Flower power pop-rock singer Scott McKenzie was found dead in his home in Los Angeles on Sunday (Aug. 19). The 73-year-old is best known for his 1967 hit ‘San Francisco (Be Sure to Wear Flowers in Your Hair),’ and as a long time friend of John Phillips from the Mamas and the Papas.

The BBC reports that McKenzie had been suffering from Guillain-Barre syndrome (a disease that affects the nervous system). A neighbor said he died of a heart attack. Born Philip Wallach Blondheim in North Carolina, he changed his name after comedian Jackie Curtis said the singer resembled a Scottie dog (via Rolling Stone).

McKenzie and Phillips first formed a band as teenagers, and then became the Smoothies as they played gigs in New York City. In the early ’60s, the two teamed with a banjo player to form the Journeymen. When they broke up in 1964, Phillips went on to form the Mamas and the Papas as McKenzie decided to remain a solo artist. It was Phillips who wrote McKenzie’s biggest hit.

McKenzie was also a strong supporter of Vietnam veterans, dedicating every American performance of ‘San Francisco’ to them, and singing at the 20th anniversary of the dedication of the Vietnam Memorial Wall in 2002. His song became something of a symbol for the Flower Power movement.

In 1988 McKenzie helped pen the Beach Boys hit ‘Kokomo.’ In his later years he took to writing poetry.

Watch Scott McKenzie Perform ‘San Francisco (Be Sure to Wear Flowers in Your Hair)