A garden grows in the Minnesota Museum of American Art

As gardens grow, the elegant one in downtown St. Paul came on fast. Within the past month, artists Harriet Bart and Yu-Wen Wu channeled a river, installed rocky cascades and pathways lined with blossoms.

Working by the light of a rising moon and shimmering water, they dissolved thick blankets of snow, sowed lush fields of tall green grass, swept in a flutter of pink petals. Now butterflies hover in the sparkling light, harbingers of summer days to come.

Theirs is an enchanted garden, readily glimpsed through the tall, street-level windows of the Minnesota Museum of American Art in the historic Pioneer Endicott building. At its official unveiling Saturday night, the garden will be a party scene. Students from nearby McNally Smith College of Music will perform musical riffs inspired by the artists' wall drawings, including random arrangements of black dots reminiscent of musical scores without key or clef signatures.

As its gallery setting implies, the Bart-Wu bower is a conceptual garden that includes real rocks and flowers but uses video, books, magnifying glasses and wall drawings to metaphorically evoke other elements of nature. They designed, built and assembled it over the past four weeks as visitors came and went, chatted and asked questions, even contributed ideas. It's on view through April 12.

Their river is a sinuous ribbon of crushed glass that sparkles in the sunlight as it ripples down the center of a 50-foot-long strip of tarpaper. The butterflies are translucent images affixed to magnifying glasses suspended from the ceiling like a crystalline forest.

At the head of the glass river, a wall-sized, mostly black-and-white video continuously shows the seasons changing in highly abstracted form. The full moon rises from a dark void, arcs through scudding clouds and enlarges into a circle of light glimmering on water spattered with rain drops. From the water arise thin columns of words, poetry that melts into mist or confetti-sized snowflakes. Thick grass, distant trees and hedge rows, the Stone Arch Bridge, rushing water and then the cycle begins again.

"We started with the title, 'Random Walks and Chance Encounters.' That was crucial," Bart said.

"But we had many, many years of conversation," Wu added. "We did two site visits here, then e-mailed ideas and texts, had coffee and conversations, sketched it out, photographed and built it."

A Minneapolis resident, Bart met Boston-based Wu five years ago when both happened to be artists-in-residence at the Virginia Center for Creative Arts in Amherst, Va. Their studios were across the hall from each other. Bart was scrubbing the paint-spattered floor in hers, meticulously excavating traces of the 46 artists who had previously worked there. Wu suggested she document the spattered pentimenti of those lives; then she loaned her a camera. Bart turned the results into "Ghost Maps," an artful book that won a 2015 Minnesota Book Award.

Their friendship grew from that "chance encounter," a phrase that Bart has often used in her work before. Wu, meanwhile, was developing drawings and video images derived from things observed on what she calls "random walks." While her strolls may appear aimless, they are in fact contemplative times when she closely observes and sometimes records her surroundings.

Spontaneity is a recurrent motif, including in the title of a book that the artists have disassembled, taped to a wall and altered with dots, cuts and poetic additions (more butterflies). Called "A Field Guide to Getting Lost," by Rebecca Solnit, the book, too, is a meditation on that peculiar space-time continuum defined by memory and musing.

"Everything here has a narrative about it," said Bart, pointing to a rectangular assemblage made of strips of ash wood whose undulating surfaces suggest a topographical map with hills, valleys, cliffs, ravines and river deltas.

Visitors are encouraged to contribute to the conceptual garden by adding dots to a (warning: pun ahead) "Dot COM.munity" on one wall, or placing in a shallow bowl something they've picked up on a recent walk. Besides interesting rocks and pebbles, contributions include a feather, a bit of film, some nested seashells, part of a hair clip, one die, a dried tomato and a small gray plastic insect-monster.

Introspective and intensely private by temperament, the artists have found their month-in-the-studio limelight challenging but ultimately fun.

"It's been a great time, really great," Wu said.

"We want to take this show on the road," Bart said, as both laughed.

Mary Abbe • 612-673-4431