Gesnerias

Members of the Gesneria family, the Gesneriaceae, are herbs, shrubs, sometimes trees or woody vines. The Gesneriaceae is a large family composed of approximately 120 genera and 1,800 species. With the exception of two genera (Haberlea and Ramonda), which are native to temperate Europe, they are found only in the tropical and subtropical regions of the world. Although none are native to the United States, more than a dozen genera are found in Mexico.

These plants have simple leaves that are opposite or grow in rosette form around the base. The flowers are showy and borne solitary or in flower clusters that bloom from the center outward. The flower petals have five lobes, and are often fused at the base to form a tubular corolla. The fruit is usually a capsule, but in some species it is fleshy and berrylike. Numerous tiny seeds are produced. Taxonomically, the family is closely allied to the Scrophulariaceae, the Snapdragon family, the Bignoniaceae, the Trumpet-vine family, and the Orobanchaceae, the Broom-rape family.

Gesneria, the genus for which the family is named, contains about 50 species native to the forests of tropical America, found on the mainland and islands of the West Indies. The genus was named after the Swiss naturalist Conrad Gesner (1516-1565) by Charles Plumier (1646-1704), a French missionary, botanist, and explorer, who published a book about the Caribbean Islands he visited in 1703. Gesneria species are characterized by their long red and green tubular flowers that co-evolved with their special pollinators, hummingbirds and bats. Hummingbirds Kohleria, a genus of gesneriad. Photograph by James Sikkema. Reproduced by permission.
are well adapted to extracting nectar from flowers by their ability to hover, their visual acuity for red, their long bill and tongue. Since flower-feeding bats are not visually sensitive to color, bat pollinated Gesneria species are green. They produce abundant nectar with a fruity odor attractive to bats.

Members of the Gesneria family are important economically as ornamentals that are grown outside in warm tropical climates, and in greenhouses in cooler climates. The genera Ramonda and Haberlea are prized plants for rock gardens in temperate regions. Popular ornamentals include the African-violet (Saintpaulia), gloxinias (Sinningia), Cape primrose (Streptocarpus), and others. African violets are a popular houseplant prized for their attractive leaves and profuse blooms that range in color from white to pink, lavender, and dark purple. They also come in a variety of variegated colors and different flower types, from single to double with simple or ruffled petals. They are native to the tropical lowlands of East Africa. Gloxinias have much larger, red or purple bell-shaped flowers, and are native to Brazil.