Cyrtandra

Cyrtandra

Full name and orig. publication: Cyrtandra J.R. & G.Forst., Char. gen. pl. 5 (1776).

Etymology: From the Greek κυρτος, kyrtos = curved, tortuous, and ανδρος, andros = male, alluding to the curved filaments of the stamens.

Synonyms: Rhynchocarpus Reinw. ex Blume (1823), Whitia Blume (1823), Getonia Banks & Sol. (1838), Cyrtandropsis Lauterb. (1910), Protocyrtandra Hosok. (1934), Cyrtandroidea F.Br. (1935), ? Sepikea Schltr. (see there).

Infrafamilial position: Didymocarpoideae-Trichosporeae-Didymocarpinae (Weber et al. 2013).

Description: Shrubs or lignescent herbs, sometimes small trees. Stem terete or angular, usually erect or ascending, branched or unbranched. Leaves opposite, iso- to strongly anisophyllous; petiole short to long, lamina of variable shape, ranging from narrow lanceolate to suborbicular, margin entire or dentate, venation pinnate. Cymes axillary, shortly to long pedunculate, placed in upper or lower (leafless) part of stem, sometimes growing underground; bracteoles free, sometimes connate and forming a conspicuous cup; flowers in dense clusters or in open cymes or solitary. Sepals 5, free or connate, calyx sometimes bilabiate, persistent or caducous. Corolla variously (usually light-)coloured, funnel-form, campanulate or tubular, limb bilabiate, rarely (sub)regular, lobes rounded. Stamen usually two, the anterior ones, rarely 4 (the former genera Protocyrtandra and Cyrtandroidea) included or (rarely) exserted; anthers free or coherent, thecae subparallel, sometimes apically confluent, dehiscing longicidally; staminodes 2-3. Nectary ring- or cup-shaped, often persistent in fruit. Ovary ovoid to oblong, unilocular, placentae recurved; style long or short; stigma capitate or bilobed. Fruit indehiscent, oblong, ovoid or globose, hard-walled (sclerocarpous), leathery or fleshy.

Chromosome number: 2n = 34 (rarely 32?).

Species number: The species numbers given in the literature differ greatly. The most recent estimate was by Atkins et al. (2013), giving a number of over 800 species. Cyrtandra is by far the most species-rich genus in the Gesneriaceae.

Species names (given only in case of few species).

Type species: Cyrtandra biflora J.R. & G. Forst.

Distribution: Ranging from the Nicobar Islands and S Thailand through Malesia and the S Pacific to the Hawaiian Islands.

Ecology: Terrestrial plants of lowland and montane rain forests.

Notes: The northernmost outlier of the genus is C. umbellifera (Southern Ryukyo Islands, Taiwan, Philippines). Centres of diversity are Borneo, New Guinea and the Pacific Islands. Cyrtandra is the largest genus of Gesneriaceae and the genus with widest distribution in the Old World. The main distinctive character is the indehiscent fruit, which is hard as stone (sclerocarpous) predominantly in the Western species and soft-fleshy (a true berry) in the eastern (Pacific) species. A conspicuous anatomical character of many species is the presence of sclereids (osteo- and/or astrosclereids) in the hypodermis and mesophyll of the leaves. There is a continuous range from iso- to extreme anisophylly (the smaller leaf of a pair being reduced to a tiny, triangular scale, e.g., C. dispar, C. baileyi). In the inflorescences the flowers are usually densely aggregated, and the bracteoles are sometimes enlarged and fused to form a conspicuous cup. Sometimes the flowers are placed at the ground by the elongation and downcurving of the peduncle or emerge from the soil in that the elongated cyme is buried in the ground (geoflory; some species from Borneo and Sulawesi, e.g., C. rhizantha). The usually light-coloured flowers indicate melittophily; species with red or reddish flower colour (e.g., C. clarkei) are possibly ornithophilous. Nothing is known about the dispersal of the sclerocarpous fruits, while the fleshy berries are clearly bird-dispersed. Cyrtandra is polymorphic throughout its range and species delimitation is very difficult. Especially in the Hawaiian Islands variation is extreme. This led St. John (Phytologia 63-65: 1987-1988) to describe more than 250 new species, while a more realistic total species number in Hawaii is around 60. The extreme polymorphism is the result of extensive interspecific, and usually intersectional, hybridisation (Wagner & al. 1990, Smith & al. 1995). A natural subdivision has not been achieved yet. Clarke (1883) subdivided the genus (with 157 species then known) into two subgenera and 13 sections:
(A) subg. Brachycyathus (1) sect. Dispares, (2) sect. Whitia, (3) sect. Stellatae, (4) sect. Cupreatae, (5) sect. Apertae, (6) sect. Macrosepalae, (B) subg. Cytrandra ("Macrocyathus") (7) sect. Campanulaceae, (8) sect. Decurrentes, (9) sect. Jackianae, (10) sect. Dissimiles, (11) sect. Coccineae, (12) sect. Aureae, (13) sect. Polynesieae. With regard to the Hawaiian species Wagner & al. (1990) recognized the following sections: (1) sect. Verticillatae, (2) sect. Cylindrocalyces, (3) sect. Crotonocalyxes, (4) sect. Apertae, (5) sect. Macrosepalae, (6) sect. Chaetocalyces.
A new section, Pleuroschisma, was recently established by Hilliard et al. (2003). Sect. Dissimiles was recently revised by Bramley (2005). Many species from Borneo have been described by O.M.Hilliard and B.L.Burtt in Edinburgh J. Bot.
A summary of the present knowledge and discussion of future research directions in the taxonomy of Cyrtandra can be found in Atkins et al. (2013). A most important molecular-phylogenetic study was recently published by Atkins et al. (2020), discussing aspects of origin, historical and present distribution, migration routes etd. of Cyrtandra.

Selected references: C.B.Clarke in A. & C. DC., Monogr. phan. 5(1): 201-287 (1883), rev.; Bokhari & Burtt, Notes Roy. Bot. Gard. Edinburgh 30: 11-21 (1969), anat.; Burtt, Edinburgh J. Bot. 47: 201-233 (1990) and 49: 285-296 ([1992] 1993), new spp.; Backer & Bakh.f., Fl. Java 2: 543 (1965), reg. rev. (Java); Gillett, Contr. US. Natl. Herb. 37: 107-159 (1967), reg. rev. (Fiji); Gillett, J. Arnold Arbor. 54: 105-110 (1973), reg. rev. (Ryukyu and Caroline Islands); Gillett, Univ. Calif. Publ. Bot. 66: 1-59 (1973), reg. rev. (South Pacific); Roelofs, Pacific Sci. 33: 223-231 (1980), repr. biol.; St. John, Bernice P. Bishop Mus. Bull. 229: 1-465 (1988), reg. rev. (Oahu); Wagner, Herbst & Sohmer, Manual of Flowering Plants of Hawaii 1: 735-781 (1990), reg. rev. (Hawaii); Samuel, Pinsker & Kiehn, Bot. Acta 110: 503-510 (1997), molec. syst.; Wang et al. in Wu & Raven, Fl. China 18: 395 (1998) (Chinese spp.); Atkins et al., Biol. J. Linn. Soc. 72: 143-159 (2001), molec. syst. of Bornean & Philipp. spp.; Atkins et al., Edinburgh J. Bot. 58, 443-458 (2001), reg. rev. Palawan/Philippines; Burtt, Phytomorphology, Golden Jubilee Issue 2001: 393-404 (2001); Burtt, Thai Forest Bull. (Botany) 29: 81-109 (2001), annot. checklist (Thailand); Hilliard, Burtt, Bokhari, Garden's Bull. Singapore 55: 35-60 (2003), new sect.; Bramley, Blumea 50: 163-189 (2005), rev. of sect. Dissimiles. Atkins et al., Selbyana 31: 157-165 (2013), general consid., spec. number; Atkins et al., Frontiers Biogeogr. 2020, 12.1., 44814, molec. syst., biogeogr.

Tax. details, cytology, and bibliography: Gesneriaceae Resource Centre (GRC). Royal Botanic Garden Edinburgh.

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