It was dumb luck that paired Barbara Melera and Michael Twitty. After the two separately attended an event at Monticello, the historic home of Thomas Jefferson, Mr. Twitty needed a ride back to Washington, D.C., and ended up in Mrs. Melera's car.

She is president of D.Landreth Seed Co., the oldest seed house in the country. Mrs. Melera left the world of venture capitalists to take over the struggling company in 2003. As she sat in the company's old office trying to decide whether she should purchase it, Mrs. Melera began to look at some of the company's artifacts.

"I started going though this old cardboard box of books, and it contained original catalogs back to 1839. I just looked at it and thought, 'Oh my God, this is the history of American horticulture sitting in this box.' "

The nostalgia that reeled her in persists. She has used skills learned from her former career to improve the company, even as interest in starting from seed was waning among gardeners.

"I was trying to think of a way to communicate with people to encourage their interest in seeds," she said. "Maybe the way to do this was to organize themed collections around things that people were interested in."

First was a collection for container planting, then kids and an informal Italian seed collection.

Back then the company was in Baltimore, which has a large African-American population, and she noticed a lack of interest in gardening. The same was true as she traveled the country visiting flower shows; she rarely saw people of color.

"Yet their heritage is American horticulture," she said. "I got to thinking this is something they should be really be proud of and brag about, talk about and know about. This is real culture, this is their culture."

The idea of a collection of African-American seeds was floating around in her head when Mr. Twitty climbed into the backseat of her car. He introduced himself as a culinary historian who focused on African-American food culture. The die was cast and on the drive from Charlottesville, Va., to D.C., the African-American Heritage Collection was born.

It's an eclectic group of more than 30 varieties, all grown by black slaves.

'Burgundy Okra' is not only edible but beautiful, too. The plant is an intense shade of purple, with creamy white hibiscus-like blooms.

One of Mrs. Melera's favorites is 'Red Malabar Spinach.' Although it's not really spinach, the nutrition value is close, and it thrives in hot weather. The red vines can grow to 20 feet long with heart-shaped leaves that stay tender all summer and taste like its namesake.

But the cushaw brings real excitement to her voice. Both 'Green Striped' and 'White' cushaws make great pie and soup pumpkins, and their veins are tinged with silver.

"In the early morning light, that silver just shimmers, especially when they've been bathed in dew," she said.

The company is now based in New Freedom, York County, and the African-American Heritage Collection has been a huge hit "because it's real," according to Mrs. Melera.

"These people really did eat these foods, raised these plants. ... This is who they were, what we did, and people are starved for that kind of knowledge."

Mr. Twitty's love of plants and their history is partly rooted in the gardens his grandparents grew.

"It's kind of one solid line between myself and them," he said.

The 32-year-old historian from Rockville, Md., researched what the slaves ate and grew in their own gardens. Narratives from slaves, interviews, seed catalogs, travelers' accounts along with other writings and archaeological evidence all played a role.

Many slaves had their own little patch of garden, which was often worked during off hours, on Sundays, or by children and elders.

"These gardens are really important because you begin to realize this was their self-respect, their self-control, their personal sense of power. They really felt a sense of sincere ownership over these plots," he says.

The seeds the slaves grew probably weren't brought with them from Africa, even though Mr. Twitty says every black culture has the same myth: that some seeds were concealed in hair or ears. He says the seeds came from missionaries, traders, botanists and others. Food brought on the journey from Africa, like sorghum or black-eyed peas, also contained seeds that would be saved for planting.

Mr. Twitty, who is an avid gardener himself, says few Americans have a relationship with the land as their ancestors did.

"In less than a century, we went from being 90 percent rural people to 90 percent urban people," he says.

"Plants really unify us in our human experience. We had to engage with them to become civilized," he said.

It may bring more African-Americans and other people of color to gardening. But it's also going to make our tradition that much more universal. It will give people an opportunity to see how we became Americans and what we contributed to America."

The D. Landreth Seed catalog is sold out, but there's innovative software at www.landrethseeds.com that allows visitors to read the catalog as if it was right in front of you. Just click "Request a Catalog." All the varieties, including the African-American Heritage Collection, are also listed at the website; for information, 1-800-654-2407.

Doug Oster writes a blog, "Growing With Doug," exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.