Madelyn Pugh Davis, who helped define the TV sitcom as the co-writer of every episode of “I Love Lucy,” the 1950s series that showcased the grape-stomping, bonbon-cramming, health-tonic-swigging antics of a scatterbrained housewife, died of undisclosed causes April 20 at her home in Los Angeles. She was 90.

A veteran writer of radio sitcoms, Davis became one of a handful of women who worked in the male-dominated medium of network television.

“She was one of the crucial people who really helped sustain one of the most dominant shows in the history of television,” said Ron Simon, a curator at the New York City-based Paley Center for Media.

In 2007, the publication Television Week named her one of the 25 most influential people who shaped the industry, noting that she was a principal writer on all 180 “I Love Lucy” episodes and 13 specials on CBS from 1951 to 1961.

The program was one of the top-three most-watched programs during its first six years on the air and won two Emmy Awards as best situation comedy. Forever in syndication, “I Love Lucy” made enduring household names of Lucille Ball and her real-life husband, Cuban-born bandleader Desi Arnaz, as well as Vivian Vance and William Frawley as their quirky neighbors, the Mertzes.

If the show’s premise wasn’t particularly innovative — the wacky housewife, the irritated husband, the oddball friends –“I Love Lucy” was elevated by the anything-for-a-laugh conviction of the four leading actors and the irrepressible inventiveness of the scripts.

The initial writing force behind the show included Davis (then known as Madelyn Pugh), her longtime writing partner Bob Carroll Jr. and their producer, Jess Oppenheimer. Writers Bob Schiller and Bob Weiskopf later joined the team.

Together they molded Ball, who had appeared in minor Hollywood dramas and comedies, into the lovably slapstick-prone Lucy Ricardo.

The show was propelled by a relentless physical humor, with Ball in one instance battling a giant loaf of bread that emerges from the oven and pins her to the wall. Other memorable sequences featured Ball slipping and sliding in a vat while mashing grapes and getting very drunk while filming a commercial for an alcohol-laced patent medicine called Vitameatavegamin.

Ball often credited the show’s writers for her success, and Davis returned the compliment.

“The great thing about Lucy, besides her marvelous comic talent, was she would do anything you wrote. There was never that ego saying, ‘I don’t know. I won’t look good,’ ” Davis told USA Today in 2001.

“We’d say, ‘Do you mind working with animals? Do you mind getting covered with clay? Do you mind letting someone slap chocolate in your face?’ ” Davis said. “She never said no.”

Davis said her favorite episodes included a 1952 show in which Lucy and Ethel land jobs in a chocolate factory, only to have the conveyor belt kick into overdrive.

Madelyn Pugh was born in Indianapolis on March 15, 1921. After graduating in 1942 with a journalism degree from Indiana University, she could not find work as a reporter and instead landed a staff writing job at a radio station in her home town.

Her career was soon boosted by World War II. With men away, she found herself in demand as a writer and soon was working for a CBS station in Los Angeles.

There, she teamed with Carroll on several shows.