Gentianales (Coffees, Dogbanes, Gentians and Milkweeds)


The angiosperm order Gentianales includes the Apocynaceae (dogbanes and milkweeds), Gelsemiaceae, Gentianaceae (gentians), Loganiaceae (strychnine plants) and Rubiaceae (coffee and madder plants). They are found worldwide in most climates, but are most abundant in the tropics.

Keywords: botany; systematics; asteridae; classification; evolution

Figure 1.

Stem with opposite leaves and interpetiolar stipule (IS).

Figure 2.

Colleter, multicellular gland, in cross‐section, showing central glandular port and multicellular surface.

Figure 3.

Flowers of Gentianales. (a) Symbolanthus (Gentianaceae), with basally fused calyx and trumpet‐shaped fused corolla. (b) Cross‐section of typical Rubiaceae flower showing inferior ovary, calyx, corolla, and stamens inserted into corolla tube. (c) Cross‐section of typical Gentianaceae and Loganiaceae flower, showing superior ovary, otherwise the same as (b).

Figure 4.

Seed from Asclepias (Apocynaceae), showing tuft of hairs on one end.

Figure 5.

Flower (a) of Asclepias (Apocynaceae), showing intricately formed appendages on corolla, fused staminal parts around style and (b) magnified pollinia with ‘handles’ (called translator).

Figure 6.

Flower bud with contort corolla bud in Gentianaceae. Note calyx fused at the base and two leaves at the base of the flower.

Figure 7.

Synopsis of phylogenetic relationships in Gentianales. Characteristics for families and groups of families are noted.


Further Reading

Backlund M, Oxelman B and Bremer B (2000) Phylogenetic relationships within the Gentianales based on ndhF and rbcL sequences, with particular reference to the Loganiaceae. American Journal of Botany 87: 1029–1043.

Endress ME, Sennblad B, Nilsson S et al. (1996) A phylogenetic analysis of Apocynaceae s. str. and some related taxa in Gentianales: a multidisciplinary approach. Opera Botanica Belgica 7: 59–102.

Leeuwenberg AJM (ed.) (1980) Fam. Loganiaceae. Die natürlichen Pflanzenfamilien. vol. 28b(1). Berlin: Duncker and Humblot. [In English.]

Robbrecht E (1988) Tropical woody Rubiaceae. Opera Botanica Belgica 1: 1–271.

Struwe L and Albert VA (eds) (2002) Gentianaceae – Systematics and Natural History. Cambridge: Cambridge University Press.

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How to Cite close
Struwe, Lena(Jul 2002) Gentianales (Coffees, Dogbanes, Gentians and Milkweeds). In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0003732]