"Blossom" is about one-eighth as funny as its laugh track thinks it is. But hey, for a modern sitcom, that's not a bad percentage.

The new NBC series about a smart and sassy 14-year-old girl, premiering at 8:30 tonight on Channel 4 (then moving to Monday nights as of Jan. 7) is elementarily rudimentary in every respect but for its star, the magnetic sprite Mayim Bialik, who first got noticed playing a young Bette Midler in the execrably mawkish movie "Beaches."

Bialik does look like Midler, yes, and also like a young Margaret Hamilton, the actress who played mean Mrs. Gulch (and the wicked witch) in "The Wizard of Oz." In other words, by no means is she just another pretty face. But she is definitely an interesting face, and she has a fresh, quirky perkiness.

The producers -- including hitmakers Paul Junger Witt and Tony Thomas -- have given her very little support, however. The rest of the family consists of a dishwater dad who's supposed to be a musician (wan Ted Wass) and two highly glandular, numbskulled teenage brothers (Joey Lawrence and Michael Stoyanov).

NBC's publicity department, what's left of it, says one of the brothers is a "recovering substance abuser" (O, sign o' the times!) but this doesn't seem to come up in the premiere. No, the premiere is more concerned with menstruation, as Blossom crosses the biological threshold into womanhood, and the writers exercise their freedom of expression by using the word "period," in its gynecological sense, 10 times.

All the cast members become slaves to this ide'e fixe, and several of the jokes involve boxes of sanitary napkins. It's always so thrilling when TV logs one of these milestones.

There are two lonely deft touches. In one, Phylicia Rashad appears in a fantasy sequence as The Utterly Perfect Mom, illustrating her lecture on the human reproductive system with a cake froster. The other occurs near the fade-out, when daughter and dad share an affectingly and mercifully quiet moment.

The reason Blossom has to fantasize a mom is that hers has left the family. When last seen, she was running around Paris pursuing a career (how typical can you get, huh?). As has many another sitcom in the fairly recent past, this one gratuitously makes an unseen mom the heavy and suggests that jobs turn women mean. It's bunk, but strangely persistent bunk in the male-dominated world of network programming.

The perpetually pixilated Eileen Brennan offers welcome respite from the dull dad and the dumb sons in her role as Agnes, a wacky neighbor and confidante of Blossom's. Agnes seems to live next door, or thereabouts. It doesn't really matter where; anything that gets Blossom away from her own cliche-ridden household is to be encouraged.