When Martha Spencer takes the Scruffy City Hall stage March 23 for the Honky Tonk Nighttime Ball, trading riffs on guitar, fiddle and mandolin with old friends Matt Kinman (Old Crow Medicine Show) and Alex Leach (Bill Stanley’s band), don’t be surprised when she suddenly drops her axe and starts cutting the proverbial rug in the middle of the show, engaging mountain music fans with a nimble display of traditional flattop dancing.

“There will probably be lots of trading instruments going on, and I’ll probably dance,” Spencer explains in a recent phone interview, speaking with a distinctive Appalachian drawl. “It’s a lot of fun, and it’s an interactive thing. In a lot of the bands I’ve played in, the crowds are dancing, so there’s often some give and take.”

Flattop, Spencer explains, is a dance form with Scots-Irish derivations, in which the soles of the performers’ feet usually hover no more than a few inches from the ground. It differs somewhat from its close cousins, clogging and buck dancing, in that it is quieter than clogging, and less high-kicking and physically demonstrative than either.

The West Virginia Encyclopedia online calls it “the mountain artistic reaction to hard-driving fiddle music.”

Though still a young woman, Spencer is already a globe-trotting veteran performer, having grown up as a member, along with her parents Thornton and Emily Spencer, of the long-running Whitetop Mountain Band — so named for a tiny town in the highlands of Virginia. Through her childhood years and over the course of innumerable music festivals and fiddle competitions, Spencer developed her alternately sweet and baleful singing style as well as her flattop dancing skills, and mastered every stringed instrument relevant to the traditional mountain repertoire.

“I never took lessons,” Spencer says of her flattop abilities. “I just picked it up from people that would come over to my parents house, or who I saw at festivals. I’d watch, and then I’d join in.”

In the years since, she’s toured extensively both stateside and overseas, playing a mix of traditional mountain music, bluegrass, and throwback country in a variety of contexts and configurations. “I grew up in the old-time mountain tradition; those are my roots,” she says. “But I love a lot of different music. I love bluegrass. I love George Jones and Merle Haggard, too.”

The upcoming Honky Tonk Nighttime Ball show will not be the first time she’s crossed paths with either Kinman or Leach. The three musicians have a considerable history together, Spencer says, having shared stages and guest-starred on one another’s solo records many times over the last few years. They have collaborated so often, in fact, that Spencer says the March 23 show probably won’t require much in the way of advance rehearsal. “We’ve played enough together that we can come up with a good mix of songs almost on the spot,” she says.

“We’ll probably do a variety of music — including some old-time mountain music with a little bit of dancing,” Spencer continues. “We’ll probably do some bluegrass, because bluegrass banjo is Alex’s thing. We’ll probably do some country and honky tonk as well. I’d say we’ll probably put some of our own stuff in there, along with traditional things that people might recognize.”

Martha Spencer will play the Honky Tonk Nighttime Ball at Scruffy City Hall on Thursday, March 23 at 8 p.m. as part of the Funny Ears Fringe Festival.