GLENDORA >> This is not your ordinary super bloom.

Thousands of rare, blue-lavender flowers poking through the wild grasses in the foothills of the San Gabriel Mountains are throwing a blooming party all their own.

They’re called Brodiaea filifolia, one of the most endangered plants in Southern California. In fact, the three hillsides above Glendora are the only places anyone can view these flowers, aside from a preserve in Riverside County and in a few coastal canyons in southern Orange County, according to state and federal environmental agencies.

“This is the last place in Los Angeles County where they exist. And they are flourishing at super-bloom status,” said Ann Croissant, a plant physiologist, botanist, professor emeritus from Azusa Pacific University and the founder and president of the Glendora Community Conservancy.

Listed as endangered by the state of California and threatened under the federal Endangered Species Act, the shy plant that stopped a housing project in 1989 and sparked a community conservancy movement in this conservative town is now in the midst of the largest bloom in modern times.

When the Conservancy began buying land to preserve plant and animal species in the hills above Glendora and Azusa, it purchased property known as the Colby Trail at the top of Loraine Avenue in eastern Glendora. On a meadow badly damaged by agricultural activity, botanists counted 900 plants in 1993. That grew to 6,900 plants in 2012 and about 8,500 today, Croissant estimates.

“They are spectacular. It’s just incredible what’s going on even in the lower level of the Colby Trail,” she said. “This is the best bloom I’ve ever seen.”

The debutantes of the bloom ball being celebrated in Southern California this spring don’t display a blanket-like palette like the state flower, the orange-hued California poppy, as seen in record numbers in Hemet, Lancaster and Chino Hills.

Instead, the thread-leafed Brodiaea, as they are more commonly known, bunch in clusters of eight to 10, standing tall on thin, spindly, green stems, unfurling their star-like purple-striped flowers under the shade of an oak or amidst the shelter of the taller, beige-colored wild oat plants.

On Thursday, Croissant walked the lower meadow, explaining how the unusual plant deposits its seeds, known as corms, in the volcanic, clay soil during the winter unique to the Glendora hills. A bounty of rainfall grew the green leaves and stems, producing flowers three days before Earth Day, on April 19, she said.

“Here they come!” she exclaimed, pointing to a bunch in the middle of the tall wild oats. “They sneak up on you.”

Toward the south end of the 4-acre meadow, the bunches appeared more frequently.

“They look for a place to hide, like finding a companion plant,” she explained. That way they can be protected from ravenous deer. “They are survivors.”

Even the Colby Fire of January 2014 did not stop them. In fact, the ash from the fire helped enhance the soil, which helped the Brodiaea to germinate.

These Brodiaea filifolia in Glendora are the purest of the species, she said. They are pollinated by a bee fly, which keeps their DNA the same.

About 20,000 plants are thriving along the ridgeline above the Colby Trail. In Bluebird Canyon exist another 5,000 and about another 10,000 in another hillside canyon, she said.

The Colby Trail is open to the public during the daytime. Croissant reminds everyone to stay on the trails. “They are state and federally protected, so that means you could be arrested or cited for any kind of abuse to the plant,” she said.

The Glendora Conservancy is hosting a Brodiaea Month and is offering a special program on the plant on May 20 at the Glendora Library, with a lecture by Croissant and a video on the plant’s history. The plant is the city’s official flower.

Glendora is the only city in California with an endangered species as its city flower.