NYMPHAEACEAE (water lily family)
Plants
perennial, herbaceous aquatics, with extensive, branching rhizomes, rooting at
and between the usually closely spaced nodes and sometimes bearing tubers
(produced in autumn), often with lacticifers (latex canals), but the sap
generally clear or at least not milky. Leaves spirally alternate,
long-petiolate (sometimes short-petiolate in submerged leaves or in plants
stranded on mud), the petiole to 2 m or more, in some leaves reaching the water
surface or slightly emergent, sometimes with reddish or brownish streaks or
lines. Stipules sometimes produced, when present represented by often
relatively conspicuous, sheathing scales, these sometimes fused into a single
unit. Leaf blades attached at the base of a deep sinus (peltate elsewhere),
variously shaped, the margin entire but sometimes slightly undulate, usually
with a narrow, pale to yellowish or brownish differentiated band, the upper
surface flat (the margins rarely curled upward slightly), usually with a
noticeable scar at the petiolar attachment, glabrous, often somewhat shiny,
rarely reddish-tinged, the undersurface green or slightly to strongly reddish-
or purplish-tinged, also sometimes with small brown spots, glabrous or less
commonly short-hairy, the venation usually with a single pronounced midvein,
the secondary veins numerous, pinnate from the midvein or partially palmate
from the petiolar attachment, branched dichotomously 2 or more times above the
midpoint, connected by a network of finer crossveins. Inflorescences of
solitary flowers, these usually long-stalked directly from the nodes of the
rhizome, floating or short-emergent, hypogynous or perigynous (epigynous
elsewhere), perfect, actinomorphic. Calyces of 4–8(–14) free sepals, some or
all of these usually petaloid in Nuphar, variously shaped. Corollas of
numerous free petals, these spirally arranged and overlapping, large and showy
or (in Nuphar) inconspicuous and scalelike, variously colored, sometimes
grading into the stamens. Stamens numerous, arranged in a dense, overlapping spiral,
the innermost and/or outermost sometimes nonfunctional (staminodes), the
filament usually flattened, strap-shaped, and 3-nerved, the anther often not
sharply differentiated, mostly appearing more or less embedded along the sides
or upper surface of the apical portion of the filament, yellow, lacking a
differentiated terminal appendage. Pistil 1 per flower, of 5 to numerous fused
carpels, the superior or half-inferior (fully inferior elsewhere) ovary with 5
to numerous locules, constricted slightly at the tip below a flattened,
expanded, disc-shaped apex, this with a radial pattern of raised stigmatic
regions or deep lobes. Placentation diffuse (laminar), the numerous ovules
attached all over the partitions between locules. Fruits berrylike or sometimes
more or less capsular, usually somewhat spongy or leathery at maturity,
indehiscent, or irregularly dehiscent near the base with age. Seeds numerous,
narrowly to broadly ovoid, variously colored, sometimes (in Nymphaea)
with a membranous, saclike aril. Six genera, about 65 species, nearly
worldwide.
The genera Brasenia
and Cabomba form an easily distinguished group that is closely related
to, but well-separated from the Nymphaeaceae. Some authors have continued to
treat these two groups as a single family, Nymphaeaceae (Judd et al., 2008),
but many others treat Brasenia and Cabomba in the segregate
family Cabombaceae (Les et al., 1999), a practice followed in the present work.
Steyermark (1963) and many earlier authors also included the genus Nelumbo
in the traditional concept of Nymphaeaceae, but that genus has been shown to be
more closely related to a small group of families that includes the Platanaceae
(sycamores, plane trees). For more details see the treatment of the
Nelumbonaceae and Judd et al. (2008).