The violet and pansy genus
Viola is the genus behind three things a nursery sells under three different names, and the difference between them is a real one that catalogs rarely explain. It also contains one of the most chemically remarkable groups of proteins found in any plant.
roughly 600 species
Worldwide in temperate regions, with many species in the Andes
All three words point at this one genus and they are not interchangeable, whatever a garden center label suggests.
A pansy is a large flowered garden hybrid, bred up from a handful of European species over the last two centuries, carrying the biggest blooms in the genus and usually a dark central blotch. A viola, in the trade sense, is the smaller flowered kind: fewer inches across, many more flowers per plant, tougher in bad weather and far longer in flower. A violet is a wild or near wild species, smaller again, and the one that carries real scent.
The practical version is a straight trade off. Bigger flowers mean fewer of them and a plant that suffers in wind and heavy rain; smaller flowers mean a plant that carries on flowering when the pansies beside it have been flattened. Anybody choosing for a container in an exposed spot wants the second, and is usually sold the first because it looks better in the tray.
The garden pansy is one of the few ornamental plants whose invention can be dated and more or less credited. It came out of England in the early nineteenth century, from a small number of people crossing wild European violas at the same time, and it took about twenty years to go from a scattering of small wildflowers to something recognizable as a modern pansy.
The blotch arrived partway through as a chance seedling. Before it, the flowers carried only fine radiating lines; the dark solid mark that reads as a face turned up unbidden in somebody's seedling bed around 1830 and was immediately bred for, because it is what made the flower a curiosity rather than a wildflower.
It is worth knowing what those lines and blotches actually are, since they predate the breeding. They are nectar guides, converging on the throat of the flower where the reward is, and under ultraviolet light they are far stronger than they appear to us. The face was a pollination signal long before it was a selling point.
The wild European species that everything else descends from has collected more common names than almost any other plant in the language, and the list is a decent index of how much people liked it: heartsease, love-in-idleness, johnny-jump-up, three-faces-under-a-hood, tickle-my-fancy, and a good many more.
The love names are not decorative. The plant had a long reputation as an ingredient in love charms, which is why Shakespeare hands it to Oberon in A Midsummer Night's Dream: the juice of love-in-idleness, dropped on sleeping eyelids, makes the sleeper dote on the first creature they see. The whole plot turns on this genus.
Heartsease points at the other use. It was a standard herbal remedy for skin complaints and for chest conditions, and it is still sold as a dried herb for that, which is a long career for a plant most people now buy in a tray of six.
The genuinely extraordinary thing about this genus was not discovered until recently. Violas produce a family of small proteins whose backbone is joined head to tail into a closed loop, with the whole structure pinned together internally by additional bonds.
Having no loose ends makes them almost indestructible by the standards of proteins. They survive boiling, they survive the digestive enzymes that break ordinary proteins apart, and they hold their shape in conditions that would destroy almost anything comparable. The plant makes them as a defense against insects and disease.
That stability is why they are of interest well outside botany. Most protein based drugs cannot be swallowed, because the gut destroys them before they do anything, and a naturally occurring scaffold that survives the same journey is a promising thing to hang a drug on. The work is a long way from finished, and it started with somebody noticing that a tea made from a viola still worked after being boiled.
