The water lily family
Nymphaeaceae is one of the oldest branches of the flowering plant family tree still in business. It also contains a leaf strong enough to stand on and a flower that heats itself, changes color and locks its pollinators in for the night.
around five genera
roughly 70 species
Fresh water worldwide, from the tropics to the far north
Everything in this guide that belongs to Nymphaeaceae
Flowering plants are a single enormous group, and almost all of them sit on a few vast branches that spread late. A handful of small lineages split off close to the base, before that spreading happened, and have been going their own way ever since. The water lilies are one of them.
This is not the same as calling them primitive, which suggests something unfinished. They have had exactly as long to evolve as an orchid has. What it means is that they separated from everything else very early, so the features they share with other flowers are the ones that were already present at the beginning, and the rest they worked out alone.
It shows in the flower. The parts grade into one another rather than falling into clean categories, so the outer segments shade gradually from sepal into petal and the inner petals shade gradually into stamens, with intermediate organs at every step. There is no sharp line anywhere, because the sharp lines came later.
The giant water lily of the Amazon carries floating leaves that reach roughly ten feet across, with a turned up rim, and they will support the weight of a child spread over a board. That is not the leaf being thick. Underneath it is a radiating framework of massive ribs, cross braced between the spokes, carrying the load out to the edge exactly as an engineered floor does.
Joseph Paxton grew the plant in England in 1849, put his daughter on a leaf, and said outright that its underside gave him the structural idea he used for the Crystal Palace two years later. It is the most famous case in the history of building of a structure copied straight off a plant.
Every leaf in the family is rebuilt for water. The breathing pores are on the upper surface, which is the reverse of a normal land plant, since the underside is pressed against water. The stalk is full of long air channels running down to the rhizome in the mud, so the buried parts are supplied with oxygen from above, and the upper surface is waxed so heavily that rain beads and rolls straight off.
The giant water lily runs one of the most elaborate pollination routines known. On the first evening the flower opens white, warms itself to well above the surrounding air by burning its own reserves, and gives off a strong sweet scent. Scarab beetles find it by heat and smell, and settle into a warm, food stocked chamber. The flower then closes on them.
They are held all through the next day. That evening the flower reopens, the beetles are released covered in pollen, and the flower is no longer white. It has turned pink or purple and it has stopped producing heat and scent. The beetles, wanting warmth and supper again, fly to the nearest white flower, which by definition is one on its first night and receptive. The color change is a signal that this one is finished.
The flower carved and painted through every period of Egyptian art, held in the hand at banquets, opening from the mound at the creation of the world, is called the lotus in almost every book about it. It is not one. It is a water lily, the blue and the white species of the Nile, and the true lotus is an unrelated plant that arrived in Egypt much later.
The habit of calling it a lotus came through Greek and Latin writers and has proved impossible to shift, which is worth knowing when a customer asks for a lotus and means the flower on a tomb wall. The rest of the family is quieter: the yellow pond lilies of northern rivers, which smell faintly of alcohol and are nicknamed brandy bottle for the shape of the seed pod, and a small water lily of the arctic that flowers in melt water within a few weeks of the ice going.