Nuphar advena (Aiton) W.T. Aiton

Spatterdock

© SRTurner

Family - Nymphaeaceae

Habit - Perennial aquatic forb.

Stems - Submerged rhizomes relatively stout, sometimes somewhat flattened, light yellow, not producing tubers.

Leaves - Submerged or more commonly floating or emergent; the submerged (overwintering and juvenile) leaves membranous (the margins appearing undulate or crisped), short-petiolate; the floating and emergent leaves leathery and mostly long-petiolate. Leaf blades 6-40 cm long and wide, nearly circular to ovate or broadly elliptic-ovate, rounded at the tip, the bases deeply cordate, the lobes rounded at the tip, mostly bright green, the upper surface of emergent leaves usually shiny, the undersurface glabrous or occasionally sparsely short-hairy, the venation mostly pinnate. Petioles spongy.

	Emergent leaf, dorsal.
© SRTurner

	Emergent leaf, ventral.
© SRTurner

	Petiole cross section.
© SRTurner

Flowers - Flowers emergent or appearing floating, 1.8-4.5 cm in diameter when open, hypogynous, the stalk relatively stout, glabrous or occasionally sparsely hairy. Sepals 6, 1.0-2.3 cm long, elliptic to oblong-elliptic, broadly ovate or nearly circular, rounded to truncate or very shallowly notched at the tip, strongly concave, ascending to somewhat spreading and remaining cupped around the pistil at flowering, the outer 3 or 4 sepals smaller, green or reddish-tinged on one or both surfaces, the inner 3-5 sepals larger, green (occasionally reddish-tinged) toward the base and on the outer surface, yellow or sometimes reddish-tinged above the often green basal portion on the inner surface, more or less persistent at fruiting. Petals numerous, inconspicuous, reduced to relatively thick, oblong, scalelike organs positioned below and similar in size and shape to the stamens, shorter than the sepals. Stamens 3-9 mm long, mostly truncate at the tip. Ovary superior, the perianth and stamens attached at its base. Stigmatic disc 6-28 mm in diameter, circular, unlobed, with 8-24, raised, linear to narrowly oblong or narrowly lanceolate, stigmatic regions.

	Flower.
© SRTurner

	Sepals.
© SRTurner

© SRTurner

	Longitudinal section.
© SRTurner

Fruits - Capsular, 1.5-5.5 cm long, globose to ovoid, somewhat ribbed longitudinally, green or reddish-tinged, irregularly dehiscent around the basal portion with age. Seeds obovoid, 3-6 mm long, the surface smooth, green to brown

	Fruit.
© SRTurner

Flowering - May - October.

Habitat - Ponds, sloughs, stagnant portions of watercourses.

Origin - Native to the U.S.

Lookalikes - The leaves can be mistaken for those of Nymphaea odorata (water lily).

Other info. - In Missouri this species is found mostly in the southern half of the state. Its continental U.S. distribution is somewhat scattered across most of the eastern half of the country. When in flower this plant is easily recognized, though usually difficult to observe closely due to its aquatic habitat.

The taxonomy of Nuphar has been somewhat controversial. Missouri plants were formerly assigned to a subspecies of Nuphar lutea; however, according to molecular data, the Old World N. lutea complex is mostly absent from North America (the exception being N. microphylla, found mostly in the northeastern US). North American plants have subsequently been assigned to several different species and subspecies. Yatskievych's Flora of Missouri lists N. advena with two subspecies extant in the state: ssp. advena, which has yellow or green sepals and larger flowers and fruits, and the less common ssp. ozarkana, which has red or purple shading on the sepal exteriors and smaller flowers and fruits.

Pollination in spatterdock apparently occurs via an assortment of flies, bees, and beetles which reflects the local abundance of these insects. Flowers are functionally pistillate on the first day, when they open only slightly to expose the stigmatic disk. The flowers close in the evening (often trapping beetles inside) and then open more fully on a few subsequent days, during which they are functionally staminate. The seeds of spatterdock are edible and can be ground into flour. The root is also edible but sometimes bitter. The fruits of this species and the related Nelumbo lutea have been used in dried flower arrangements.

Photographs taken at Busch Wildlife Area, St. Charles County, MO, 6-29-2012, and at Noblett Lake, Douglas County, MO, 6-2-2017 (SRTurner).