Lasianthus is a genus of flowering plants in the family Rubiaceae. They are tropical subshrubs, shrubs, or rarely, small trees. They inhabit the understory of primary forests.
Lasianthus has about 300 species. The type species for the genus is Lasianthus cyanocarpus. In 2012, a revision of Lasianthus in Malesia described 131 species. Another 30 or so species grow elsewhere in tropical Asia. Most of these are described in Flora of ChinaHua Zhu and Charlotte M. Taylor. 2011. Lasianthus, pages 185-198. In: Wu Zhengyi, Peter H. Raven, and Hong Deyuan (editors). 1994 onward. Flora of China, vol. 19: Cucurbitaceae - Valerianaceae, with Annonaceae and Berberidaceae. Science Press: Beijing, China; and Missouri Botanical Garden Press: St. Louis, MO, USA. (vol. 19) (set). (See External links below). or in A Revised Handbook to the Flora of Ceylon.Colin E. Ridsdale. 1998. Rubiaceae, pages 141-343. In: Meliyasena D. Dassanayake and William D. Clayton (editors). A Revised Handbook to the Flora of Ceylon, vol. 12. (vol.12) (See External links below). 14 or 15 species are native to the Western Ghats of southwestern India, including the endemic Lasianthus agasthyamalayanus.Jagadeesan Raveendran, Sam Paul Mathew, Gangaprasad Appukuttannair, and Ettickal Sukumaran Santhosh Kumar Lasianthus agasthyamalayanus (Rubiaceae), a New Species from the Southern Western Ghats, Kerala, India," Annales Botanici Fennici 55(1–3), 87-91, (1 May 2018). https://doi.org/10.5735/085.055.0110 Fifteen speciesDavid J. Mabberley. 2008. Mabberley's Plant-Book third edition (2008). Cambridge University Press: UK. or perhaps as many as 20 speciesBernard Verdcourt. 1976. Lasianthus. pages 134-145. In: Rubiaceae (part 1). In: Roger M. Polhill (editor). Flora of Tropical East Africa. Agents for Oversea (sic) Governments and Administration. London, U.K. (See External links below). are known from tropical Africa. Two species (Lasianthus panamensis and Lasianthus lanceolatus),Elmar Robbrecht. 1982. "The identity of the Panamanian genus Dressleriopsis (Rubiaceae)". Annals of the Missouri Botanical Garden 69(2):427-429. or possibly three, are native to the neotropics. The Australian Ixora baileyana had at one time been placed in Lasianthus as Lasianthus graciliflorus.Laurie G. Adams, Diane M. Bridson, and Elmar Robbrecht. 1987. "The Identity of Lasianthus graciliflorus Bailey (Rubiaceae)". Kew Bulletin 42(1):209-214.
Dried specimens of Lasianthus often shed their flowers and fruit. For this reason, misidentification is common, even in herbaria.
Species , Plants of the World Online accepts the following 292 species:
Description Subshrubs, shrubs, or rarely, small trees. Leaves opposite, distichous. Stipules interpetiolar, usually persistent. Inflorescences axillary, usually sessile. Flowers small, white. Calyx with 3 to 6 teeth or lobes; persistent. Corolla with 4 to 6 lobes; throat usually villous. Stamens 4 to 6, inserted on corolla throat. Anthers dorsifixed. Stigma with lanceolate or linear lobes. Ovary multilocular. Ovules basal, erect, 1 per locule. Fruit a small drupe, usually blue. Pyrenes with thick walls.
History The generic name Lasianthus is derived from the Greek lasios, "shaggy, velvety, hairy", and anthos, "flower".Umberto Quattrocchi. 2000. CRC World Dictionary of Plant Names volume II. CRC Press: Boca Raton; New York; Washington, DC; USA. London, UK. (vol. II). (see External links below). The genus was named by William Jack in 1823.Lasianthus in International Plant Names Index. (see External links below).William Jack. !823. Transactions of the Linnean Society of London 14:125. (See External links below).
Some authors have recognized Dressleriopsis and Litosanthes as genera separate from Lasianthus. Dressleriopsis was sunk into Lasianthus in 1982.
Litosanthes was erected by Carl Ludwig Blume in 1823. It was synonymized under Lasianthus in 1992.Mohan G. Gagnopadhyay and T. Chakrabarty. 1992. "A note on the status of Litosanthes Bl. (Rubiaceae)". Journal of Economic and Taxonomic Botany 16(2):337-338. DNA sequence analysis has not resolved the question of whether Litosanthes is nested within Lasianthus or separate from it.
Affinities Lasianthus, Saldinia, and Trichostachys form the tribe Lasiantheae in the subfamily Rubioideae. Perama is related to this group and might be included within it. Lasiantheae was formerly thought to be close to Psychotria, but is now known to be a basal clade in Rubioideae. It is sister to the large clade containing Coussarea, Psychotria, Spermacoce, and many other genera.
Saprosma and Amaracarpus were traditionally thought to be close to Lasianthus. Saprosma is polyphyletic, with only part of it related to Lasianthus. Amaracarpus is close to Psychotria. The African genera Batopedina and Dirichletia have also been suggested as relatives of Lasianthus.
Taxonomy Only one molecular phylogenetic study has sampled more than a few species from the tribe Lasiantheae. In that study, 11 species of Lasianthus were sampled, but few relationships were resolved.
In 2012, a revision of the Malesian species divided Lasianthus into 3 sections, based on the following type species: L. section Stipulares (Lasianthus stipularis), L. section Lasianthus (Lasianthus cyanocarpus), and L. section Nudiflorae (Lasianthus blumeanus). They did not recognize L. section Pedunculatae (Lasianthus biermanii), which some previous authors had recognized. They considered it to be indistinguishable from L. section Lasianthus.
References
External links Lasianthus at Tropicos Lasianthus at GRIN taxonomy for plants