Chirita is one of the larger Old World genera of Gesneriaceae, with about 150 species ranging from Sri Lanka and India through the Himalayas into China and Southeast Asia down the Malay Peninsula, with a very few species reaching the islands of Sumatra, Java, and Borneo (see map). The genus is not represented at all in Africa, Australia, Japan, or the Philippines. The plants can be shrubby perennial herbs, soft-stemmed annual herbs, stemless perennial rosettes, or diminutive herbs with only one or two leaves. Many of the species grow on rocky hillsides or cliffs, often on limestone. Chirita species differ from several Old World genera by having two fertile stamens rather than four, from Streptocarpus in having straight, rather than twisted fruit, and from Didymocarpus in having a lamellate, usually bilobed, stigma. Species of the related genus Chiritopsis have a very short fruit, unlike the elongated capsule of species of Chirita. Primulina tabacum is another close relative, and there are several small genera in China that are probably also related. Many Chirita species have beautiful flowers and are of easy culture, and are becoming increasingly popular with gesneriad hobbyists. Many of these species have only been introduced to cultivation within the last ten years.
Taxonomy and Nomenclature
Chirita was originally described in 1822 by D. Don for a small group of Himalayan herbs, based on an unpublished manuscript name by Buchanan-Hamilton. The name "Chirita" is derived from the vernacular name of one of the species. The genus was distinguished from Streptocarpus by having a straight fruit and from Didymocarpus by having a bilobed stigma. Since then, both Didymocarpus and Chirita have grown considerably, and the distinction between them has become less clear, leading some taxonomists to consider Chirita to be a synonym of Didymocarpus (or Roettlera or Henckelia, two rejected names for Didymocarpus). Genera that have been synonymized under Chirita include Calosacme, Tromsdorffia, Babactes, Liebigia, Mortsdorffia, Bilabium, Gonatostemon, Damrongia, Ceratoscyphus, and Deltocheilos. "Chirata" is a rejected variant spelling of the generic name.
Since the original description included several species but did not indicate one as the type of the genus, B.L. Burtt selected the Himalayan Chirita urticifolia from among the original group as the type species in 1954. The entire genus was revised by D. Wood in 1974 but this revision suffered from inadequate herbarium and live material. Wood predicted, quite correctly, that a large number of new species would be discovered in southern China. In 1975, Prof. Wang Wen-tsai and his colleagues in China began revising the Chinese species. The treatment of Gesneriaceae for the soon-to-be-published Flora of China (English edition) will include 99 species of Chirita, almost 70 of them described since 1980. The Flora of China project has an excellent web site, well worth visiting in its own right, even though the Gesneriad content is not yet available on the site.
Chirita is currently divided into three sections: Chirita, Microchirita, and Gibbosaccus. This division is based on differences in morphological characters, with section Chirita, by definition, containing C. urticifolia, the type species of the genus. These three groups are quite different from one another, and a determined splitter could easily recognize them as three distinct genera.
Section Chirita, with about 45 species, is the most heterogeneous of the three sections and has the widest geographic range, but is represented by the fewest species in cultivation. The species are usually caulescent perennial herbs or even small shrubs, but some are diminutive herbs with only one or two leaves. One distinguishing characteristic of this section is that in many species the calyx lobes are more or less fused into a tube. The flowers are often large and showy.
There are several subgroups within section Chirita. One group of species on Sri Lanka includes the shrubby species C. moonii, C. walkerae, and C. zeylanica. The species from the Himalayan region are usually small herbs, and are represented in cultivation by C. hookeri. Two wide-ranging annuals are C. pumila, which occurs from northern India to Southeast Asia, and C. anachoreta, found throughout Southeast Asia. Chirita asperifolia was noted by Wood as one of the more taxonomically isolated members of this section. Besides some morphological differences, it is unusual in coming from the islands of Java and Sumatra. There are several other unusual and very interesting species that are not yet in cultivation. Known chromosome numbers of species in section Chirita are n = 4, 9, 10, 14, and 16.
Section Microchirita consists of about 20 species of caulescent annual, rarely perennial, herbs. Many of the species have a rather unusual inflorescence structure, with the flowers appearing from the leaf petioles. Some will bloom from the enlarging cotyledon without ever developing any further stems or leaves. This group is primarily tropical and is best represented in Southeast Asia, especially Thailand and Vietnam. Species in cultivation are C. caliginosa, C. elphinstonia, C. hamosa, C. involucrata, C. lavandulacea, and C. micromusa and C. sericea. Known chromosome numbers are n = 9 and 17.
Section Gibbosaccus has about 80 species that are restricted to southern China and northern Vietnam. Most species, including all now in cultivation, are acaulescent rosettes, some rather reminiscent of Saintpaulia (although, like Saintpaulia, many will produce a long "neck" with age). Most grow on rocky limestone hills and cliffs, and many are tolerant of cool temperatures in cultivation. Of the three sections, Gibbosaccus has the most species in cultivation, but until about ten years ago had the fewest. The best-known species, C. sinensis, has been in cultivation in the United States for only thirty years or so. Many Chinese species have recently been introduced to cultivation in the United States through the Smithsonian Institution, thanks to the collaboration between Larry Skog and several Chinese scientists working on the Flora of China, and through Japanese AGGS members Nagahide Nakayama and Toshijiro Okuto.
The cultivated species of section Gibbosaccus fall into several groups. The C. sinensis group is characterized by large, leafy bracts that enclose the developing buds. Chirita sinensis is a variable species with many different leaf shapes, some with silver markings. Besides C. sinensis, species in cultivation include C. eburnea and C. spadiciformis. Plants identified as the blue-flowered form of C. eburnea may actually be a separate species. The C. linearifolia group, which includes C. longgangensis, are compact species with narrow leaves, often produced on a long trunk-like "neck". A group of large-growing species that are related to C. pteropoda are C. flavimaculata, C. heterotricha, and C. sp. New York (previously misidentified in cultivation as C. pteropoda). Other species in cultivation that do not seem to be closely related are C. fimbrisepala, C. sclerophylla, and C. subrhomboidea. Several species of section Gibbosaccus are now being used to produce interspecific hybrids, many of which will be introduced as named cultivars within the next two years. Two of these, created by Toshijiro Okuto of Japan, are C. 'Aiko' (C. eburnea x C. subrhomboidea) and C. 'Keiko' (C. subrhomboidea x C. fimbrisepala). Formal descriptions of these hybrids will likely be published in CrossWords, the newsletter of the Gesneriad Hybridizers' Association (see Gesneriad Links for membership information). The only known chromosome number for a member of section Gibbosaccus is n = 18 for C. sinensis.