I like fruit and nuts as much as anyone. But I can’t say I spend much time thinking about them.

In art, I am a bit of a sucker for a lemon painted by Zurbarán or an orange by Manet, and I don’t mind coming across the occasional bunch of bananas. (They crop up intriguingly in paintings by Giorgio de Chirico.) But apart from the fact that I occasionally dream about poached pears dripping in chocolate sauce, my reveries are fairly fruit-free.

Why, then, can’t I stop picking up and poring over “An Illustrated Catalog of American Fruits and Nuts,” a book that seems to have followed me around the house for more than a month now? One reason is that it’s so ridiculously beautiful.

Published by Atelier Editions in Los Angeles, it has an orange cover with handsome black typography. It has a fascinating introduction, a good index and glossary; it even smells nice.

But the best thing about it, undoubtedly, is the pictures. They’re pictures of fruit. And nuts. Made by hand. In watercolor. Hundreds of them have been selected from more than 7,500 paintings, drawings and lithographs from the Agriculture Department’s Pomological Watercolor Collection. (Pomology is the branch of agriculture focused on fruit.) Made between 1886 and 1942, the illustrations were commissioned from artists, the majority of them women, by the Division of Pomology, which wanted to create a national register of fruits.

And oh my goodness! They’re beautiful.

You need accurate color to catalogue fruit, which is why watercolor, rather than photography, became the preferred medium for systematically recording hundreds of varieties of cultivated fruits, or “cultivars.” A lot was at stake. “In the 19th century, healthy orchards and fruit groves were viewed as crucial to national prosperity,” Adam Leith Gollner, the Canadian musician and author of “The Fruit Hunters,” explains in his introduction. (The book also contains a short essay by London-based writer Jacqueline Landy and excerpts from previously published books by New Yorker contributor John McPhee and author Michael Pollan.)

Most fruit plants can be hybridized. As a result, all across 19th- and early-20th-century America, people were enthusiastically creating new varieties of fruit, and the USDA’s Division of Pomology was trying to keep track. At the same time, cultivars produced in the United States were being complemented by a boom in discoveries of fruit originally grown overseas. (Fascinating fact, which I learned from Gollner’s introduction: “The greatest diversity in any given fruit species is always found in the place where it originated.”)

Thus, the book contains illustrations of an extraordinary range of apples, which alone make up more than half of the images in the USDA’s holdings, as well as plums, peaches, papayas, persimmons, pineapples and pomegranates, not to mention walnuts, cashews, pecans, macadamias and almonds.

But there are also illustrations of fruits I’ve never heard of: chayote, sweetsop, cherimoya, sapodilla, passiflora and mammee apple.

On a technical level, the pictures are virtuosic. What I especially like is that, despite the scientific approach, aspects of personal style sneak into each illustration. Sometimes the artist focuses exclusively on the shape and color of the fruit itself, which can produce striking results. For instance, two vertical rows of bright red Coletto plums by an unknown artist in 1888 have an intensely abstract aura.

Other artists choose to include stems, leaves and branches. R.C. Steadman’s depiction of the slow-growing Damson plum, for instance, shows a cluster of around a dozen plums growing on a branch that descends from the top of the page, with at least 40 green leaves, some of them spilling over the page’s elegant geometrical borders. The image pops; you feel you could reach out and pick from it.

Certain artists made more illustrations than others: James Marion Shull, who specialized in depictions of infected fruit, painted more than 750. (One picture of a mold-covered lemon is particularly unappetizing.) Deborah Griscom Passmore painted one-fifth of the entire collection — more than 1,500 illustrations. She was so fastidious about getting the colors right that she was known to apply up to 100 color washes. Amanda Almira Newton, meanwhile, painted more than 1,200 of the collection’s watercolors. (She also made wax models of 300 fruit specimens.) Newton was known for depicting a whole fruit alongside the same fruit cut in half, to give an idea of the inside.

“Looking at the artworks in this book,” Gollner writes, “is the visual equivalent of tasting the incredible diversity of fruit grown at these clonal germplasm repositories.” He is referring to the U.S. National Plant Germplasm System, which preserves gene banks and germ plasm (genetic material or tissue that can be used to grow new plants) in locations across the United States. These seed vaults, Gollner writes, are “the country’s primary agricultural insurance” and part of the same project of documentation, classification and preservation to which the watercolors belong.

Indeed, quaint as they may seem, these exquisite watercolors have not outlived their usefulness. “There are still taxonomists,” according to Gollner, “who refer to the paintings in their efforts to unravel the past and contextualize modern-day science.”

For those of us who are not taxonomists, what stands out in this exquisite volume is the extraordinary diversity to which the illustrations attest. You probably won’t find Arkansas black apples, Coloway mulberries or Belle Angevine pears in your local supermarket. But it’s oddly reassuring, and obscurely enlivening, to know they exist.

“Diversity” has become a cant word in our culture. You hear it deployed in corporate colloquies, political speeches and school prospectuses as if it were a magic wand. It is used most often in the context of identity politics, but — as with so many balms peddled by quacks — it has migrated to other spheres of life and its meaning is usually left deliberately vague.

In truth, the most powerful forces in our culture are driving us away from diversity (in its broadest sense) and toward a homogeneity that is felt most catastrophically in the environment but also in the media, in our schools and universities, when we travel and when we shop for food.

So to be reminded, as this book does, of the astonishing diversity to be found in a sphere that uniquely combines nature and culture is uplifting. Long live the Fraud plum, the Golden Gate strawberry, the Memory grape, the Chinese Shaddock pummelo, the Wagner avocado, the Paradise banana, the Dancy tangerine and the Lisbon lime. Let their irregular shapes, their unique aromas, their blushing colors and their gorgeous names remind us of all that we stand to lose if we don’t value precisely what is strange, singular, foreclosed upon and factored out.