62 genera/2500 spp.
worldwide, in temperate and boreal habitats; lianes (Clematis
spp.), small shrubs, but usually herbs, sometimes aquatic.
Flowers usually bisexual, insect-pollinated, usually actinomorphic (but see Aconitum, Delphinium); wind-pollinated in Thalictrum. Receptacle elongate, perianth spirally arranged; K(3-)5-8; C(0)few-many, often with basal nectaries; Amany, spirally arranged, centripetal; G1-several, rarely connate (i.e. apocarpous), with axile placentation. Ovaries each with several to many ovules, developing into follicles, achenes, berries (capsule in Nigella).
This kind of floral organization (see photo below right) was, in the mind of the late 19th c. American taxonomist, C. E. Bessey, reminiscent of the extinct, Mesozoic cycad-like Bennettitales1 from which Bessey believed the flowering plants arose. In these plants the reproductive structures consisted of cone-like strobili with spirally arranged bracts, microsporophylls, and megasporophylls. Bessey supposed that these organs became transformed into, respectively, the perianth, stamens, and pistils of flowering plants. Accordingly, the Ranunculales ("Ranales") were seen by Bessey as the most primitive modern plants, representative of ancestors from which all other flowering plants arose in three main lineages. The diagram of flowering plant relationships at the right, taken from the 1988 book by Arthur Cronquist, is a modern descendant of Bessey's ideas. It implies that the Magnoliopsida ("dicots") and Liliopsida (monocots) are both monophyletic groups, something that not quite 20 years later is no longer supported by the available evidence (see also the Angiosperm Phylogeny Website, and the APGIII tree that is depicted there).
Ontario native genera of Ranunculaceae (Morton and Venn 1990): Actaea, Anemone, Anemonella, Aquilegia, Caltha, Cimicifuga, Clematis, Coptis, Hepatica, Hydrastis, Isopyrum, Myosurus, Pulsatilla, Ranunculus, Thalictrum.
Photo: © G. D. Carr and the Botany Department, University of Hawaii
Judd et al. 1999, p. 230ff.
1. Rothwell et al. 2009.
The Flora North America treatment of the Ranunculaceae (Whittemore & Parfitt 1997) is available HERE:
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