The ginger family
Zingiberaceae is the spice family. It supplies ginger, turmeric, cardamom and galangal from underground stems, and above ground it builds a flower whose showiest part is not a petal at all but a set of stamens that gave up being stamens.
around 50 genera
roughly 1,600 species
Tropical, centered on southern and southeastern Asia
Everything in this guide that belongs to Zingiberaceae
A ginger flower has a broad flared lip at the front, usually the brightest and most patterned part of the whole thing, sitting exactly where a landing platform ought to be. In an orchid, which does the same job, that lip is a petal. Here it is not.
This family took its stamens and repurposed them. Of the original ring, only one is left doing the actual work of making pollen. The rest have given that up entirely and turned into flat colored structures, and two of them have fused together edge to edge into the single broad lip you are looking at. The showiest organ in the flower is sterile male tissue pretending to be a petal.
Two families arriving at the same landing platform from opposite directions, one out of a petal and one out of stamens, is a good illustration of how pollinators shape flowers. The insect needs somewhere to stand and something to aim at. The plant supplies it from whatever parts it has spare.
The ginger in a kitchen is not a root. It is a rhizome, a horizontal stem that runs just under the soil surface, and it has all the features of a stem: buds, segments, and rings where scale leaves were attached. The true roots are the thin ones hanging off it, and nobody eats those.
The leafy shoot above ground is not really a stem either. It is a pseudostem, a tight column of rolled leaf sheaths wrapped around one another, which is the same construction a banana uses and no coincidence, since they are in the same order.
The flowers frequently ignore the leafy shoot altogether. In many gingers the inflorescence comes up on its own separate stalk directly from the rhizome, pushing out of the ground on its own some distance from the leaves, so the flower and the foliage can look like two unrelated plants growing side by side.
Ginger, turmeric, cardamom, galangal, grains of paradise and zedoary all come out of this family, and all but one of them from a rhizome. Turmeric is the odd case worth knowing: the plant grown for it is sterile, sets no seed at all, and does not exist in the wild. It has been carried and divided by hand for thousands of years, so every turmeric plant in cultivation is a piece of the same continuous organism.
Cardamom is the exception to the rhizome rule, since it is the seed pod that is used, and it is the most expensive spice in the world after saffron and vanilla. The reason is labor: the pods on a single plant ripen at different times and split open and spill if left too long, so the crop has to be hand picked over many separate passes across several weeks, each pass taking only what is ready.
Fresh ginger and dried ginger are not the same flavor and it is not simply a matter of strength. The compound that makes fresh ginger hot is one thing; drying converts a good deal of it into a related compound that is noticeably hotter and less bright, and cooking pushes the change further in a different direction again.
That is why gingerbread made with dried ground ginger tastes of something other than a fresh root, and why a recipe cannot swap one for the other and expect the same result. Fresh is sharper and more lemony; dried is deeper and burns further back in the throat.
The whole family runs on volatile oils held in the rhizome, which is also why these plants keep so well underground and so badly once cut, and why the ornamental members carry scent in their leaves as well as their flowers. Crush any part of a ginger and it smells like the family it belongs to.