Like father, like daughters? Well, yes and no.

Cassandra Christensen Barney and Emily Christensen McPhie may have inherited some of their father's (fantasy artist James C. Christensen) art genes, but they also have developed different approaches and styles that give them their own voices.

Which makes it especially delightful, they say, on the rare times when the get to "sing in harmony," as it were — when they get to have a joint exhibition of their artwork.

One of those occasions is an upcoming show at Art Access Gallery. The show opens Sept. 18 and runs through Oct. 7. An opening reception will be part of the September Gallery Stroll.

Another thing that makes this show so delightful, the artists say, is the theme: "Hortus Conclusus, or The Enclosed Garden."

They were sitting around one day, talking about ideas, explains Christensen. "I had done a 'Tree of Life' that was in an enclosed garden, and our discussion took off from there. We found the Latin term, and we realized there was a lot of symbolism, a lot of metaphors in the idea of an enclosed garden."

The traditional design of a walled garden, split into quarters separated by paths, dates back to the earliest gardens of Persia, he says. "The 'hortus conclusus' of High Medieval Europe was more typically enclosed by hedges or fencing, or the arcades of a cloister."

But the idea of enclosure was to create a protected and nurtured space, "where ideas and people, like plants and flowers, can flourish. The idea of a controlled safe place can represent the family, the community or even the space in one's own mind."

For Barney, the idea "got me thinking about what I want in my garden. It is an intimate space, where you can create your own paradise." In doing research for the show, she says, "I was delighted to find that the word paradise is, by definition, a walled garden. It is a place to learn and grow and create beauty. It's a safe place where there is celebration. But it also needs to be tended, because behind its walls is also a place to be vulnerable. There can be hummingbirds, but there can also be demons. This has been one of my favorite themes to work on."

As a mother of young children, McPhie's thoughts "immediately jumped to my kids." Her marionette-like images for the show "are a comment on parenthood, on how many decisions I make for them each day. And how do I know when it's time to cut the strings? When is it time for them to go outside the wall? There are so many emotions that go with those decisions."

And that, Christensen says, is really the fun part of working with his daughters — "the ideas bouncing back and forth, the what-iffing, the planning. I love these collaborations."