Spring and summer provide us with some of the headiest and most ephemeral experiences in the garden. While describing the suddenness and intensity with which our Yoshino cherry tree blossomed a full, feathery white and then, like snowfall, shed its petals in the afternoon breeze, a friend reminded me of Bonnard’s paintings of flowering trees, suggesting that in Bonnard, no less so than in spring’s fleeting blossoms, we are witnessing “nature’s ecstasy.” The phrase “nature’s ecstasy” came to mind at Lennon, Weinberg’s gorgeous hothouse of a show, “Joan Mitchell: Paintings and Pastels 1973-1983,” a concentrated gathering of nearly 30 mostly small works on paper and canvas.

More than any other painter of the New York School, Mitchell (1925-92) immerses us in nature. She took her cues initially from the calligraphic brush handling of de Kooning, Guston, and Pollock, but ultimately she gave us an oeuvre that, among the Abstract Expressionists, is the most rigorously poetic. Her paintings begin with the premise that each work should be a living, breathing totality. Like the best calligraphers, Mitchell understands that her marks must add up to an animal whole — we must feel bone, tendon, and muscle, the rhythms of breathing, the fluidity of blood, and an inner spirit. Working with the metaphor of the landscape, however, she also imbues her pictures with the singular fullness of a tree or a flower or a field or a storm.

Mitchell is an expressionist, a sensualist, and a romantic, but she is also among the most discerning and pragmatic of New York School painters. Her best pictures, filled with thousands of singular bold strokes, combine into totalities that feel completely natural and self-sufficient — as if, rather than enforcing her own artistic vision, she were bringing us visions she had uncovered or had found.

To stand before Mitchell’s large, great symphonic works, especially the diptychs, triptychs, and quadriptychs that spread 20 or more feet across gallery walls, is to be enveloped in a jungle of sensations. Mitchell brings to her work the tingling, color-to-color rub and vibration — a synesthetic, no less than visceral or visual, impression — experienced in Titian, Renoir, Rothko, and Bonnard. She is a poet who distills, conflates, and transforms the world. Sometimes, as in the larger works, she buries us deep within the earth or throws us into the furnace; at other times, as in the small-scale pictures at Lennon, Weinberg, she brings us nature in the palm of her hand.

In these small works, Mitchell gives us heightened sensations of nature — haikus or chamber works as opposed to symphonies. In doing so, she puts our faces in the grass, rubs earth against our skin, bruises and cuts us, and brings us close to the bone. Many of these oils and pastels have the brutal freshness of just-cut flowers, or feel like pieces of cloud or rain or grass or sky.

Only one medium-to-large-scale canvas is on view at Lennon, Weinberg. “Buckwheat” (1982), at just more than 7 feet high and 6 feet wide, holds the end wall in a shrine-like alcove. An abstract homage to van Gogh’s wheat fields — but with Impressionist touches relating to Monet’s tangles and to Bonnard’s heat — “Buckwheat” is a shimmering, bustling flurry of golds and blues. It is an airy yet densely woven stratum — at times infernal and at other times watery and jewel-like — in which buoyant layers of wheat and sky, or fire and ice, mix and merge, rise out of or push in front of one another.

The decade represented by this exhibition, during which Mitchell was living in the French countryside, is not her best (I prefer the earlier and later works to those of the 1970s); but that criticism applies mostly to the large-scale canvases in which Mitchell attempts to wed the rectangles of Hans Hofmann (her former teacher) with her own physical calligraphy. Lennon, Weinberg’s show, however, which is a gathering of calligraphic and geometric fragments, works beautifully.

Some snow-scene pictures, such as the long oil on canvas, the triptych “Returned (Canada Series)” (1975), and the charcoal and Conté crayon drawings, all in brick-reds, blacks, whites, and grays, are abrupt, cold, blunt, and raw — registering like stubbed toes and skinned knees. Their rectangles punch with Rothkoesque authority, and those forms, along with the purplish, smoky grays and stucco-rough whites, linger tentatively, dangerously against the dried-blood-reds smeared on the page.

Some works in the show include typed poetry surrounded by and intermingling with Mitchell’s painting. In “Sunset (James Schuyler)” (1975), the text hangs in a vaporous gray-white field against an aquatic bluish mist, which is fed by a dense, dark tangle that resembles bonfire and rainbow. The painting is satisfyingly thin, wafting like a spring breeze, its forms and colors evocative of Schuyler’s text.

Other works in the show are autumnal in hue or fragrant with summer heat. “Pour Patou” (1976) has the muddy, rhythmic pulse of a hard rain. “Chiendent” (1978), more stem than flower, is violent and melancholy. “Untitled” (1977), a vertical oil made of daubed footprints of cool blue-violets and mossy greens, suggests the shaded canopy of a forest and, with its resemblance to stained glass, the hallowed light of a cathedral.

Three pastels and one painting in the show are from the series titled “Tilleuls” (“tilleul” is French for “linden tree”), a group of works named for a mature linden that crowned the terrace of Mitchell’s home overlooking the Seine in the French countryside. These paintings are concentrated and violent upsurges. Their linear tangles and touches of color suggest root, stem, sky, branch, clump, and leaf. They press forward as much as they shoot upward. And their biting lines scratch satisfyingly, like rubbing your back against the bark of a tree. These pictures, homages to the linden, do not look like trees, but that takes nothing away from their “treeness.” In her catalog essay for the show, Jill Weinberg Adams reminds us that Mitchell would not mind if one of her abstract paintings of a tree “‘looked exactly like a tree, as long as she ‘felt’ that tree.” Like those of Bonnard, Mitchell’s pictures evoke nature’s essences and transformations — from the formative to the gestational to the ecstatic. This exhibition allows us to “feel” nature, as Mitchell did, from the inside out.

Until June 21 (514 W. 25th St., between Tenth and Eleventh avenues, 212-929-3265).