As legalization day looms in Canada, images of cannabis are everywhere.

But in 1970, marijuana was apparently a more mysterious substance that not many people could recognize.

One of several 'youth drugs'

Marijuana is "chopped-up stems, leaves ... with the seeds filtered out," according to Dr. Lionel Solrush. (CBC Archives/Take 30)

"It just looks like oregano, or any chopped-up plant," Dr. Lionel Solursh explained to Adrienne Clarkson and Ed Reid, hosts of the CBC-TV program Take 30.

Helpfully, the afternoon current-affairs show aimed at homemakers had invited Solursh to help viewers identify marijuana and other drugs.

"There's an entire group of drugs which could be loosely called 'youth drugs,'" said Solursh. "They produce illusions, or distortions, of what you see and hear ... one of the mildest probably is marijuana."

Marijuana was often in the headlines at the time as the focus of a federal commission examining whether it and other drugs should be decriminalized.

The trio regarded a cannabis twig displayed on a rolling paper before Solursh shook another sample out of a small bottle.

"What distinguishes it [from common herbs] is the smell and the chemical content," said Solursh, who went on to describe the ways marijuana could be consumed.

He said it could be smoked like a cigarette, with or without tobacco; boiled as a tea and drunk; or injected.

It was edible too

"You can put it in brownies, can't you?" asked Reid.

"You can bake it in brownies, or fudge," agreed Solursh. With a smile, he added: "It's surprising you would know this, but very interesting."

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Clarkson referenced the movie I Love You, Alice B. Toklas, which had come out 15 months earlier and featured pot brownies in the plot.

"If a parent thinks that their child has been smoking marijuana, can they tell by any physical signs?" asked Clarkson.

"The only constant physical sign is a reddening of the eye," said Solursh. "Behaviour might be affected if the youngster has had a high enough dose and has been able to inhale it and absorb it. He might ... show off-judgment, timing, motor co-ordination."

An unmistakable scent

To help parents identify signs of marijuana use in their teens, CBC's Take 30 asked Dr. Lionel Solursh for a few tips on what to look for. (CBC Archives/Take 30)

But there was another sure sign someone had smoked marijuana in the house: the smell.

"Once you've smelled it, it's pretty distinctive," said Solursh. "It's something like burning insulation. Between that and a bonfire."

"So either your house is on fire or your child has been smoking marijuana," said Clarkson, with a laugh.

The discussion then moved to marijuana's long-term effects, which Solrush said were as yet unknown or based on studies involving hashish, a different substance derived from the cannabis plant.

And then there was the law.

"You can get up to seven years for possession," cautioned Solursh. "If you happen to give some to a friend ... you can get up to life in prison in Canada."