At the risk of sounding like the Comic Book guy on “The Simpsons,” last week had to be the worst “American Idol” (7 p.m., Fox) ever! The Latin music challenge left everybody off balance. With few exceptions, the contestants chose safe, upbeat numbers that would not be out of place at a wedding or office Christmas party aboard a cruise ship. And as a mentor, Jennifer Lopez was scrupulously inoffensive.

Martina McBride is aboard as guest mentor and performer, so this must be country week. Will things go as badly as the Latin excursion? None of the remaining seven contestants seems to have an affinity for achy-breaky hearts. On the other hand, the resident divas should have no trouble with ballads. Besides, contemporary country music has become broad enough to engulf and devour sounds that years ago would have fallen into the categories of rock, pop, folk and gospel.

Melinda Doolittle remains the one unassailable presence here. She’s brilliant, even when she’s not dazzling. But one can’t help feel that she’s simply too mature, too dignified and too talented to rise to the top of the heap of what is essentially a teenage popularity contest.

¢ There was a time when something named “The Green” (8 p.m., Sundance) would have to be about the groundskeepers at the Augusta National tidying up for the Masters.

How 20th century.

This 13-part series, presented by Robert Redford tonight, will air every Tuesday, with short films about the environment and things viewers can do to change their wasteful, polluting ways. It kicks off with “Big Ideas for a Small Planet: Fuel” (8 p.m.), a look at the decades-long search for alternatives to gasoline-powered engines. “A Crude Awakening: The Oil Crash” (8:30 p.m.) follows, arguing that the era of cheaply obtained oil is ending quickly.

¢ “Nova” (7 p.m., PBS, check local listings) presents “First Flower,” a horticultural detective story that ranges from a remote region in western China to the laboratories of universities in Europe and America.

Although flowering plants – from roses to wheat to dogwood trees – comprise the vast majority of contemporary plant life, they are a relatively recent evolutionary arrival. Scientists try to place the date of the origin of the first flower and argue about it using fossil evidence and the latest in DNA technology to make their cases.

Tonight’s other highlights

¢ Scheduled on “Dateline” (7 p.m., NBC): A young girl’s murder and two subsequent confessions shatter a small town.

¢ Lorelai and Luke hash it out on “Gilmore Girls” (7 p.m., CW).

¢ Wet work in a tropical climate on “The Unit” (8 p.m., CBS).

¢ A 6-year-old suffers from a grown-up malady on “House” (8 p.m., Fox).

¢ The results are read on “Dancing with the Stars” (8 p.m., ABC).

¢ Doll morality on trial on “Boston Legal” (9 p.m., ABC).

¢ Shane suffers as Vic nears Lem’s suspected killer on “The Shield” (9 p.m., FX).

¢ “Secrets of J. Edgar Hoover” (9 p.m., National Geographic) looks at the enormous clout of the FBI director’s 50-year career.