You want to know about the hair? Michael Landon will tell you about the hair. Usually, it's the size of a chef's toque, silver-streaked and blow-dried from here to New Jersey. Today it looks like a fizzled souffle', but you'd still need a wide-angle lens to shoot it.

"I have something about hair," Landon says. "I was positive when I was a kid that God had given me a gift, the same as Sampson had."

He's kidding.

"No I'm not kidding," says Landon, who cascaded into middle age on the country's collective Magnavox, from Little Joe Cartwright on "Bonanza" to the frontier father-knows-best on "Little House on the Prairie." "I weighed 125 pounds in senior high school and I was the best javelin thrower in the United States by far. Well that just doesn't make sense. But it does to me because I'd let my hair grow longer and longer and longer."

At the University of Southern California, the football players thought Landon was a weirdo with all that hair, so they held him down and shaved his head and Michael Landon says his strength was gone. Finito.

He couldn't throw the javelin anymore. He quit school. He doesn't know now whether it was psychological or physical, and he isn't about to find out by trying out for "The Telly Savalas Story."

"I'd have to do it lying down. I don't think I'd have the strength to get on my feet."

He's a handsome devil at 47, in faded denim shirt, jeans, crocodile boots and a tweed jacket. His face is tan and taut. His smile is warm, his voice low and sexy. He doesn't wear a lot of silver jewelry like some other macho guys from Malibu, although maybe a chain or two wouldn't look out of place nestled in the hairs of his barrel chest.

"I'm not smart unless I'm strong," he says by way of explaining his 5-foot-10-inch, 165-pound physique. "Unless I go to a gym and exercise I feel stupid."

Landon was in town to promote "The Chemical People," a two-part PBS series addressing the problems of teen-age drug and alcohol abuse to be aired Nov. 2 and 9 at 8 p.m. On Monday at the White House he taped an introduction to the series with Nancy Reagan, to be shown by PBS tomorrow night.

Landon knows a lot about drugs. He was once hooked on Miltowns, and, more recently, his stepdaughter Cheryl nearly killed herself on them.

"I suspected it during her last two years of high school. Then she went to the University of Arizona. And I used all the excuses; no matter what she told me I would believe because I wanted to believe. While she was at the university, she became more involved in drugs. Grass, alcohol, cocaine, amyl nitrate. Poppers, downers. She was in an automobile accident there and everyone was killed except her and that just gave her an excuse to do more drugs because of what she had gone through."

At the age of 19, she overdosed on a combination of pills and nearly died.

Along with sadness and grief, there were feelings of anger on the part of her parents. "You get very guilty about some of the feelings you have about your own child, one of which is, 'I wish she did not exist. If she didn't exist, I wouldn't feel all this pain.' "

The first thing Michael Landon did was get help from psychiatrists. Once he found out the doctors were prescribing other pills, he sent his daughter to Cedu, a drug rehabilitation program in Running Springs, Calif., where she stayed for more than two years, finally kicking the drug habit.

"She's actually in many ways very much stronger than she would have been otherwise," Landon says.

His own drug use, he says, is also a thing of the past.

"The only time I was ever involved with drugs was the second year of 'Bonanza' and I was only involved with a drug called Miltown at that time. It's the same type of thing as Valium or Equanil. I want to tell you something, it was murder. Absolute murder. It was so bad that I couldn't sit up, I couldn't get out of bed in the morning. I would have to very slowly reach to the nightstand and take four pills and just let it settle in, because if I sat up, I'd get a migraine headache and hear the blood pumping in my ears. I couldn't take a fast step. I mean, I was a guy who was always very athletic and I had to stop all of that. I'd do a fight scene on 'Bonanza' and I'd have to go to my dressing room and throw up from the pain."

The drugs--often as many as 50 or 60 pills every three days--were prescribed for anxiety, a condition Landon says was brought on by sudden fame at the age of 20. "I thought I was prepared for it, but I guess I wasn't."

Landon was born Eugene Maurice Orowitz and grew up in Forest Hills, N.Y. The kids in school called him "Ooogy," he doesn't know why. He says when he started acting the studios suggested he change his name. He found his current one while flipping through a phone book.

"I thought, 'Alf Landon,' you know. That wasn't bad."

After leaving USC, he tried out for a few acting jobs and landed the lead in the film "I Was a Teenage Werewolf." He had also started a singing career at the age of 18 and toured the country with Jerry Lee Lewis, singing "Gimme a Little Kiss, Willya, Huh?," which he cut for Candlelight Records. "Linda Is Lonesome" was the flip side.

But more about his hair.

"I never had one date when I was in school because girls were terrified of me. I took one girl out once and we went to a hamburger place and I was the shyest guy you can imagine, but because of my hair, this girl got a note from the waitress which said, 'Be Careful.' I couldn't believe it."

When he appeared on "Bonanza," he used to dye his hair. Medium Ash Brown. And he also cut it himself because he has "a thing" about crowded places. The first year he went to the Emmy Awards he left after 10 minutes. He also bites his nails and does a terrific Yiddish accent.

He has been married three times. His first ended in divorce. His second, of 19 years, ended in divorce in 1981. On Feb. 16 of this year, he married 25-year-old former makeup artist Cindy Clerico, and two months ago their daughter Jennifer was born.

Which makes Landon the father of eight. He has four children from his second marriage and three adopted children from his first and second marriages.

The actor says he wants one more.

Will he survive that long?

"My hair will last," he says, crossing his crocodile boots and lighting another Carlton. "My whole body will be gone. It will just be hair in a coffin."