Tiffany Evans f/ Bow Wow, “I’m Grown” (Columbia). Evans is 15 years old, a peculiar age at which to proclaim grown status, but maybe she is speaking in relative terms — she seems to be addressing a young gent who is accustomed to dating females who act more like freshmen than seniors. She does not really go into detail about what makes her grown; “You’re so stuck in the past, like stone-washed jeans” is the only line that could possibly trick someone into thinking she was born prior to the ’90s. There’s something appealingly Lil’ Klymaxx about her (more “Wild Girls” than “I Miss You”), and the track is one of the best Darkchild productions of late, crisp and ringing. Too bad Bow Wow showed up.

Michael McDonald, “Love T.K.O.” (Universal Motown). All respect due to the voice of “What a Fool Believes” and “I Keep Forgettin’,” not to mention the background voice of “Peg,” but please — no. If Teddy Pendergrass had a grave, he would be rolling in it.

Here is the full roster of new R&B entries on Billboard’s Hot R&B/Hip-Hop Songs chart for March 22 and 29, listed in order of position, along with ratings on a 0-to-10 scale and links to samples.

March 22, 2008
71. Liv Warfield, “I Decided” (7) MySpace
74. Jordin Sparks f/ Chris Brown, “No Air” (5) MySpace
92. Michael McDonald, “Love T.K.O.” (3) MySpace
98. Tiffany Evans f/ Bow Wow, “I’m Grown” (7) MySpace
100. Teyana Taylor, “Google Me” (6) MySpace

March 29, 2008
65. Mary J. Blige, “Stay Down” (5) MySpace
83. Jaheim, “Have You Ever” (7)
84. Grind Mode, “She’s So Fly (I’m So High)” (6) MySpace
90. One Chance, “U Can’t” (6) MySpace

Previously: January 19 (Ryan Leslie, Usher), January 26 and February 2 (Dear Jayne, Raheem DeVaughn, Cherish), February 9 and 16 (Johnta Austin, Charlie Wilson), February 23 and March 1 (Mariah Carey, Usher, Ashanti), March 8 and 15 (Estelle, Noel Gourdin).