On the south side of Mercado Sonora, near the Merced Market, in Mexico City, there's an herb stall operated by Jaime (pronounced HAI-mee) García Galván and his wife, Paulina Rivera García. Usually Jaime is found doing exactly what the photo at the left shows, arranging his herbs. Paulina always sits on a tiny stool beside the stall taking care of sales and keeping the herb heaps organized. One day Jaime invites me to go with him and Paulina on one of their herb-collecting trips.

As we make our plans, Jaime always does the talking, but he ends almost every statement with a glance at Paulina, and an "Isn't that so?" Usually Paulina quietly nods in the affirmative, but sometimes she adds the absolute minimum needed to clarify or correct. During several pre-trip visits, sometimes I find Jaime sitting low in the stall, briefly resting with his head on a pile of herbs, but Paulina always works, almost obsessively, if only looking for brown or tattered leaves. Both Jaime and Paulina are about thirty-five years old.

Jaime and Paulina specialize in just a few kinds of herbs, so they are unlike those vendors in the Sonora who perch next to great heaps of dozens or even hundreds of herb species. Throughout the year Jaime and Paulina deal mainly in zacate limón, known in English as lemon-grass or citronella-grass, and naranjo agrio, or sour or Seville orange, which they cultivate and harvest themselves. They also sell most any other herb or plant product if they happen to stumble onto a good deal.

As soon as Jaime, Paulina, and I leave the Sonora's southern loading zone in their old truck, I begin seeing some of the business's realities: The loading zone attendant at the gate requires nearly a dollar for a parking fee. Then we tank up on gas.

"We make this trip almost every day," Jaime explains, peeling off small-denomination bills from a huge wad. The service-station attendant greets Jaime and Paulina by name, and seems to know all about their personal lives. The gas costs U.S. $14.67. I stand there remembering that a kilo (2.2 pounds) of zacate limón brings the family 33 cents, and, especially in the afternoons, sales as large as a kilo have been few and far in between. Each day Jaime must sell over 44 kilos (98 pounds) of zacate limón just to pay for the gasoline...

"Operating expenses just never end," Jaime begins to complain once we're cruising down Calzada Ignacio Zaragoza, heading southeastward out of town. "We had to pay U.S. $4,167 for our little stall in the Sonora, and of course we're still paying on that. If we had wanted a larger stall inside the building, it would have cost $13,333. We could have rented our little stall for $33 per week, or a big one inside for $133 per week, but we decided to do what we did. Besides this, we have to pay $12 federal taxes each month, and every day the police come around wanting a contribution of 33 cents. Since Paulina works with me and can't fix lunch for us, each day we pay three to six dollars for food. And I'm probably forgetting about lots of other expenses. Of course the old truck breaks down every now and then, and it's always needing new tires. We get up at 5 AM and work to about 6 PM every day, every day, seven days a week, and with that there's hardly ever enough money left to feed us."

"Trabajamos para comer," he says gloomily, paying a couple of bucks at the toll booth at the entrance of Mexico 190-D: "We work just to eat.

Cruising down 190-D, we pass another pickup heading out of town, loaded high with close-packed bales of herbs.

"It's almost a certainty that he's also coming from the Sonora," Jaime surmises proudly. "He's a wholesaler, probably going to Puebla where he'll resell the herbs at a little profit. There's just nowhere where you can get better deals in herbs than at the Sonora.

Moments later we pass yet another pickup truck loaded high with bales of herbs, heading in the opposite direction.

"He's heading to the Sonora, too, to sell his crop" Jaime laughs. "If you're a serious herb dealer in Mexico, you just have to deal with the Sonora."

Today we're going to harvest zacate de limón from a field Jaime and Paulina rent just south of Cuautla, Morelos, about seventy miles south- southwest of Mexico City. We take the first exit off 190-D and continue south on Mexico 115. The first couple of miles are flat and barren, but at Chalco the whole landscape tilts upward and the old pickup's engine starts straining.

As we climb, tall, slender pepper-trees with their gracefully hanging branches line both sides of the highway. All three of us feel cheerful and relieved being out of Mexico City's never ending noise and air pollution. We drive with the windows down, just gulping fresh, cool air. Having begun in Mexico City at an elevation of about 7,350 feet, at Amecameca we reach 8,102 feet. Behind Amecameca, to the east, the landscape slopes upward into a hazy sky, and we know that from here on rare clear days it's possible to glimpse the snow- capped volcanoes of Iztaccíhuatl (17,343 feet) and Popocatépetl (17,930 feet). Unfortunately, today, as usually is the case, Mexico City's famous smog completely obscures those majestic peaks.

At Ozumba we reach 8,200 feet and stop at the mercado to eat blue, salsa- drenched huaraches so hot that steam rises from them in the chilly air. The old woman who prepares them knows Jaime and Paulina by name, and she asks how Jaime's mother is doing. A torrential rain comes out of nowhere, and within a minute a raging, foot-deep river of brown water floods Ozumba's main street, stopping all traffic. The orange plastic tarpaulin above the huarache-lady's portable stove sags dangerously. She pokes at it with a broomstick, and the water cascades in a gigantic silver curtain that the wind blows onto us. However, no one but I seems to notice what is going on; they say nothing about the flood and keep eating their huaraches. Apparently such storms are completely normal for this mountain-crest village. Despite my resistance, Jaime insists on buying all our huaraches.

Jaime and Paulina live in the house of Jaime's parent's in Tepetlixpa, a couple of miles below Ozumba, and we need to stop there. Here Jaime reveals that we've come the whole distance from Mexico City with hardly any brakes at all, and that now since we're starting to descend to Cuautla, he needs to bleed his brakes and adjust them. We chug up an incredibly steep, one-lane cobblestone and mud street hemmed in by eight-foot-high adobe walls.

We park, pass through a small wooden door in the wall, and enter a very pleasant, well kept courtyard surrounded by low buildings painted blue and yellow. With so many flowering plants such as geraniums, impatiens, bougainvilleas, and heliconias blossoming in rusty metal cans, cracked glass jars, earthen pots, and from the ground, it feels like a botanical garden. Three canaries and a babbling little boy fill the air with happy sounds. The seventeen-year-old daughter and an older woman greet me graciously, and offer me a refresco to drink while Jaime works on his brakes.

It occurs to Paulina to show me some of the plants in their backyard. She shows me muicle, cedrón, ruda, neldo, altea, níspero, nogal, magnolia, and aguacate. Most of these plants' uses are described in the medicinal plants part of our produce section, but I have never heard of a couple of them, and can find their mention in no books.

When we return to the courtyard, a very old, bent-over, humbly dressed woman awaits us with an armload of muicle from her own backyard. Paulina pays her a few pesos and the old woman smiles warmly. Soon Jaime returns, apologizing for the delay. As we return to the road, I'm told some of the history of both Jaime and the old truck.

"During the first years after our marriage," he begins, "every day I'd harvest my zacate limón or naranjo agrio, bale it up and carry it to the bus stop with sweat running from under my arms. I'd take it to the Sonora and sell it. Doing it like that was expensive and took so much time, but that was the only way I had to make money, so I did it. Every day!"

"Years passed and finally I'd saved enough to think of buying a truck. Since I worked in agriculture, I got special papers from the government allowing me to import a pickup from the U.S. without paying import duties. Without that dispensation, I'd never have been able to buy it. When I got all my papers together, I took a bus to the frontier, crossed into Texas at Matamoros, and at Brownsville, Texas bought this old thing, a '75 Ford Custom. Now I can carry a lot more herbs, but my expenses are a lot more. We still have to live in my father's house, but at least I don't have to take the bus every day to Mexico City."

To prove the truck's gringo pedigree, Jaime points to a sticker on the cab's back window promoting the Oklahoma Farm Union. But Jaime has Mexicanized his old beauty by adding foot-high decals of cobras with spread hoods on his front fenders and, on the hood, a three-foot-wide decal of something looking like a bat with flaming wings. He's also added fog lights, extra parking lights and brake lights, and maybe some Christmas lights as well. This old truck has class.

In Cuautla, Paulina enters a pharmacy and phones a fellow who sometimes has albahaca, or basil, for sale. The man says he just happens to have several bales ready for someone else to carry to the Sonora, but he'd be glad for us to buy three or four. We find the house, the two-foot-thick bales are stacked in front, and in this unplanned, informal manner we begin accumulating our day's supply. As we're about to leave, the man asks if I want to buy marijuana.

"It's big business around here," he laughs, "everyone sells it, and it's good."

It's late afternoon when we finally drive into the valley holding Jaime's rented field of zacate limón. The flat fields with mountains rising all around are beautiful. We pass fields of corn, sugarcane, rice, beans, and gladiolus. Guava trees grow along the irrigation ditch our one- lane dirt road runs by. Sunlight slanting into the covered back of our pickup truck heats up the basil we've just bought, and our cab becomes charged with this powerful, salady scent. We are in a wonderful mood and when we see an old man who has stolen sweet-corn from a cornfield, and is roasting the ears over a fire that's more smoke than heat, we all laugh like kids.

Jaime's 3-3/4-acre field of zacate limón, which costs him $667 a year to rent, took fifteen days to plant, two years ago. Zacate limón is a large, lemony-tasting grass reproducing by small tubers. Once the plant is mature, its several tubers can be separated and replanted. In such a way, Jaime dreams of enlarging his acreage year after year.

"Someday Paulina and I will have our own home," Jaime predicts.

Jaime bends over each clump of grass, gathers the loose blades with his left hand and then with a special curved machete shears the blades about six inches above the ground. He removes the most conspicuous brown blades, then deposits the green ones in a pile next to the kneeling Paulina, who patiently arranges the material into neat hands. It's tedious but not unpleasant work. An odor like lemon meringue pie suffuses the late-afternoon air. Orioles, red-winged blackbirds, and great-tailed grackles sing from trees along the irrigation canal, and small frogs croak lustily from silvery rain-puddles in the field. It's a magic moment, peaceful and perfect.

Later, as Jaime arranges his harvest in the back of the old Ford, Paulina goes collecting toloache, or jimsonweed, from a neighboring field. She says the juice is good for pimples.

"Yeah, and if you put juice from its stem and roots onto a fellow's food, it'll make him go crazy," laughs Jaime.

We're ready to drive away, but Paulina insists on rushing to some guava trees and pulling off some leaves.

"Good for stomach pains, colic, and diarrhea," she says dead-pan, climbing back into the truck.

As we head back toward Cuautla, I ask Paulina where she learned all her information.

"When I was a child," she says, "I accompanied my grandmother when she went collecting medicinal herbs, which she sold in the mercado. But I didn't pay any attention at all to what she was doing, so I didn't learn a single thing from her. Then when I married Jaime and I started selling herbs, I saw that I needed to know these things, so I got books and started reading."

Her main book is an old classic that gets reprinted from time to time, Las Plantas Medicinales de México, by Maximino Martínez.

Returning through Cuautla, it's already almost night, but Paulina decides to call a certain family that a while back mentioned to her that they grow basil. She calls and we're invited to go pick the family up, carry them to their field out of town, and they'll pick a few bales as we wait. We're all tired, but we do this.

On the way to the family's field, as we bounce down a very weedy, one-lane, dirt road between fields, something unexpected happens. A beautiful black and white sheep of a large, slender, muscular pedigree is standing in the middle of the road, and it doesn't budge as we approach. Jaime stops, blows his horn, but the sheep just stands there. Jaime inches the old Ford forward to nudge it. The sheep is hidden below the hood, but surely it's gotten out of the way by now, so Jaime continues very slowly, constantly looking right and left for the sheep, but it's just gone, obviously having darted into the roadside weeds. We speed up a bit, and then a man sticks his head from the hedgerow before us, a horrified look spreads across his face, and he starts screaming. Jaime slams on the brakes, understands that the sheep is under the truck, and backs back.

The sheep lies there not making a sound, looking as if it's peacefully digesting a recent meal, but unable to get up. One of its shoulders is dislocated and a whole leg sticks out crookedly. The man is very upset. He and Jaime debate whose fault it is when a sheep that is too dumb to get out of the way is allowed to wander loose on a public road and gets run over. As the argument proceeds, the family in the back of the truck piles out and heads to the field to begin work.

The debate goes on and on. The man wants U.S. $100, but Jaime says that that's impossible. With a sense that the debate is unfinished, we return to the truck and continue to the field.

Sometime later the man arrives with a friend and the debate continues. When it's fully dark and the family comes in the moonlight carrying bales of basil on their heads, finally Jaime agrees to buy the sheep. But he'll have to come back later with the cash because he doesn't have it now, and he'll have to talk to a veterinarian friend before he decides how much he'll pay. The basil family knows the sheep man and vouches for Jaime's honesty; but the mother of the family tells the sheep man that he should be ashamed for expecting to be paid for a loss he brought upon himself by not properly watching his sheep.

Eventually Jaime pays the man a hard-earned $50, and a several-day feast of mutton follows.