Home / Anomalous_Items / Aquatic_Macrophytes / Emergent_Leaves / Ranunculus
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Name derivation:
‘Little frog’ – diminutive of Rana = frog (L.). Common names include ‘aquatic buttercup’, ‘water crowfoot’.
Classification:
Ranunculus Linnaeus; approximately 600 species descriptions are currently accepted taxonomically, including terrestrial as well as aquatic habitats (Subclades Batrachium ‘aquatics’ and Hecatonia ‘semiaquatics’); aquatic species are considered to be derived from terrestrial ancestors, as reviewed by Hörandl and Emadzade in their ‘pluralistic approach for classification’ that includes analysis of both molecular and morphological traits(2012). Order Ranunculales; Family Ranunculaceae Herbaceous dicot, includes many hybrids; ~40% of Ranunculus species are polyploids (Ibid.).
Morphology:
Heterophylly includes highly dissected submerged leaves 2 – 3 cm long, and more entire 3-5 lobed floating and emergent leaves. Leaf anatomical and morphological development includes temperature and submersion in water, and likely involves growth hormones (Bostrack and Millington 1962). the latter, especially the importance of ethylene and its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) has been confirmed and is reviewed by Samarakoon and Horton (1984). The authors experiments demonstrate increases in leaf petiole leaf with higher levels of ethylene in the range 0.01 to 1000 ml l-1 within one day. Such elongation can keep leaves emergent with rising water level. Flowers are 5-part and either yellow or white (species specific). Fruits are achenes (dry with one seed).
Similar genera:
Anenome and Isopyrum are treated as outgroups (Hörandl and Emadzade 2012.).
Habitat:
Freshwater, shallow marshes, streams and lakes. Provides food for ducks but is poisonous to many mammals until plants are dried.
References:
Bostrack, J.M. and W.F. Millington 1962. On the determination of leaf form in an aquatic heterophyllous species of Ranunculus. Bulletin of the Torrey Botanical Club 89(1):1-20. Hörandl, E, and K. Emadzade 2012. Evolutionary classification: A case study on the diverse plant genus Ranunculus L. (Ranunculaceae). Perspectives in Plant Ecology, Evolution and Systematics 14:301-324. Samarakoon, A.B., and R.F. Horton 1984. Petiole growth in Ranunculus sceleratus L.: Ethylene synthesis and submergence. Annals of Botany 54:263-270.