birds.
The spicy ginger "root" you might purchase in your local market is really a section of a ginger plant's fleshy rhizome—a horizontal underground stem. Continuously growing rhizomes allow a ginger plant to ramble and spread, sending down roots and sending up tall leafy shoots. Narrow, glossy leaves, which grow alternately in two rows, have parallel veins. Ginger flowers grow in clusters. Each grows in the axil of a modified—sometimes brightly colored—leaf called a bract and bears both male and female organs. A single pistil (female organ) is surrounded by a single functional stamen (male organ). Five sterile stamens are modified; some are fused and look like petals, while the actual petals and sepals are fused into tubular structures. In some species, a seed may sprout into a miniature plant as a flower withers, taking root where the flower falls to the ground.
While some gingers are hardy enough to grow in temperate gardens, most are tropical plants that require warm temperatures. They require filtered sun, high humidity; moist, rich soil; and temperatures above 50 degrees Fahrenheit (10 degrees Celsius). Still, many gardeners in colder places enjoy growing ginger in the spring and summer. As the foliage withers in winter, they dig up the rhizome, allow it to dry out, and store it in sawdust or sphagnum—as you might store a tropical bulb.
Ornamental gingers are attractive in warm-climate gardens, and flowers are lovely in arrangements. But many species are better known (and grown) for spices and medicines. The spice we use in gingerbread is the same one we use in Asian cooking: Zingiber officinale, sometimes called "true" ginger. Galangal, a spice used in some Asian recipes, and melegueta pepper, common in the cuisine in parts of Africa, come from different ginger species. Perhaps more familiar, turmeric and cardamom come from gingers, too. Many ginger species are used in traditional folk medicines, and as you might expect from their sweet scent, some species yield essential oils used in the perfume industry.
The IUCN has assessed 104 species of gingers, and lists 30 species as vulnerable or endangered, including 4 species that are critically endangered. The most common threats to the survival of these species include agriculture, logging, and collection of plants from the wild. Ornamental gingers and those used for folk remedies are now commercially traded, often leading to unsustainable harvests of wild plants. The Philippine ginger Lily Hedychium philippinense is listed on CITES Appendix II.
Sometimes gingers create conservation concerns: in some tropical places, including as Hawaii, ornamental gingers have flourished and have become invasive species that displace the native plant communities.
You'll find a spectacular collection of gingers, including true ginger Zingiber officinale, at the San Diego Zoo as you travel down the Fern Canyon Trail into Asian Passage. The grandest may be the shell ginger Alpinia zerumbet, native to eastern Asia. Beautiful pendants of shell-like flower grow in late summer. And don't miss the fragrant white butterfly ginger Hedychium coronarium, or the spectacular, yellow-flowering kahili ginger Hedychium gardnerianum, native to India. Unfortunately, kahili ginger has become an invasive species in Hawaii and other places it has been introduced. (San Diegans can grow kahili ginger with a clear conscience, however. It's not humid enough here for the plant to spread out of control on its own.)