Helanthus debilis is a species of sunflower native to the gulf and Atlantic coasts of the U.S. There are five recognized subspecies with more limited ranges. One of these is H. debilis subsp. vestitus, the hairy beach sunflower. Hairy beach sunflower is a Florida endemic that is listed as imperiled and found only on the beach dunes of southwest Florida.
The Center for Plant Conservation subcontracted the Rare Plant Conservation Program (RPCP) to collect and preserve seeds of this subspecies in 2024 because it is fast disappearing in the wild. In addition to the continuing threats to the dune habitat such as development and erosion, a bit part of the reason this subspecies is in need of preservation, is that many cultivars and other species are common in the nursery trade and widely planted as ornamentals in coastal settings.
The cultivars can easily cross pollinate with the hairy beach sunflower and eliminate a true population by causing seedlings to be hybrids. The RPCP selected a population at Siesta Key threatened by hybridization and beach disturbance. Working closely with the Conservation Foundation of the Gulf Coast, seed heads were collected from roughly 50 maternal parent plants, and brought back to the Gardens. In a tedious process that is expected to take several weeks, seeds are currently being carefully removed from each head, counted, and kept separate by maternal line.
Microscopic examination has revealed that many of the seeds are empty or have been damaged by insect predators. In upcoming weeks, a germination trial will be set up on some of the seeds, so we can learn what percentage of seeds are viable. The rest of the seeds will be placed into long-term cold storage so this unique subspecies will be safely preserved, and the stored seeds can also be used as a source of plants that can help augment other threatened populations or to introduce new populations.
Article by Cheryl Peterson, Conservation Program Manager at Bok Tower Gardens.