Phylogenetic Relationships

Most authors recognize a phylogenetic relationship between the Apiaceae and the Araliaceae (e.g., Takhtajan, 1980; Cronquist, 1981). Many of the diagnostic features of the Apiaceae are found individually in members of the Araliaceae, and it has been suggested that the Araliaceae were ancestral to the Apiaceae (Cronquist, 1981). Thorne (1973, 1983) broadened the concept of the Araliaceae to include the Apiaceae, although he subsequently returned to a more traditional treatment (Thorne, 1992).

Phytochemical data support the close relationship between the two families (Gershenzon and Mabry, 1983). They both possess similar essential oils, containing volatile monoterpenoids as well as other constituents; triterpene saponins with oleanene- and ursene-type saponins; polyacetylenes;

an unusual fatty acid, petroselinic acid; and caffeic acid esters; they have similar flavonoid patterns and are similar in their absence of proanthocyanidins and ellagic acid derivatives. Recent cladistic analyses of morphological (Judd et al., 1994) and molecular (Plunkett et al., 1996a, 1997) data further support the close relationship between the Apiaceae and Araliaceae.

There has been some debate over the relationship of the Apiaceae and Araliaceae with the family Cornaceae. Takhtajan (1980, 1997) has argued that the two families are difficult to separate based solely on morphological characters. Cronquist (1981), however, noted phytochemical differences between the two families, with the Cornaceae apparently distinct because of the production of iridoids, ellagitannins, and proanthocyanidins and because of the absence of the polyacetylenes, essential oils, and coumarins.

Dahlgren (1980) has emphasized a relationship with the family Asteraceae (Compositae) based on the presence of sesquiterpene lactones, polyacetylenes, coumarins, and triterpenes in both groups. Dahlgren also noted morphological, embryological, and palynological similarities. The relationship with the Asteraceae was not supported by Cronquist (1981), however, who argued that morphological differences between the two families are significant, despite the phytochemical similarities.

Recent molecular investigations (Downie and Katz-Downie 1996; Plunkett et al., 1996b; Downie et al., 1998) have indicated that subfamily Apioideae sensu Drude (1898), which includes Pimpinella, is monophyletic, but that lower level tribal classifications within the subfamily are not supported, because of homoplasies in the more traditionally used fruit characters.

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