Introduction to Centrospermae

V. Bhtrich

The Caryophyllales or Centrospermae (Eichler 1878) are a good, if not the best, example of a major natural group within the angiosperms. First recognized by Bartling (1830) as "Caryophyllinae", it is accepted at present in nearly the same circumscription as in Braun's treatment (1864; see Table 1). The most useful characters for the order known at that time were the so-called free-central placentation, the mostly campylotropous ovule (e.g., Hofmeister 1858), and the presence of perisperm (e.g., Schleiden and Vogel 1838; Endlicher and Unger 1843). When one compares the order as defined by Braun (1864) or Hallier (1912) with the circumscription given, for instance, by Takhtajan (1959), little progress seems to have been made. Since then, the investigation of sieve-element plastids, betalains, bound ferulic acid in unlignified cell walls, serology, and DNA-RNA hybridization, confirmed beyond reasonable doubt the correctness of the circumscription of the order with the inclusion of the Cactaceae and Didiereaceae, and the exclusion of the Bataceae, Gyrostemonaceae, Theligonaceae, Plumbaginaceae, and Polygonaceae. They also provided new and important characters for an understanding of phylogenetic relationships of the order and its subdivision. Yet taxonomic studies showed that several families in their traditional circumscription are paraphyletic or polyphyletic. Therefore, a completely new subdivision of the order at the present state of knowledge seems to be premature, and it is preferable to use the families mainly in their traditional circumscription while keeping in mind that their strict monophyly is sometimes dubious.

After the important findings in the 1960s and 1970s, the Centrospermae seemed to be the most thoroughly investigated order of the angiosperms. It was therefore not surprising that they were the subTable 1. System of the Centrospermae ("Caryophyllinae"). Braun (1864)

?1. Nyctaginaceae

  1. Chenopodiaceae
  2. Amaranthaceae
  3. Caryophyllaceae
  4. Phytolaccaceae
  5. Portulacaceae
  6. Aizoaceae
  7. Opuntiaceae ject of one of the first cladistic treatments of a major plant group (Rodman et al. 1984). However, this study failed to accomplish its intended objective of clarifying Centrospermae phylogeny (for a critique, see Levin 1985; Hershkovitz 1989), and it became apparent that the overall knowledge of the Centrospermae is still too incomplete to allow such a rigid approach. It thus remains questionable whether the results of a cladistic treatment of the Centrospermae at present are superior to a scheme of relationships based on a conventional systematic approach.

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