Carlene at Johnny Cash's funeral service, quoted by CMT.com:

June was the flower. Johnny was the vase and the water that held it
up." His stepdaughter Carlene Carter said, "He was my father by soul.
We Carters became Cashes when the Cashes became Carters. I'm glad
June and Johnny are together in heaven. She's got cheesecake in one
hand and a charge card in the other, and he's now an Indian."

To date, there never has been released a Carlene Carter/Johnny Cash
duet. The closest thing were brief cameos on each other's songs. Cash
did a turn as a funky basso background singer on Carlene's "Go Wild"
(on the "Little Acts of Trason" CD). Carlene sang with sister Rosey
and half-sister Rosanne Cash on the chestnut "Ole Slewfoot," which
appeared on 1974's "The Junkie and the Juicehead Minus Me." That LP --
one of many albums in Cash's discography that have yet to make their
way onto CD -- also marked Carlene's solo debut (as well as Rosanne
Cash's). She sang "Friendly Gates" on that album (while Rosanne Cash
did Kristoferson's "Broken Song of Freedom"). During Carlene's stint
as a singer with the reconstituted Carter Family, she appeared as a
background singer on several of Cash's late '80s records. And, as
noted here just a week ago, Carlene and Cash also appear together on
several songs on June Carter Cash's farewell CD, "Wildwood Flower."

Like many, many others, I always counted Johnny Cash as my favorite
singer. I suspect most people who are Carlene Carter fans heard of
her and her music first either through Johnny Cash or Nick Lowe. I'm
one of those in the former camp.

In many ways, those of us who are fans of the Cashes and Carters as
fans, rather than friends or family, will not have our relationship
with the Man in Black altered. It sounds like there are hundreds of
unreleased songs in the can, and as noted, CBS/Sony has been
incredibly slow in rereleasing Cash's best material from the 1960s
and 1970s. So, there will be lots of new product to enjoy in years to
come.

Still, as many have noted, it's hard to imagine that, from this point
forward, we will leave in a world without Johnny Cash...