Wendy Leonard remembers the first time she discovered the bracted twistflower at Rancho Diana, a City of San Antonio-owned preserve in northwest Bexar County that’s not open to the public.
“The whole hillside was just lavender blue, blowing in the wind,” said Leonard, a nature preserve officer with the city’s Parks and Recreation Department. “It was gorgeous.”
The tall purple wildflower, a member of the mustard family whose distant cousins include broccoli and cabbage, once thrived across much of the Hill Country. But with its prime habitat now mostly located along the Interstate 35 corridor between San Antonio and Austin, the twistflower is threatened by rapid development, according to the U.S. Fish and Wildlife Service.
Hungry white-tailed deer and other herbivores also threaten the species, along with hikers and mountain bikers venturing off-trail on the few public lands where it’s been found growing in recent years.
On Tuesday, agency officials announced they’re proposing the bracted twistflower, Streptanthus bracteatus, for listing as threatened on the federal endangered species list. If approved, digging up, cutting, or otherwise harming the plant would be illegal. The decision could affect the use of a handful of private properties where the flower’s presence has been confirmed.
Chris Best, Texas botanist for Fish and Wildlife, said in a prepared statement that much of the flower’s range falls in “one of the fastest growing urban areas in the United States.”
“We estimate that 33% of the species habitats have been lost to urban and residential development of the last 30 years,” Best said. “The good news is that we have many dedicated local partners who are helping us protect and recover this species in the remaining occupied habitats.”
Designating the flower as “threatened” means it’s likely headed for extinction one day if trends don’t change. As the agency puts it, “an endangered species is in danger of extinction now, while a threatened species is not in danger of extinction now but is likely to become so in the foreseeable future.”
Since 1989, Fish and Wildlife has identified the flower growing on 17 properties in Uvalde, Medina, Bexar, Hays, and Travis counties. In that time, two of those populations were “completely destroyed,” with another four “partially destroyed.” The 11 other sites remain intact.
In Bexar County, the flower’s habitat include Rancho Diana, a 1,300-acre preserve, as well as Eisenhower Park, a 420-acre space that’s open for hiking. At Eisenhower and other public lands in Travis County where the flower is found — including the popular Mt. Bonnell and Bull Creek hiking areas — people who venture off-trail hurt the growing plants as well as the soil where its seeds are stored.
Leonard did her master’s thesis on the bracted twistflower while studying at the University of Texas at San Antonio. She “fell in love” with the plant because it evolved to live only in the Texas Hill Country. Figuring out what unique ecological ingredients caused it to evolve only here poses an interesting puzzle for a biologist.
“It starts off looking something like a dandelion out in your yard,” she said. “But in the springtime, it can be big and beautiful with purple blooms. … It’s just a gorgeous plant, but not many people have seen it.”
Scientists have been sleuthing out how to protect the plant for decades. Fish and Wildlife’s proposal document notes the efforts of the Bracted Twistflower Working Group, “a consortium of federal, state, and local agencies, researchers, and conservation organizations,” including the City of San Antonio, that has met informally since 2000.
Leonard said the most effective measures to preserve the plants involve installing fencing to keep out deer, who find the plant “very tasty.” Cutting back the trees and woody shrubs that cast too much shade is also a must, she said.
If the flower makes it on the endangered list, Leonard doesn’t think the decision will significantly affect the how the city manages Rancho Diana or Eisenhower Park. However, it could have implications on some private lands where the flower’s been found, including in Uvalde and Medina counties west of San Antonio.
Harming the flower — say, by paving over a patch of land where it’s growing — wouldn’t be legal without a permit fro Fish and Wildlife. Critics often decry this permitting process as expensive, time-consuming, and difficult to navigate.
But “the goal of this process is to restore listed species to a point where they are secure, self- sustaining, and functioning components of their ecosystems,” the agency’s document states. One recent success story is the black-capped vireo, a songbird that was taken off the list in 2018 thanks to conservation efforts.
Leonard said the flower’s population could be restored enough to remove it from the list eventually, but it will take work.
“If we can get a couple of these remaining populations managed well, then we’ll increase the individuals in those populations,” she said. “But there are so few of those populations left, I don’t think it could be delisted without introducing new populations and suitable habitat.”