Italy is the most vertically oriented wine-producing country in the world. From the northern tips of Alto Adige and Valle d’Aosta to the heel of the boot in Puglia and Sicily’s lower corners, runs a taller spectrum of diverse wine regions than anywhere else. Chile and Argentina come close in kilometers, but the relative immaturity of those nations’ wine cultures and relative sameness of their climates and geology put them behind Italy.

The geographic length of a nation is not a much cited influence in discussions of wine, but it’s crucial to understanding what truly accounts for why a wine produced in one spot on Earth is different from others. Wine is a lens of soil, climate and culture. Nothing affects those factors more than their orientation to the equator.

It’s why pinot grigio from Friuli is refreshing and aromatic while pinot grigio from Sicily is an abomination; why Valtellina nebbiolo is so haunting but Tuscan (or French) nebbiolo doesn’t exist. It’s also why I, like many others, hardly consider “Italy” a single country, but instead a collection of dozens of states jammed together by political factors during the 19th century, which culminated in the country’s 1861 unification.

Luckily, the more than 1,000 (or 500 or 2,000, depending on which ampelographer you trust) extant native Italian grape varieties growing in hundreds of denominations have not been similarly compressed into one ill-fitting moniker.

I’m guessing the multiplicity of vineyard latitudes is the primary reason I have (unintentionally) focused more of my wine writing on Italy than anywhere else. There’s just more variety – of grapes, soils and microclimates – and therefore more mystery in which to lose myself. Against which, though, since the mystery of mysteries is that the mystery makes a hidden sense, a certain logical correlation starts to emerge: Wines from the north generally, taste cooler, more etched, more aromatically intense. Wines from the south swagger more, are fruitier and riper, and more generous.

And in the center lie … something else. The reds – Tuscan to Abruzzi – are much loved, are indeed many wine enthusiasts’ first and last love in Italian wine: succulent, spicy, hearty, warming, as in Brunello and Montepulciano.

It’s the white wines of central Italy, though, that I’ve lately come to appreciate anew. While these wines are not unknown in this country, especially to people who have traveled there, they play second fiddle to both their red counterparts and the great whites of the north. The number of names, collectively as spellbinding (or confusing) to us as the varietals of Greece or Portugal, is dizzying: vernaccia, verdicchio, vermentino, grechetto, pecorino, passerina and many, many more.

Years from now, if I remain dogged, I will be able to identify the particular attributes of each of these respective grapes. For now, I treat them as a staff of docents at a well-run museum: individuals, yes, but with a collective aim to expose the aesthetic heritage their museum was established to support. The white wine varietals of central Italy have a similarly collectivist orientation: to exalt a coherent geographical character.

My comprehension of this character is intuitive, hard to put into words, I-know-it-when-I-see-it. It’s the weight of any wine that first registers with me, and the weight of a true central Italian white wine is, well it’s central: sturdy but not loose, almost fatty the way a nicely marbled piece of meat is, a gravelly note in its voice and a calloused thickness to its handshake.

As for taste, I could twist myself in knots compiling adjectives, but what it comes down to is bitterness. That is the underlying force in the great white wines of central Italy. The underlying force of northern Italian whites is acidity (refreshing, electrified, high-toned); in southern whites it’s sweetness (ripe, soothing, satisfying).

From a public-relations perspective this is unfortunate, since the connotations of bitterness are decidedly less inviting than acidity or sweetness.

Most wine people who pick up on that component in a wine are (legitimately) afraid it won’t translate well, so they tend to employ euphemisms or evasions in describing it: almond skin, black licorice, tar, thyme. I’d rather just remind myself that bitterness is sensed on the tongue for a reason, just as sweetness, acidity, saltiness and savoriness are there for reasons. Sometimes we know the reasons, sometimes we don’t.

Bitterness is crucial, interesting, balancing; it adds to a wine’s complexity and elicits the individuality of its other aspects.

There are surely chemical, geological, perhaps climatological causes of the thrilling bitterness in white wines from Umbria, the Marche, Tuscany. I hope a doctoral student somewhere is working on this. Me, I just enjoy drinking the wines and continuing to discover the deeper connections between place and product.

Here are a few standouts, all of them vinified only in stainless steel: distinctive wines from the fulcrum of an infinitely diverse “country.”

• La Monacesca Verdicchio di Matelica 2014, $22. Most people familiar with whites of the Marche know Verdicchio di Castelli di Jesi, from the coast, producing relatively fruity, easygoing wines in distinctive hourglass-shaped bottles. Matelica, the smaller, more mountainous region inland, produces wines of far more substance and structure, capable of surprisingly long aging. Verdicchio has been genetically linked to garganega, the noble white grape of Soave. This makes sense given Soave’s well-known bitter-almond and lemon-pith character, which Verdicchio di Matelica carries as well. But that’s along with a flinty trait too, and La Monacesca even presents the slate-touched, kerosene-like aspect (see how many permutations of bitter there are?!) of steep-slope dry German riesling. A really extraordinary wine, for your table and cellar.

• La Spinetta Toscana Vermentino 2014, $20. This wine is like an admirable marriage, where two distinct personalities manage to simultaneously converge and retain individuality. How can a wine be both intense and delicate? How can its dryness resemble the crunch of a rye cracker while its fruit suggests ripe pink grapefruit? How can elegance pack such a punch? The vermentino grapes are organically grown and biodynamically farmed, by a modernist winemaking legend of both Tuscany and Piemonte.

• Arnaldo-Caprai ‘Grecante’ Grechetto 2013, $19. Moving east to Italy’s geographic center in Umbria, where the majority of grechetto is grown, we find this bitter marvel from a winery best known for its severe, long-aging (and themselves quite alluringly bitter) red wines from the sagrantino grape. The ‘Grecante’ is a languid and nutty white, chamomile-tinged and fennel-flecked, from the Colli Martani zone ordinarily considered the most favorable hills for the varietal to grow. The wine’s fruit is subtle; complex stone and seed aspects predominate.

• Argillae Orvieto 2014, $14. The only blend in this small selection, the ubiquitous trebbiano combined with grechetto, malvasia di candia, chardonnay and sauvignon blanc. Ordinarily I find such kitchen-sink mélanges of indigenous and “international” varietals too indistinct to be illustrative. But in this Umbrian wine, they express the essence of their home, in refined subcategories of bitterness: woodsmoke, blood orange, the wax in honeycomb. The wine’s assertive sting pierces its waxy fullness, as if it’s not exactly out to please anyone but ends up pleasing.

Joe Appel is the wine buyer at Rosemont Market. He can be contacted at:

soulofwine.appel@gmail.com