JIM LEHRER: Now, Margaret Warner wraps up her reporting trip to the Middle East nation of Yemen with the story of its most prevalent homegrown product.
MARGARET WARNER: If you want to get something done in this country, try to do it before 3:00. Soon after, Yemenis' cheeks are bulging with the mildly narcotic leaves of Yemen's number one cash crop, qat. For an overwhelming number of Yemenis of all stripes, getting buzzed on qat is a daily pastime.
ABDULLAH AL-SHEIKH, office director (through translator): Qat in Yemen existed for a very long time, and it represents one of the social traditions here in Yemen. Qat is a connection between family and friends.
MARGARET WARNER: Like his family and friends, office director Abdullah al-Sheikh started chewing qat in his teens. They gather like this, with bags of leaves and bottles of water, for hours at a time, talking politics, family, and tribal matters, and sharing jokes.
Whatever the topic, everyone's eager contribution is fueled by what aficionados say is a gentle speed-like buzz brought on from chewing the leaves. The feeling has been compared to several cups of espresso, or that first glass of wine, but it goes on for hours.
BASHEER AL-ARHAB, tribal sheik (through translator): Without qat, you get bored after maybe half-an-hour and maybe want to leave. But, with qat, you take much longer, four hours or more, because qat gives you the feeling you want to talk about your plans, your future.
MARGARET WARNER: Yemeni legend has it that qat's properties were discovered by a goat herder, who tried it himself after noticing his goats were more energetic while they were grazing on the leafy plant.
But it's a thirsty plant to grow, and given the drought gripping this part of the world, that means Yemenis' taste for qat comes at a high environmental cost.
In the rural village of Haddah (ph), rows of cactus have taken root where fruit trees once flourished.
AHMED AL-QADHEEM, farmer (through translator): This used to be a forest of trees. It was just like paradise. You could hardly see the other side of the valley.
MARGARET WARNER: Family farmer Ahmed Al-Qadheem says Haddah used to be watered by 12 natural springs and 20 wells. But, after two decades of drought and heavy consumption, they have run dry.
AHMED AL-QADHEEM (through translator): Now my farm's dried up. There's not enough rain, and we use too much water
MARGARET WARNER: Cities like the capital, Sanaa, are endangered, too. Its water table is dropping fast from the drought, an exploding population, and qat farming nearby.
Many city residents, the ones who can afford the skyrocketing prices, now rely heavily on water trucked in from rural areas. And the World Bank predicts that, within 15 years, Sanaa could be the first capital city in the world to run out of drinking water entirely.
But that hasn't stopped local qat farmers, who either don't know or don't care for modern irrigation methods, from flooding their qat fields, as their families have done for generations.
KAMAL MOATH, farmer (through translator): Depending on the season, I water my fields sometimes six, sometimes 12 hours a day.
MARGARET WARNER: The view over the village of Wadi Dhahr shows acres of trees below, bearing not fruit or vegetables, as they used to, but qat as far as the eye can see.
Farmer Kamal Moath explains why.
KAMAL MOATH (through translator): Growing qat, we are able to make a lot more money, and the government doesn't promote growing fruit or much else.
MARGARET WARNER: With qat now representing over a third of Yemen's agricultural output, farmers are drilling ever deeper to quench their plants. And the government helps them do it by selling diesel fuel at a below-market rate.
Deputy Finance Minister Jalal Yaqoub is worried about the trend.
JALAL YAQOUB, Yemeni deputy finance minister: We're subsidizing the depletion of water, and we're subsidizing the people who chew qat, and it's just not -- it's not right.
MARGARET WARNER: But he acknowledges there is an economic benefit. The lucrative qat trade keeps money circulating in the countryside, so life in poor villages remains vital.
DR. RAUFAH HASSAN ALSHARKI, Cultural Development Programs Foundation: Qat gives opportunity for people in countrysides to have access to money, without the government providing anything.
MARGARET WARNER: Raufah Hassan Alsharki, who runs an NGO in Sanaa, expresses a view shared by many, that the government doesn't try to restrict water use or qat consumption for another reason.
DR. RAUFAH HASSAN ALSHARKI: People in the politics found it easy to control people who are chewing qat all the afternoon and busy in doing other things, instead of asking for services or doing anything. And they cannot revolt. They cannot demonstrate. They don't do anything.
MARGARET WARNER: The cost to productivity is an issue. Though laborers use qat to keep them going, other chewers seem to spend their afternoons in a drugged-out haze.
Yacoub insists this is not deliberate on the government's part, but providing alternatives to qat, whether for work or play, would be a huge undertaking.
Yacoub insists this is not deliberate on the government's part. But providing alternatives to qat, whether for work or play, would be a huge undertaking.
JALAL YAQOUB: It is a serious lack of prioritization in -- from the government -- on the government's part not to focus on -- on fighting the use of qat. But you cannot just fight qat for the sake of fighting qat. You have to give other, you know, parts of the package.
MARGARET WARNER: These students aren't waiting for the government. They have launched their own anti-qat campaign to urge other young people to do something else.
Marwa Ba'abbab and Firwas Shamsan (ph), both in their 20s, say qat-chewing among their peers is holding them back.
MARWA BA'ABBAB, student: They say, OK, if I'm not chewing, where should I go? I will be walking on the street. They don't have the awareness, as I said, and they don't have like guys to tell them, no, you can go do voluntary work. No, you can do -- you can go to a gym or something like that.
MAN: And that's the problem here. They need to kill the time by chewing qat.
MARGARET WARNER: Abdullah al-Sheikh and his friends, their wads of qat growing with each chew, wouldn't disagree.
ABDULLAH AL-SHEIKH (through translator): People have to understand the damages of qat, that qat damages health, that qat wastes your time and money. I think the government has to implement some programs to stop qat-chewing.
MARGARET WARNER: But, this evening, qat is playing an irreplaceable role in this celebration of an upcoming wedding. Without it, the music may not play as loud, nor the party last as long, in a country where qat is king.