JOHN S. M'GROARTY, CALIFORNIA POET, 81 Ex-Congressman, Playwright, Lawyer Dies—Championed Townsend Old Age Plan Special to THE NEW YORK TIMES.     LOS ANGELES, Aug. 7—John Steven McGroarty, Los Angeles Times writer and California poet laureate, died tonight at St. Vincent's Hospital. His age was 81.     At the bedside during the beloved writer's last hours was a small group of his closest relatives and friends. Play Ran for 20 Years     Mr. McGroarty was the champion in Congress of the Townsend old age pension plan, although he later introduced a bill which provided $100 a month, instead of $200, to persons 60 years of age. He was nearly 40 years old when he moved to California from Pennsylvania, yet he became one of California's chief historians and his "The Mission Play" ran for twenty years at San Gabriel. It was presented again during the international exposition in San Diego in 1936.     The California legislature elected him State poet laureate in 1933 and there was a move while he was in Congress to make him national poet laureate. For years he conducted a Sunday newspaper column of homey comment, which turned to political comment while he was in Washington.     Born in Luzerne County, Pa., the son of Hugh and Mary McGroarty, he was granted a State certificate at the age of 16 and taught school for two years to enable him to complete his education at the Harry Hillman Academy in Wilkes-Barre. Later the Universities of California and Santa Clara conferred degrees upon him.     At 28 he became treasurer of Luzerne county, setting a new age record for that office in Pennsylvania, and married Ida Lubrecht. While serving as county treasurer he studied law and was admitted to the bar in 1894. Marcus Daly, copper leader, induced Mr. McGroarty to serve on his legal staff in Butte, Mont., in 1896. After Mr. Daly's death he went to Mexico on a mining venture and at the turn of the century arrived, with his wife, in Los Angeles.     The death of a German munitions manufacturer inspired Mr. McGroarty to write a poem which was published in the Log Angeles Times and led to a friendship with the publisher, Harrison Gray Otis, and a long connection with that newspaper. Crusader for Landmarks     Seeing old missions were being used to store grain and stable horses, Mr. McGroarty became a crusader for preservation and restoration of early California landmarks. More than two million persons paid admission to see his historical mission play. He wrote three other plays, "La Golondrina," "Osceola" and "Babylon," and also was author of "Poets and Poetry in Wyoming Valley," "Just California," "Wander Songs," "The King's Highway" and "California—Its History and Romance."     Mr. McGroarty was elected to Congress in 1934 and served two terms. A Democrat, he went in pledged to support New Deal policies, but left office a strong opponent. He balked at President Roosevelt's Supreme Court and reorganization plans.     Championing the Townsend pension plan, he gave consent in 1936 to have California delegates to the Democratic National Convention instructed for him for President in order to win support for the plan, but Dr. Francis E. Townsend opposed this move. Later he broke with Dr. Townsend, whose plan called for $200 a month for pensioners, and introduced what he termed a more conservative bill, calling for up to $100 a month to be raised by a 2 per cent transactions tax.     In the spring of 1938 Mr. McGroarty announced he was through with politics and would retire to his ranch at Tujunga, resuming his role as "Sage of the Verdugo Hills." But soon he was in the thick of it again, seeking the Democratic nomination for California Secretary of State. He was however, defeated in the primary.