Radical in its time (the mid-20thcentury), these days bluegrass is sometimes called "oldtime music." It isn't. True, its roots lie in the Southern stringband tradition of an earlier era, but the style itself arose from the creative imagination of Grand Ole Opry star Bill Monroe. Bluegrass is, in fact, a modern music.

It's perhaps wise to keep that in mind when one listens to the HillBenders as one wonders when bluegrass ceases to be bluegrass and becomes something else as yet unnamed. (No, "Americana" doesn't count.) It is often said that country music is what gets played on country radio. Maybe we're at a point at which bluegrass is what gets played at bluegrass festivals.

The HillBenders hail from Missouri, most famously to bluegrassers the state where the Dillards grew up before relocating to Los Angeles to become one of the three favorite bluegrass bands -- Flatt & Scruggs and the Greenbriar Boys being the other two -- of the folk revival. The three pure-bluegrass albums the Dillards cut for Elektra in the mid-1960s sound great to this day. Then, as folk and related music lost popularity, the Dillards transformed themselves for a time into a country-rock outfit which influenced late-1960s/1970s bands such as the Flying Burrito Brothers and New Riders of the Purple Sage.

Bluegrass, like jazz, performance requires a high level of technical proficiency. You have to be in command of your instrument, and if you aren't, don't bother. Inevitably, some master pickers challenge themselves by exploring genres and techniques outside bluegrass. For good or ill some of these bump up against bluegrass' guardrails, while others happily expand the vocabulary.

You can hear the HillBenders either way. You might want to know that their previous release (unheard by me) consisted of a recreation of the Who's rock opera Tommy played on bluegrass instruments. This time around, the songs are originals. Some of the 11 cuts are reasonably straightforward contemporary bluegrass in the evolutionary line from the Country Gentlemen through Newgrass Revival and beyond. There is even a reworking of the old minstrel tune "Who Broke the Lock on the Henhouse Door," here titled "Don't Look at Me." (It was first recorded in 1929.) Mostly, however, this eponymous disc shows its debt to country-rock, mainstream country, pop and jazz, with sometimes folkish lyrics, unfailingly intelligent.

It's pretty good if you're not too fussy about genre classification. The songs are ably crafted and interestingly arranged. Bluegrass or otherwise, it does the job, which is to please and move the listener.

Her history in the genre notwithstanding, Missy Raines's Royal Traveller is not a bluegrass disc. Because my musical (and other) memory goes back a few years, I think for some reason of Tom Rush's mid-career albums which he filled with songs mostly composed by others. Rush's taste was exemplary; it was he who first covered the likes of Joni Mitchell and James Taylor. If Raines doesn't quite manage that, she certainly has an ear for a better-than-ordinary song.

Alison Brown, who produces Royal Traveller, places the songs within acoustic textures, with elements of bluegrass, country and even oldtime including a number by Ola Belle Reed and another by the Carter Family. Raines, moreover, has the wisdom to choose Robbie Fulks' "Goodbye Virginia." Fulks is every bit as gifted as John Prine; yet he's never experienced Prine-level popular acclaim. I wonder how many reading these words have ever heard of him. Still, the bulk of the songs are Raines originals and co-writes.

As with the HillBenders, some of this is not the sort of sound I'm automatically drawn to. So I was surprised to like it immediately. Raines is a nuanced vocalist and a thoughtful interpreter. I've heard a fair number of strong covers of Reed's "I've Endured," but even amid stiff competition this one stands out. I confess I am fonder of the more rooted side of Raines's repertoire than the singer-songwriter-pop side, but I am aware that's a matter of personal preference, not an esthetic judgment. There is a lot to charm the listener in Raines's quiet-spoken but emotionally compelling way with a song.