Rafflesiales

From Palaeos

The Rafflesiales is an order of highly-reduced tropical holoparasites. The most famous genus, Rafflesia, contains parasites of Tetrastigma (Vitaceae) vines that prodice the largest single flowers known, up to 1m in diameter and weighing up to 7kg (Barkman et al., 2004). These flowers are actually the only visible part of the host, with the remainder permanently enclosed within the host stem.

Molecular analysis of Rafflesia and Rhizanthes by Barkman et al. (2004) found them to be related to the order Malpighiales. However, another parasitic genus traditionally included in the Rafflesiales, Mitrastema, was found to be completely unrelated to Rafflesia and a member of the phylogenetically distant order Ericales. As such, it is possible that the Rafflesiales represents an assemblage of unrelated plants whose shared characteristics have arisen convergently as a result of their parasitic lifestyle. Until this possibility is investigated, I provisionally retain the remaining "Rafflesiales" with Rafflesia.

<==Rafflesiales [Rafflesianae]
   |--Hydnoraceae
   |    |--Hydnora
   |    `--Prosopanche
   |--Cytinaceae
   |    |--Cytinus
   |    `--Bdallophyton
   `--Rafflesiaceae
        |  i. s.: Richthofenia
        |         Brugmansia
        |         Scytanthus
        |--Apodanthoideae
        |    |--Apodanthes
        |    `--Pilostyles
        `--Rafflesioideae
             |--Rhizanthes zippelii
             |--Sapria
             `--Rafflesia
                  |--R. arnoldii
                  |--R. hasseltii
                  |--R. keithii
                  `--R. pricei

* Type species of genus indicated

References

Barkman, T. J., S.-H. Lim, K. M. Salleh & J. Nais. 2004. Mitochondrial DNA sequences reveal the photosynthetic relatives of Rafflesia, the world’s largest flower. Proceedings of the National Academy of Sciences of the USA 101 (3): 787-792.

Polunin, I. 1988. Plants and Flowers of Malaysia. Times Editions: Singapore.

Thorne, R. F. 2000. The classification and geography of the flowering plants: Dicotyledons of the class Angiospermae (subclasses Magnoliidae, Ranunculidae, Caryophyllidae, Dilleniidae, Rosidae, Asteridae, and Lamiidae). The Botanical Review 66: 441-647.

Yampolsky, C., & H. Yampolsky. 1922. Distribution of sex forms in the phanerogamic flora. Bibliotheca Genetica 3: 1-62.

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