Trees are just the things to hang a summer exhibition on. “Trees: Arboreal Selections” swings lazily, like a hammock, between historical paintings in Salander-O’Reilly’s inventory and its contemporary roster. Devoted as much to money as to painting, the show confirms sociologist Raymonde Moulin’s classic observation that the price paid for art has become the primary measure of its worth.

Nicholas Lancret’s “Le Menuet” (c. 1732) is a case in point. Lancret was an imitator of Watteau and an ambitious member of his workshop. After the older painter’s death, he became France’s most popular producer of fêtes galantes, Watteau’s signature subject. “Le Menuet” is one of them, an archetype of the contrived charm and opulence that repelled Jacques-Louis David, friend of Robespierre. Operatic emphasis on costume, setting — a cocoon of luxuriant foliage — and Arcadian artificiality made an overt appeal to the aristocracy in the twilight decades between the zenith of the French monarchy under Louis XIV (d. 1715) and its bloody end under the Jacobins.

Untraced since its last appearance on the market in 1914, “Le Menuet” was purchased by Lawrence Salander at Sotheby’s in January 2005 for $650,000 (according to ArtNet’s Paul Jeromack), above the pre-auction estimate of $300,000 to $500,000. Eighteen months later, the gallery has marked it up nearly 400% to $2,500,000.The asking price is a testament to how much the newly rich will pay for prestige and totems of association with — and ascendance over — the old aristocracies.

Robert De Niro Sr.(d.1993),provides a modern, reductive correlative to rococo languor. Stock opinion notwithstanding, his gestural notations epitomize lazy nonattendance in front of a subject. A lavish carved frame around “Winfield Street I, Bernal Heights” (1978), typical of his Hans-Hofmann–legacy product line, suggests the grand style. At $125,000, the tab brings us back to Ms. Moulin: “Higher prices attract buyers . . . chiefly because the buyer who is not a connoisseur sees the price of a painting as something to admire about it.”

Compare Lennart Anderson’s trio of landscape studies. Framed in his studio with simple wooden slats, these intelligent distillations of landscape motifs make no false claims for themse lves. While forms are highly generalized, tonal variation is a faithful expression of the light and air of a particular place. One small, untitled oil from 1976 surrounds a tree trunk with a medley of modulated greens. The vernal trunk is keyed to the color around it, anchoring the single depicted shape to its suggestive field.

Stanley Lewis is another painter resistant to shallow artifice. An esteemed teacher, his work is much admired by other painters. The three tree studies here mirror both his tactile, even sculptural, sensibility and his humility before the loveliness of mundane things. Drawing and painting are inseparable acts to Mr. Lewis; each obsessive brush stroke serves depiction. He works and reworks his surfaces until spatial depth becomes palpable. The most recent study, an untitled portrait of a single tree, builds on the pictorial possibilities of light glimpsed through myriad interstices of branch patterns.

Mr. Lewis’s rich surfaces find a complementary echo in the work of Christopher Bramham and Albert Kresch. Mr. Bramham, who lives and works in Cornwall, N.Y., and exhibits at Marlborough, approaches his motifs with the straightforward fidelity of the British landscape tradition. “Railway Embankment, Early Morning” (1993) uses a spray of white flowering bramble to lend light to a stilldark motif.

Mr. Kresch — like Mr. Lewis, a painter’s painter — is the most delicious of the contemporary artists here. Born in 1922 and also a student of Hofmann, he has just begun to gain deserved recognition. “Sky Parade” and the tiny “House by the Road” (2000) illustrate his expressive color and dry, encrusted images. Flakes of bone-dry color bestride each other; the surface builds by accretion like a coral reef. Neither of the two paintings here sufficiently represents the range of his vivacity, but they are enough to bring you back for more.

A little oil “Study of a Tree Trunk” (c. 1828) by John Constable, the nonpareil of British landscape painting, is tagged at the same price as the De Niro. In just this way does history bend to lend spurious prestige to a lesser modern bauble. On the same wall is “At the Ford” (c. early 1880’s) by Albert Ryder, a darling among forgers even in his lifetime. His high prices in old age plus the easily replicated murk of work already in disrepair encouraged fakery. The painting’s foreground maiden and her horse are barely discernible, sunk into the blackened soup resulting from Ryder’s unsound techniques. ($650,000 asked; bids wanted.)

Nearby is an untitled landscape panel painted last year by Bil Thibodeau. Prisoners of names and the cache attached to them will pay up for the Ryder blur. But if you care about what you actually see, Mr. Thibodeau’s liquid hand and darkling palette will serve you nicely for $1,900.

Hofmann’s students are much in evidence. Paul Resika’s “Olives” (1994–97), a paradisal confection in sky-dyed blue, keeps sufficient faith with its subject to stay honest. But if you love the distinctive, gnarled beauty of an olive tree’s branching habit, you might be disappointed that depiction surrenders so readily to painterly brio. Louisa Matthiosdottir’s undated woodland clip “Skowhegan” suffers from proximity to Alfred Maurer’s glorious “Landscape” (c. 1915). Her uninflected paint surface and stiff, parallel forms look like a schoolgirl exercise next to the shimmering iridescence of Maurer’s dancing, transparent brushwork and unshackled coloration.

Not to be missed is an early, broody landscape by Stuart Davis.”Landscape Blue” (c.1918) suffuses expressive drawing with a lazuline melancholy. Its non-imitative color and broad generalization of forms prefigures his later modernist achievement.

Until August 11 (20 E. 79th St., 212-879-6606). Prices: $1,900–$650,000.