Coutoubeinae

Schultesia guianensis, copyright Sébastien Sant.

Belongs within: Chironieae.

The coutoubeines
Published 17 November 2019

Members of the family Gentianaceae, the gentians, are for the greater part associated with cooler climes. Residents of areas subject to heavy snowfalls have often commented on the appearance of their showy flowers with warming weather in the spring. But not all subgroups of the gentians are so temperate: some, such as the Coutoubeinae, are inhabitants of the tropics.

Schultesia guianensis, copyright João de Deus Medeiros.

The Coutoubeinae are a group of about thirty known species divided between five genera found in Central and South America (Struwe et al. 2002). A single species, Schultesia stenophylla, is found in western Africa but, as it is also found in Brazil alongside related species, it can be reasonably presumed to be a recent immigrant to that region. Like most other members of the Gentianaceae, species of the Coutoubeinae are low herbs, often found growing in open habitats. With the exception of the genus Deianira, most lack a basal rosette of leaves. Flowers are usually white or pink, and are quadrimerous (with four corolla lobes) in the majority of species (one species, Schultesia pachyphylla, has blue pentamerous flowers; Guimarães et al. 2013). Perhaps the most characteristic feature of the group is that pollen is released in tetrads (clumps of four). I haven’t come across any specific comments on the functional significance (if any) of this feature in coutoubeines but it has been suggested that pollen clumping in plants may correlate with visits from pollinators being relatively uncommon (and getting a decent amount of pollen transported at a time becomes more important than increasing the chance of pollen being transported to multiple targets).

Coutoubea spicata, copyright Alex Popovkin.

The largest genus of coutoubeines is Schultesia, including about twenty species. Schultesia species are annual herbs with long-lanceolate leaves and tube-shaped, usually pink (occasionally yellow or blue) flowers with the calyx tube at least as long as the lanceolate corolla lobes. The species Xestaea lisianthoides, sometimes included in Schultesia, differs from Schultesia in the arrangement of stamens (inserted unevenly in the corolla rather than in the upper part of the tube) and the shape of the stigmatic lobes (oblong rather than rounded). Coutoubea species have white, salver-shaped flowers with triangular corolla lobes. Symphyllophyton caprifolium, a rare species restricted to southern Brazil, is a short-lived perennial with perfoliate leaves and yellow to cream salver-shaped flowers with the calyx tube shorter than the corolla lobes. Finally, Deianira includes suffrutescent herbs with a basal rosette of leaves and salver-shaped flowers with a short calyx tube.

Systematics of Coutoubeinae
<==CoutoubeinaeSK02
|--Xestaea Grisebach 1849SK02
| `--*X. lisianthoides [=Schultesia lisianthoides]SK02
|--+--Symphyllophyton Gilg 1898SK02
| | `--*S. caprifolioidesSK02
| `--Deianira von Chamisso & von Schlechtendal 1826SK02
| |--*D. erubescensSK02 [incl. Callopisma perfoliatumG39]
| |--D. cordifoliaSK02
| |--D. cyathifoliaSK02
| |--D. foliosaSK02
| |--D. nervosa [incl. Callopisma amplexifolium]G39
| `--D. pallescensSK02 [=Exacum pallescensG39, Dejanira erubescens β pallescensG39]
`--+--Coutoubea Aublet 1775SK02
| |--*C. spicataSK02 [incl. C. albaG39]
| |--C. densiflora [incl. Exacum spicatum, E. ternifolium, Coutoubea ternifolia]G39
| |--C. humilisBC02
| |--C. minor [=Exacum minus; incl. E. strictum]G39
| |--C. racemosa [incl. C. arenaria]G39
| |--C. ramosa [incl. C. purpurea]G39
| |--C. reflexaSK02
| `--C. volubilis [incl. Lisianthus scandens]G39
`--Schultesia von Martius 1826–1827SK02
|--*S. crenulifloraSK02 [incl. Sebaea brasiliensisG39]
|--S. angustifoliaSK02
|--S. apteraG39
|--S. australis Grisebach 1839G39
|--S. benthamianaSK02
|--S. brachyptera Cham. 1833 [incl. S. heterophylla Miq. 1847]L95
|--S. gracilisG39
|--S. guianensisSK02 [=Exacum guianenseG39]
| |--S. g. var. guianensisN02
| `--S. g. var. latifoliaN02
|--S. pohlianaSK02
|--S. stenophylla [incl. Exacum cubense, Erythraea jorullensis, Ex. purpureum]G39
| |--S. s. var. stenophyllaBC02
| `--S. s. va. latifoliaBC02
`--S. subcrenataSK02

*Type species of generic name indicated

References

[BC02] Bouman, F., L. Cobb, N. Devente, V. Goethals, P. J. M. Maas & E. Smets. 2002. The seeds of Gentianaceae. In: Struwe, L., & V. A. Albert (eds) Gentianaceae: Systematics and Natural History pp. 498–572. Cambridge University Press: Cambridge.

[G39] Grisebach, A. H. R. 1839. Genera et Species Gentianearum adjectis observationibus quibusdam phytogeographicis. J. G. Cotta: Stuttgardt.

Guimarães, E. F., V. C. Dalvi & A. A. Azevedo. 2013. Morphoanatomy of Schultesia pachyphylla (Gentianaceae): a discordant pattern in the genus. Botany 91: 830–839.

[L95] Liogier, H. A. 1995. Descriptive Flora of Puerto Rico and Adjacent Islands: Spermatophyta-Dicotyledoneae vol. 4. Melastomataceae to Lentibulariaceae. Editorial de la Universidad de Puerto Rico.

[N02] Nilsson, S. 2002. Gentianaceae: a review of palynology. In: Struwe, L., & V. A. Albert (eds) Gentianaceae: Systematics and Natural History pp. 377–497. Cambridge University Press: Cambridge.

[SK02] Struwe, L., J. W. Kadereit, J. Klackenberg, S. Nilsson, M. Thiv, K. B. von Hagen & V. A. Albert. 2002. Systematics, character evolution, and biogeography of Gentianaceae, including a new tribal and subtribal classification. In: Struwe, L., & V. A. Albert (eds) Gentianaceae: Systematics and Natural History pp. 21–309. Cambridge University Press: Cambridge.

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