Artist Ed Ruscha’s words are what you notice first. They often appear to be floating genie-like across the canvas or growing upward from the page, or in other instances they seem to be rushing at you front-on with the urgency of a message from the Emergency Broadcasting System.

But unlike TV warnings, these words and phrases are unlikely to cause alarm, though they may lead to amusement, disconcertion and even bewilderment.

And that’s OK, according to Ruscha, an unassuming gray-haired man dressed in a dark gray tweed jacket and faded black jeans.

“The idea of somebody misinterpreting one of my works is not an issue for me,” he says. “It’s open-ended.”

Which is a good thing for viewers of “Cotton Puffs, Q-tips, Smoke and Mirrors: The Drawings of Ed Ruscha,” a new exhibit that opened Sunday at the National Gallery of Art. For this first-ever museum retrospective of the 67-year-old part-pop expressionist, part-minimalist, part-conceptual artist’s drawings — slightly more than 90 of the some 2,200 he’s produced to date are included — offers no easy answers, though it is a lot of fun. It’s also rather ironic, says the gallery’s director, Earl Powell III, given that Ruscha dubbed one 1979 work, “I Dont Want No Retro Spective.”

The title of the exhibit, culled from an observation Ruscha made to the show’s curator, Margit Rowell, reflects both the implements used to make his dazzlingly modern visual concoctions, but also the legerdemain-like effect many of the works here project.

Organized chronologically, the exhibit traces the arc of Ruscha’s career, from his early days as a bright-eyed Oklahoma boy newly discovering the “narcotic attraction” of California’s palm trees as an art student in the 1950s-era City of Angels, through to his more recent unorthodox takes on the Los Angeles street grid.

In the early 1960s, Ruscha frequently traveled the legendary Route 66 between Oklahoma and California. Along the way, he stopped to photograph gas stations — images that ultimately ended up in the seminal book, “Twentysix Gasoline Stations.”

But while anonymous artifacts of modernity like the gas stations, and other photographic subjects of Ruscha’s, such as sleek L.A. apartment buildings, pop up in some of the earlier drawings, it is really words that dominate the show.

Ruscha readily admits to a fascination and “deep respect” for the odd — one would expect nothing less from the man who famously shingled a room for the 1970 Venice Biennale with 360 pieces of chocolate silkscreened paper (this year he’ll again represent the United States at the renowned annual international art exhibition) — and that obsession comes across in both the medium and the message.

Indeed, there is a quirky sensibility undergirding everything Ruscha does. In the search for a powdered pigment to create his images in the late 1960s, he tried dirt and when that didn’t stick, Ruscha picked up a spare can of gunpowder and went to work. Later, when he was looking for a change, he turned to more natural pigments like celery, rose petals and tobacco; one of the show’s more humorous offerings is a rectangular drawing of the word “Colorfast?” done in beet juice decades ago, the pigment of which has completely faded.

Some of his earlier word drawings themselves appear as abstractions: Several are depicted as if a roll of paper tape had unfolded in curlicues across the canvas. And depending on how you view these they can take on multiple lives of their own. It is not just the word “Lisp” or “City” staring out at you from oblique aerial angles and orientations, but some entirely new entity, perhaps. Glance quickly at the flowing cursive loops in some of these and the effect invokes the Arabic lettering on the Saudi Arabian flag.

Other later word drawings have a more billboard, cinematic quality — “dumb face-on word explorations,” he calls these — and are carried out free form in a standard block lettering or in another completely linear style, which Ruscha has whimsically dubbed “Boy Scout utility modern.”

For Ruscha, words are “excuses to make works.” Once a word or combination of words has captured his imagination, he says, “I think the only way to hammer that thing down is to make a drawing of it and then it’s official and then I can put it away from my line of thinking.

“I’m not trying to create a riddle,” he asserts.

The words for his images may appear to him in dreams (which, he says, give you the “real protein”), in a Frank Zappa song or in the ordinary encounters of daily life. For instance, the aphorism “Science Is Truth Found Out,” which Ruscha employs in an eponymously titled work from the late 1980s, comes from the entablature of a Hollywood high school.

Due in part to space constraints, the National Gallery exhibit has about 20 fewer works than the exhibit by the same name that opened at New York’s Whitney Museum of American Art last summer and at Los Angeles’ Museum of Contemporary Art in October. For instance, viewers won’t see any of Ruscha’s well-known mid-1970s “Miracle” drawings — depicting light bursting through cloud cover — or any of his now-somewhat dated (at least in their power to shock) “Sex” pastels (though they will be treated to a red, white and blue play on the word).

Still, there is something to be said for brevity. Just as there is something to be said for the absence of words, implied in Ruscha’s fuzzy silhouettes of a bison and a ship. In each of these, he includes what he terms “censor strips,” where “words might go.” Thus he raises the question: Were the strips meant to obfuscate a message, provoke thought, or maybe both?

“There’s always that little question out there,” Ruscha says of his works. “The unknown is still there.”

One thing you can be sure of, however, is when you have reached the end of the exhibit — the quartet of “The End” acrylics on the wall should clue you in.

“They come from the vertical scratches and pops and all those things that happened … at the very end of a movie,” Ruscha explains. “I always thought that was so beautiful.”

But like some of his organic pigments, Ruscha realizes these images may have a shelf life, too, at least when it comes to resonating with an audience. “Fifteen or 20 years from now there won’t be scratches on the film and people will look back and [they’ll] look at me and say, ‘What are these scratches?’”

“Cotton Puffs, Q-tips, Smoke and Mirrors: The Drawings of Ed Ruscha” runs through May 30 in the National Gallery of Art’s West Building. For more information, go to www.nga .gov.