Joni Mitchell's health crisis - the Canadian songwriter was found unconscious March 31 in her Los Angeles home and rushed to the hospital - put a scare into legions of fans. Many can't get that line, "You don't know what you've got till it's gone" - from "Big Yellow Taxi" - out of their heads.

Mitchell, 71, hasn't released a new album since 2007's Shine. Even ardent followers who scooped up last year's high-concept, self-curated box set, Love Has Many Faces: A Quartet, A Ballet, Waiting to Be Danced, or celebrated a victory against ageism when she was featured in an Yves Saint Laurent ad campaign, would admit her greatest work was decades behind her.

But then, as now, you don't have to go very far in the singer-songwriter universe to encounter the presence of Mitchell, who "continues to improve" and "is resting comfortably" in an L.A. hospital, according to her website. No details about her illness have been released. Despite media fixation on the controversial Morgellons disease she says she suffers from, it's unclear what role, if any, it plays here. Or whether there's a link to her history with post-polio syndrome.

In the last couple of months, listeners to the final run of retiring Philadelphia DJ Gene Shay's Folk Show on WXPN have been treated to replays of his mid-1960s interviews with Mitchell. At the time, she was playing extended runs at clubs like the Second Fret in Center City or the Main Point in Bryn Mawr.

When I interviewed Katie Crutchfield of Waxahatchee a few weeks back, the 26-year-old Philadelphia songwriter (her new album, Ivy Tripp, comes out Tuesday) talked about Mitchell and a certain color that keeps coming up in her song and album titles.

A tune called "Blue" is on Ivy Tripp, and on her 2013 album Cerulean Salt, you'll find an equally melancholy song named "Blue, Pt. II." When Crutchfield, who will play Union Transfer on Wednesday, was recording that album, she considered titling it Blue, forgetting for a second that it's the name of Mitchell's 1971 masterpiece.

"That record really means a lot to me," Crutchfield said. "It's one of my favorite records of all time." When she told bandmates Kyle Gilbride and Keith Spencer she was kicking Blue around as an album title, they "looked at me like, 'You can't do that,' " she says. "I wasn't thinking at the time." So she went for cerulean, a shade of blue.

I went digging back into The Inquirer archives for a 1994 interview I did with Mitchell, when she was promoting an album called Turbulent Indigo. (Close to blue.) She had a lot to say about her predilection for sad songs, who her true peers are, and the first music that ever slayed her.

"I just like beautiful music, and most beautiful music is sad," Mitchell said, smoking cigarettes and drinking coffee. "I remember the first piece that really made me swoon. I heard it in a Kirk Douglas movie called The Story of Three Loves. It was Rachmaninoff, Variations on a Theme of Paganini. I was just a baby" - 10 years old, in Saskatoon, Saskatchewan - "and I didn't have any money. So I would go downtown to the record store, where you could go into a glass booth, take the 78s out of their brown paper, and listen to see if you liked them. And I would listen to that over and over again. To this day, it's the saddest and most beautiful piece of music I've ever heard.

"Every piece of music, as melancholy as it may sound, I play for fun," she said. "For the most part, my love of melody tends toward those kinds of complex, emotional chords. You can't put jolly little words to that kind of thing."

Mitchell, who was born in Fort Macleod, Alberta, said she switched from ukulele to guitar with the help of a Pete Seeger instructional record. She also said Bob Dylan's "Positively Fourth Street" changed her as a songwriter: "I thought a song was a song and a poem was a poem. But that particular song was a song about anger that was very well put. And I thought, 'We can write about anything now. The door is ajar.' "

Mitchell, of course, has had an enormous impact on female singers. Back in 1994, those in her debt included Tori Amos, Shawn Colvin, and Julia Fordham. She stressed, however, that "I've never considered myself a feminist. It's too 'them' and 'us.' It's too apartheid. I'm more interested in unification. So to be lumped in with all the other women is not my proper place. I think of my group as Leonard [Cohen], Neil [Young], Dylan, and myself. And I wouldn't expect these younger artists to strive for the standards that I have as a writer. It's too demanding."