SEED CONSERVATION OF RARE PLANTS IN COLORADO

By Alex Seglias

Picture Colorado. What comes to mind? For most people, it’s the soaring, majestic peaks of the Rocky Mountains. However, the alpine ecosystem constitutes just one of Colorado’s six major vegetation zones. The state’s rich floral diversity is distributed throughout multiple systems, including shortgrass steppe, shrub steppe, pinon-juniper woodland, montane forest, subalpine forest, and alpine. Of Colorado’s 2,797 native plant species, 525 (16%) are rare, and 90 (2.6%) are rare endemics (see all rare Colorado species here). All of these taxa are at risk of decline as a result of multiple, interacting factors. Alpine species are particularly vulnerable to climate change, as temperature fluctuations are projected to be most severe in high elevation areas, and species will be displaced to higher and higher altitudes, or highly restricted microsites, until there is nowhere else to go. Additionally, large swathes of Colorado land are at risk of wildfires, urban expansion, and invasive species, threatening the native plants across the state.

Figure 1. Ecosystems found throughout Colorado. Top: Montane forest; Middle: Semi-desert shrublands; Bottom: Sagebrush shrubland.

Figure 1. Ecosystems found throughout Colorado. Top: Montane forest; Middle: Semi-desert shrublands; Bottom: Sagebrush shrubland.

Regional Plant Conservation Partnerships

There are many organizations working on plant conservation within the state of Colorado, from large federal organizations to smaller NGOs and non-profit groups. The Research and Conservation Department at Denver Botanic Gardens partners with the Center for Plant Conservation and the Colorado Rare Plant Initiative to monitor and collect seed from about 70 rare plant species across Colorado. As part of the Rare Plant Strategy, seed is collected to protect species through ex situ conservation. After collection, seeds are distributed among three main initiatives: 1) propagation by our horticulturists to be included in the Gardens living collections; 2) storage in a seed bank at the National Laboratory for Genetic Resource Preservation in Fort Collins, Colorado; and 3) germination research at Denver Botanic Gardens. One collection may be involved in just one of these actions, or all three. To date, we have completed germination research on 13 of our stewarded species. The primary goal of our germination research is to determine successful germination protocols, which are currently undefined for many Colorado rare species. Our goal for the next five years is to complete germination work on 25% of the species we have seed banked, both to determine germination protocols and to understand species responses to climate change.

2017 Field Work

During the past summer, we scouted for multiple populations of 10 rare species, and were able to collect seed from populations of three – Penstemon penlandii (Fig 2A), Phacelia gina-glenneae (Fig 2B), and Physaria bellii (Fig 2C).

Figure 2. Species scouted and collected in 2017. Left to right, top row: Saussurea weberi, Ipomopsis globularis, Aletes humilis, Penstemon degeneri. Middle row: Phacelia gina-glenneae, Penstemon penlandii, Astragalus osterhoutii. Bottom row: Physaria bellii, Aquilegia chrysantha var. rydbergii, Mirabilis rotundifolia.

Figure 2. Species scouted and collected in 2017. Left to right, top row: Saussurea weberi, Ipomopsis globularis, Aletes humilis, Penstemon degeneri. Middle row: Phacelia gina-glenneae, Penstemon penlandii, Astragalus osterhoutii. Bottom row: Physaria bellii, Aquilegia chrysantha var. rydbergii, Mirabilis rotundifolia.

Penstemon penlandii (Fig 2A) is known from only two locations in the world, separated by less than two miles. Seed has been collected six times from one of the populations, whereas the other population had not been assessed for many years. In 2015, the landowner granted permission for Denver Botanic Gardens scientists to take tissue samples for a genetic analysis. From the analysis, Gardens researchers discovered that the two populations are genetically distinct (in preparation for publication) (Fig 3). With these results, we determined that it was necessary to collect seed from the northern population for ex situ conservation, to capture as much of the genetic diversity as possible. In August 2017, we surveyed the previously unsampled population and were able to collect seed from 142 individuals. We are continuing to collect seed and perform research on this species to ensure adequate conservation, both through seed banking and living collections at Denver Botanic Gardens.

Figure 3. Approximate locations of the only two known populations of Penstemon penlandii.

Figure 3. Approximate locations of the only two known populations of Penstemon penlandii.

Phacelia gina-glenneae (Fig 2B) is a recently described new species. Gina Glenne, a U.S. Fish and Wildlife Service botanist in Colorado, identified it as a morphologically-distinct species from other Phacelia species found in northern Colorado and Wyoming, such as Phacelia formosula. Genetic testing further confirmed P. gina-glenneae as a distinct species (results in prep for publication), and it is known from only one location in the world. Denver Botanic Gardens just recently nominated this species for inclusion in the Center for Plant Conservation National Collection, and it was accepted.

With all three of the collections this year, we were able to increase the genetic diversity of our currently held seed collections.

The seed conservation program at the Denver Botanic Gardens has grown quickly in recent years and will continue to develop in the coming years. Our goals are to expand our seed collections, with the hope of collecting 25% of native Colorado flora and 30% of G1 and G2 species, and to expand our germination research to understand how species will respond to a changing climate. Additionally, we plan to initiate plant tissue culture research, to effectively preserve plant species, which cannot be conserved through traditional seed banking. Candidate species include those from alpine regions that cannot survive extended periods of seed bank storage, rare species that typically have low seed set, and species that do not reproduce through seed.  


Alex Seglias is the Seed Conservation Research Assistant at Denver Botanic Gardens. Her work focuses on seed collection for ex situ conservation and research on climatic effects on dormancy and germination. Email: alexandra.seglias@botanicgardens.org. https://alexseglias.wordpress.com/