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(Last Modified On 2/7/2013)
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(Last Modified On 2/7/2013)
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Family
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NYMPHAEACEAE
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Contributor
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J. A. DUKE
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Description
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Partially or completely submerged rhizomatous aquatics, caulescent or acaules- cent, with laticiferous vessels, air spaces and scattered vascular bundles devoid of cambium and vessels, often with idioblasts. Leaves opposite or alternate, the submerged leaves often dissected, the floating leaves more often entire, long- petiolate, often peltate, the venation palmate, with frequent dichotomies or tri- chotomies, often reticulate. Flowers often large and showy, long-pedicellate, usually solitary, regular, hypogynous to perigynous or epigynous, cyclic to spiral, 3- to 5(-7)-merous. Sepals 3-5(-7), free or slightly connate basally, like or unlike the petals. Petals 3-many, free or slightly connate basally, often brightly colored, occasionally grading into the stamens. Stamens 3-many, the anthers sessile or borne on long, often basally dilated, filaments, entire or apiculate. Carpels 3-many, apocarpous or syncarpous, superior to inferior, with 1-many orthotropous to anatropous ovules attached to the inner wall or pendulous from the summit of the carpel. Fruit a nut, pod or berry, the mature carpels indehiscent, the seeds arillate or naked, smooth or echinate, albuminous or exalbuminous.
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Note
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A casual perusal of the above description discloses the heterogeneity of this family, a tropical and temperate group of about nine aquatic genera, several of them cultivated. Noting that the characters which hold the family together are largely a function of environmental adaptations while more fundamental char- acters are quite contrasting, (e.g., inferior vs. superior ovary, cyclic vs. whorled floral arrangement, albuminous vs. exalbuminous seeds, arillate vs. exarillate seeds), Li (in Am. Midl. Nat. 54: 33. 1955) has redistributed the members of Nymphaeaceae sensu lato among five families, two of which incur ordinal status as well. Although there is rno small amount of logic in Li's disposition, it seems best to retain the Nymphaeaceae sensu lato for the Flora of Panama, with only two indigenous genera.
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Key
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a. Leaves all entire or dentate; sepals, petals and carpels numerous; anthers in- trorse; carpels coalescent, the ovules numerous in each locule; fruit in- durate ...................... 1. NYMPHAEA aa. Some or all of the leaves finely dissected; sepals, petals and usually the carpels 3; anthers extrose; carpels remaining free, the ovules 1-3 in each carpel; fruit baccate ...................... 2. CABOMBA
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