Neotropical Rubiaceae

Daniela Zappi

Royal Botanic Gardens, Kew, UK. 

Description

Herbs, climbers, lianas, shrubs, trees, usually understorey shrubs. Leaves opposite, sometimes whorled, entire, linked by interpetiolar (sometimes intrapetiolar) stipules of varied shapes and sizes, with colleters within. Inflorescences variable, panicles, cymes, racemes, fascicles, terminal or axillary, sometimes flowers solitary, bracts often present, sometimes corolline or involucral. Flowers 4-5(-6-12) merous, hermaphrodite or bisexual, often heterostylic or with secondary pollen presentation (when bisexual); calyx fused with hypanthium, free part tubular or lobed, sometimes very short, in some genera one calyx-lobe developed as a semaphyll; corolla gamopetalous, aestivation valvate, imbricate, contorted, mostly radial (rarely zygomorphic), small to 15(-30) cm long, white, cream, yellow, pink, blue, red, violet or mauve, sometimes bi-coloured, glabrous to hairy outside or within, stamens alternate to the corolla-lobes, stigma undivided to more commonly 2-lobed. Fruits capsular, berry-like or drupaceous with 1-many pyrenes; seeds 1-numerous, rounded, angled or winged.

Notes on delimitation

  • Includes Dialypetalanthus Kuhlm. (formerly Dialypetalanthaceae).

Distribution in the Neotropics

  • Throughout the Neotropics, 3rd to 5th family in number of species in tropical forests.

Distinguishing characters (always present)

Other important characters

  • Colleters in the inside of stipules and calyx.
  • Secondary pollen presentation in Gardenieae.
  • Herbs with varied capsular fruits in Spermacoceae.
  • Pyrenes and raphids in some groups.

Key differences from similar families

Number of genera

  • 637 genera and over 10,000 species worldwide, of which approximately 220 genera and 4,500 species are Neotropical.

Useful tips for generic identification

Notable genera and distinguishing features

  • Psychotria L.: shrubby to tree-like, bilobed or rounded stipules, corolla tube straight, flowers small, white, cream or yellow, fruits 2-5-seeded, fleshy.
  • Palicourea Aubl.: shrubs to treelets, bilobed to bifid stipules, flowers colourful, corolla tube gibbose, fruits 2-5-seeded, fleshy.
  • Borreria (= Spermacoce): herbs to subshrubs, stipules fringed, flowers tetramerous, 2-seeded capsules.
  • Cinchona: trees, corolla long, pinkish, many ovules per locule, seeds winged in capsules.
  • Genipa L.: trees, pre-floration contorted, flowers bisexual, secondary pollen presentation, large berries with fleshy pulp.
  • Mannetia: twining climber with showy flowers, many-seeded capsular fruit.
  • Rudgea Salisb.: shrubs to trees, stipules fringed to appendiculate, corolla tube straight, often longer than Psychotria.
  • Faramea Aubl.: shrubs to trees, stipules aristate or triangular, flowers blue, fruits 1-seeded.

Status

  • Exotic species of Ixora L. from China
  • Several species and cultivars of Mussaenda L., Gardenia jasminoides Ellis and Pentas lanceolata Schum. are widely cultivated ornamental plants in the Neotropics.
  • Species of cultivated Coffea L. commonly escape into forests near farms in Brazil.
  • Species of Cinchona L. cultivated for quinine have been introduced in many tropical countries.
  • Genipa americana L. is cultivated throughout South America for edible fruits and dye.
  • Weedy genera such as Galium L., Borreria G.Mey., Diodia L., Richardia L. and Mitracarpus Zucc. have distribution sometimes worldwide.
  • Endemic genera in the Caribbean are often monotypic.

General notes

  • One of the most important plant families from the Neotropics, it occupies between 3rd and 5th place in species richness in tropical forests.

Important literature

Andersson, L. 1992. A Provisional Checklist of Neotropical Rubiaceae. Scripta Botanica Belgica 1.

Müller, J. 1881–1888. Rubiaceae. In Martius, C.F.P. von (ed.). Fl. bras. 6(5):  1–486. Fleischer, Leipzig.

Schumann, K. 1888–1889. Rubiaceae. In Martius, C.F.P. von & Eichler, A.G (eds.). Fl. bras. 6(6): 1–466. Fleischer, Leipzig.

Taylor, C.M., Steyermark, J.A., Delprete, P.G., Vincentini, A., Cortés, R., Zappi, D., Persson, C., Costa, C.B. & Anunciação, E. 2004. Rubiaceae. In: Steyermark, J.A., Berry, P.E., Yatskievych, K., & Holst, B.K. (eds.). Flora of the Venezuelan Guayana 8: 497–847.

How to cite

Zappi, D. (2009). Neotropical Rubiaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Rubiaceae.htm.