The bitterness of gentian yellow
Angostura (and other) Bitters, Aperol (and presumably Campari), Avèze and many more astringent liqueurs get their characteristic bitterness from a macerated extract of the Gentian root. Gentian root was once used in beer but the easier-to-source hops soon took over that role.
Bitters and Aperol I like, and I tasted Avèze for the first time while staying with friends in Paris. As you do. And I liked it.
Inevitably there are other botanicals thrown in all these concoctions to both to add flavour and intrigue, but the southern European and western Asian Gentiana lutea, is a vital part of many bitter tasting drinks.
This species is also bitter enough to repel livestock, and the tall yellow flowers (as above, on the label) apparently stand out in European pastures on one of the few ungrazed plants.
An entry in Plant (the 'Ultimate visual reference to plants and flowers of the world', edited by Janet Marinelli) highlights the vulnerability of the species given most roots are extracted from wild plants, and often from plants yet to flower. As you would expect, the removal of the root kills the plant.
The makers of Avèze, in the mountains near Auvergne, a little to the west of Lyon, actually promote their wild sourcing of the Gentian. They, or at least their distributors, say theirs is 'the only French gentian liqueur flavored exclusively using wild yellow gentian collected from the historic national park of Volcans d’Auvergne'. I'm assuming they have some, sustainable, arrangement with the managers of this park.
The bitter chemical in the Gentian is gentiopicricide, an 'iridoid gylocoside'. Iriodoids, I read, are a class of chemicals that are almost always bitter. Gentiopicricide has been applied to various maladies, such as 'gastric ulcer, dyspepsia, and hypochlorhydria' but may also 'exacerbate conditions associated with gastrointestinal hyperactivity, such as duodenal ulcer, gastroesophageal reflux, and hyperchlorhydria'.
I expect the quantities of this bitter chemical in Avèze are low enough to not remedy or exacerbate any gastric issues you might have, although they might just stimulate your appetite. As would be the levels in the other bottles of gentian flavoured liqueur offered to me on that night.
Suze, around since the nineteenth century (Avèze was first concocted in 1928/1929, originally as Auvergne) but tarted up in this pink bottle, has been described as 'vegetal, like eating dandelion greens, but ... also ... citric tones, like pomelo and perfume-y citrus—not lemon or lime'.
Ambassadeur seems to be a more recent invention, perhaps in the 1960s. Lillet is made bitter through the addition of quinine, not gentian.
For no other reason than taste, I preferred, with ice, on the night, Avèze.
As to gentians more generally, we often think of them as blue-flowered, such as this lovely Gentiana angustifolia from the Rock Garden, at Kew Gardens, which I've featured before - but they do come in many colours, shapes and sizes. The tall, yellow-flowered Gentiana lutea, on the label of Avèze, to my knowledge I have not seen or photographed.