OAKLAND, Calif. --Jeremy Ramsay leads me through the back corridor of the nondescript one-story building that is Harborside Health Center. His bright little office is windowless but cheery, its white walls reflecting the glow of fluorescent lights, banks of them. Layer on layer of shop lights are feeding dozens -- hundreds -- of six-inch rooted cuttings of marijuana.

Ramsay is manager, clones, a title straight out of "Brave New World." His babies are weeks away from bulking up and setting the bizarre clusters of mind-altering flower buds, but even in youth the lobed leaves, slender and saw-toothed, are distinctive, iconic, ominous.

If your last joint was experienced while coughing along to a Bob Dylan album in the '70s, Ramsay's offerings will seem incredibly far out. I mean, incredibly.

On the other side of the building, patrons are spoiled by a choice of varieties whose pothead names are lagging behind the contemporary, therapeutic image of marijuana -- sorry, cannabis -- in all its boutique wonder. Kushage bestows a high helpful for brainstorming. Sour Cream is so calming. Kish is fruity but potent. Martian Mean Green flowers up a stench, but the buds burn real stoney.

I have come to California to see a quasi-underground horticultural marvel: growers, breeders and dispensers who have quietly brought the hemp plant to a level not seen in its rocky 6,500-year history with humankind.

When alcohol was chased underground during Prohibition, the resulting clandestine booze was notoriously rank -- the paint-stripping moonshine, the barely drinkable homemade wine. Marijuana, however, has undergone radical advances since the war on drugs sent it deep into the shadows 25 years ago.

In the now semi-open marijuana landscape of Northern California, I find a plant species transformed. Skilled mom-and-pop breeders have developed hundreds of high-performing cultivated varieties, and home hobbyists have grown them to perfection using new techniques and technologies. Marijuana has never been more potent, more productive and more varied in its appearance, flavor and effect. It is twice as productive as in the 1980s and three or more times as potent. As the supply has increased, the value has dropped or stagnated, from $5,000 a pound 15 years ago to about $3,000 today. By the ounce, Ramsay says, the choicest varieties still sell for as much as $400, but the cannabis connoisseur can pick up high-grade strains for half that amount today.

Many Americans of a certain age will remember that in the 1970s, seedy homegrown pot was reviled for its raw, throat-burning quality. Now dope-smoking locavores steer clear of cheap, low- and mid-grade weed in favor of organically grown boutique strains. They speak of "presentation" and varieties so agreeably complex that "you inhale one flavor and exhale another." Just as in the vineyards of the Napa Valley a few miles to the north, complexities come from the soil, from the fruits of labor, from careful breeding. Suddenly, pot has terroir.

It's surreal, even for California, but it may be our future.

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Fourteen years after Californians approved medical marijuana, they return on Tuesday to consider Proposition 19. This would allow people 21 or older to become the first in the nation to legally cultivate, possess and use small amounts of marijuana, and let local governments license commercial growers and retailers.

If it doesn't pass, its backers vow to return. If it does pass, California will become even more cannabis-friendly than the Netherlands.