Home / Anomalous_Items / Aquatic_Macrophytes / Floating_Leaves / Brasenia
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Name derivation:
Common name – ‘water shield’
Classification:
Brasenia Schreb.; at least 7 species are recognized (Fassett 1953). Order Nympheales; Family Cabombaceae Dicot
Morphology:
Suybmerged leaves are highly dissected and reduced to an epidermal layer covering branched fascular bundles. At the time of flowering, floating leaves 6-12 cm long and 4-6 cm wide, with an entire outline, either oval or narrow and forked, help support emergent flowers for aerial pollination (Williamson and Schneider 1993). Numerous mucilage-secreting trichomes develop on the lower epidermal cells on the underside of the leaves. Flowers are perfect and trimerous (3 sepals, 3 petals, 6 stamens) and insect pollinated at least in C. caroliniana (Schneider and Jeter 1982). Turions (winter buds) are condensed apical organs with a thick reddish stem, dwarf leaves with thick petioles, and a coat of mucilage, are produced in early Fall. The turions abscise from the parent plant, sink to the sediments, and germinate the following Spring (Williamson and Schneider 1993).
Similar genera:
Cabomba has a similar flower development, especially in the initiation of the carpel based on SEM analysis (Endress 2005). The structure of the floaing leaves is also similar, including trichomes that secrete mucilage on the underside.
Habitat:
Freshwater in the tropics and subtropics of the ‘new world’.
References:
Endress, P.K. 2005 Carpels in Brasenia (Cabombaceae) are completely ascidiate despite a long stigmatic crest. Annals of Botany 96:209-215. Fassett, N.C. 1953. A monograph of Cabomba. Castanea 13:116-128. Schneider, E.L., and J.M. Jeter 1982. Morphological studies of the Nymphaeaceae. XII. The floral biology of Cabomba caroliniana. Williamson, P.S., and E.L Schneider 1993. Cabombaceae. In: Kubitzki, K., J.G. Rohwer, and V. Bittrich (Eds.) The families and genera of vascular plants, Vol. 2:157-161,