In honor of the centennial of Winslow Homer’s death, the Portland Museum of Art is showing 20 watercolors, oils and a variety of early graphics done by the artist considered one of the foremost painters in 19th century America.

Second-floor gallery walls painted a deep plum showcase the stark beauty of works by this preeminent American landscape painter and printmaker who lived from 1836 to 1910.

Some paintings in the “Winslow Homer and the Poetics of Place” exhibit are considered national treasures.

“Homer is the quintessential artist of Maine and considered one of America’s greatest painters,” said Thomas Denenberg, PMA’s deputy director and chief curator.

“Fine art always remains relevant. Homer’s focus on the environment is timeless. One of the ways we understand American history is through the lens of Winslow Homer,” Denenberg said.

Homer lived during a time when the United States developed from a young country of small towns into a modern industrial nation.

“Throughout his lengthy career as a graphic artist, genre painter and chronicler of the rugged Maine coast, Homer provided the nation with images that helped create a sense of place in an era of rapid change and growth,” according to the PMA.

At age 18, Homer showed great talent as a draftsman and began a three-year apprenticeship with lithographer J.H. Bufford. Printmaking with fine lines influenced his early work.

During the Civil War period, he worked as an illustrator for Harper’s Weekly, an early newspaper. About 250 wood engravings, mostly reproductions that appeared in Harper’s Weekly, can be viewed via a digitization and online exhibit. Museum visitors are able to zoom in on details in each work, and 20 works contain embedded text balloons that provide additional information.

A beautiful wood engraving from Harper’s Weekly titled “Noon Recess” depicts a schoolteacher sitting with a small boy who has been asked to stay inside at recess. One can see Homer’s initials on the blackboard behind the boy. This poignant illustration of a youth is charming and shows a dash of visual humor.

In stark contrast is Homer’s famous “Sharp Shooter” painting, his first work in oil, done in 1862, depicting a Union sharpshooter up in a tree and taking aim at an enemy soldier. (This and some other watercolors on view have rarely been seen due to their fragility and sensitivity to light.)

After the Civil War, Homer began to paint scenes of rural America, activities of everyday life and villages overlooking the sea. He traveled to Europe, where he painted English fishing villages. Upon his return to America in 1875, he traveled to the Adirondacks, where he joined a hunting club, and to Gloucester, Mass., where he painted harbor scenes.

“Boy in Boatyard,” a watercolor and gouache, is a sensitive work in the exhibit from that period. It is a work of subtle colors and unique perspective.

Another wonderful watercolor in the exhibit is “Girl Seated on Hillside Overlooking the Water.” This pensive work evokes a mystical quality, reflecting both the beauty of nature and the innocence of childhood.

A marvelous work is a watercolor titled “The Breakwater Cullercoats,” depicting an English fishing village and women waiting for their men to return.

The watercolors “Leaping Trout” and “Guide Carrying a Deer,” created in the Adirondacks, reflect Homer’s love of nature and the unspoiled moment of catching a fish, a favorite pastime of both the artist and the patron who bought the painting, Charles Shipman Payson.

In 1883, Homer’s family bought land at Prouts Neck along the rocky Maine coastline, where renowned Portland architect John Calvin Stevens transformed a carriage house into a studio and simple residence for the artist. It was here where Homer created some of the paintings now considered icons of American art.

The PMA acquired the studio, located 12 miles south of the museum, in 2006, and it is now being restored, with fall of 2012 as the scheduled opening date.

When viewing “Winslow Homer and the Poetics of Place” be sure to look for “Weatherbeaten,” an oil painting considered a national treasure, depicting the majesty and power of the sea rushing over rocks.

Also, be sure to examine “Wild Geese in Flight,” which shows two geese on the sand that have fallen from a flying flock. This painting has drawn at least two different interpretations — that the geese were shot by sportsmen or they died after slamming into a nearby lighthouse, not seen in the painting.

For the exhibit Denenberg prepared a well-written, hardcover catalog with beautiful colored plates. “We designed the catalog with a period feel, using a linen cover to preserve it and reflect the age in which Homer lived,” Denenberg said.

I could see “Winslow Homer and the Poetics of Place” again and again. It comes down Sept. 6.

The PMA, at Seven Congress Square, is open 10 a.m. to 5 p.m. Tuesday, Wednesday, Thursday, Saturday and Sunday; and 10 a.m. to 9 p.m. Friday. Admission is $10 for adults, $8 for seniors and students with ID, $4 for youths ages 6-17 and free for children under 6. Admission is free from 5 to 9 p.m. on Friday.

Pat Davidson Reef has a master’s degree in education and has taught art history at Catherine McAuley High School in Portland. She has written two children’s books, “Dahlov Ipcar, Artist,” and “Bernard Langlais, Sculptor.”