The following Participating Institutions are custodians for this species in the CPC National Collection:
Rae Selling Berry Seed Bank & Plant Conservation Programs
Cincinnati Zoo & Botanical Garden
The conservation of Aster vialis is partially sponsored.
Edward Guerrant, Ph.D. contributed to this Plant Profile.
Like so many other species, wayside aster is fighting an uphill battle to survive. To add insult to injury, it is not even a very attractive plant. Wayside aster lacks the showy, petal-like "ray flowers" that help many recognize other asters. This understated flower is threatened by habitat changes within its limited range in and around Oregon's Willamette Valley, and is in danger of quietly disappearing. Seedling recruitment appears nonexistent in some populations, a grave sign of its uncertain future.
Wayside aster's reproductive biology and habitat requirements make it especially vulnerable in human altered ecosystems. While many plant species self-pollinate, Aster vialis require pollen from other individuals in order to produce seeds. Increasing forest fragmentation makes obtaining pollen more difficult as great distances often separate plants. Even after this distance barrier is overcome, seed set is low. Experimental hand pollinations in the greenhouse typically produce few seeds. Additionally, germination rates are often extremely low in laboratory conditions. These low germination rates likely reflect that specific conditions, such as light and an absence of leaf litter, are necessary in order to break dormancy.
Vigorous and reproductive Aster vialis plants are found in habitats that receive abundant light. Fire historically played a large role in maintaining open understory habitats in and around the Willamette Valley. As opposed to the clear-cut or regeneration forest harvest methods used today, fire historically did not result in the death of all the trees in the stand. Larger fire tolerant trees such as Douglas fir and ponderosa pine often survived and provided some shade. Natural regeneration after a fire is patchy, resulting in forest gaps that provided habitat with high light levels suitable for wayside aster. Fire also burns away leaf litter, creating conditions thought necessary for germination by exposing the ground to sunlight and returning nutrients to the soil. In pre-settlement Oregon, wayside aster most likely did not persist in specific locations over long periods of time, but new populations were continually established as new habitats were created by natural disturbances. Under land-use practices today, this regeneration cycle is made more difficult due to a lack of available habitat.
Distribution & Occurrence
Found in woodlands on mineral soil with little leaf litter, between 500-1500 ft (150-460 m) elevation (Meinke 1982)
Associated species include Pseudotsuga menziesii, Castanopsis chrysophylla, and Arbutus menziesii (Meinke 1982)
|As of 2001: 81 known sites; a few large populations exist, but most populations contain fewer than 100 stems.|
Conservation, Ecology & Research
Aster vialis is completely self-sterile and has extremely low viable seed set even when outcrossed (Kaye et al. 1991). Seed set under experimental out-crossed conditions was 21% (crossed within population) and 29% (crossed between populations) (Kaye 1991). Pollination is facilitated by Bombus vosnesnski (a bumblebee), Lasioglossum spp. (smaller bees), Epicanta puncticollis (blister beetle), and Ochlodes (skipper) (Alverson and Kuykendall 1989 in Wogen 1998).
The low viable seed set may result from inbreeding depression. Genetic analysis revealed low mean genetic variation within populations and intermediate genetic variation between populations. A lack of correspondence between genetic differentiation and the geographic locations of among Aster vialis could be due to fragmentation, restricted gene flow between distinct populations, genetic bottlenecks and fixation within small populations, and error in sampling plants and genetic loci. There was no evidence of genetic distinctness of southern populations, but the recently identified populations in the Siskiyou Range may be more distinct. This discovery extends the geographic range of the taxon and suggests that cryptic populations may exist throughout its range.
Habitat fragmentation leading to decreased pollen flow and inbreeding depression. (Kaye et al. 1991 and Wogen 1998).
Fire suppression, which leads to excessive understory br
In vitro germination procedures developed by CREW (Center for Reproduction of Endangered Wildlife) at the Cincinnati Zoo and Botanical Garden (BBG File).
Breeding system experiments utilizing different pollination treatments demonstrated that Aster vialis is completely self-sterile (Kaye et al. 1991)
Study of seed structure (Florance 1994).
Germination trials. Embryos were excised (removed from the seed coat and endosperm sac), and then treated with solutions of varying pH. Slightly basic solutions led to development of the embryos, suggesting that pH may have a major effect on breaking seed dormancy. In the wild, events such as fire that affect soil pH may be important in seed germination and population maintenance (Florance 1994)
Germination trials conducted at The Berry Botanic Garden. Initial results indicated very low germination (about 3%). A 50C heat treatment increased germination to ~15%, indicating that heat treatment helps break seed dormancy (Guerrant 1991)
Germination trials. After 8 weeks of cold stratification, 60-80% of seeds germinated in constant 20C or alternating 20/10C. When embryos were excised (removed from the seed coat) and then subjected to 8 weeks of cold stratification, 100% germination was obtained with either constant 20C or alternating 10/20C temperatures (BBG File).
Researchers investigated the levels of genetic diversity within and among populations, clonal-spread, and geographic components of genetic variation for populations in the Eugene and Roseburg BLM Districts. Mean genetic diversity in Aster vialis was found to be lower that that of other plants investigated using the same ISSR protocol. Putative clones were identified within several populations by shared haplotypes, and patterns of presence and absence of loci. However, some haplotypes were shared between disjunct populations, indicating that ISSR haplotype analysis may underestimate genetic variation. Estimated among population differentiation from allele frequencies was intermediate, and the greatest variation was contained within populations. Patterns of genetic differentiation did not generally match spatial distribution (Erhart and Liston 2001).
Aster vialis falls under the jurisdiction of The Northwest Forest Plan where it has been identified as a species associated with late-successional and old-growth forests. It also has BLM Special Status Plant Species designation and is classified as a BLM Sensitive species.
The Eugene District BLM initiated monitoring in 1989. Results from this monitoring however, reveal few trends in population numbers.
A multi-agency and organization proposal to determine the response of Aster vialis to habitat modification at several sites in the Eugene District, and subsequent improvement of potential habitat has been developed.
Seed from at least 13 populations collected and stored at the Berry Botanic Garden.
Determine how seed predation and browsing impact reproduction (Wogen 1998)
Determine ecological and habitat requirements, especially for promoting and maintaining seedling recruitment and flowering. (Kaye et al. 1991 and Wogen 1998)
Remove leaf litter and canopy shade through periodic burning. (Wogen 1998)
Genetic studies using co-dominant markers, such as microsatellites, to show true allelic heterozygosity and parentage within populations (Erhart and Liston 2001).
Determine mechanisms that limit genetic diversity within populations (Erhart and Liston 2001).
Maintain and protect as many of the known sites as possible due to potential inbreeding depression when pollen flow is restricted to a single site (Kuykendall 1991).
Determine the effect of habitat fragmentation and extent of inbreeding depression. Study the impact of pollination reduction (Kaye et al. 1991 and Wogen 1998)
Further investigate the roll of pH in seed germination (Florance 1994).
Determine optimum propagation and reintroduction methods.
Abrams, L.; Ferris, R.S. 1960. Bignonias to Sunflowers. Illustrated Flora of the Pacific States. 732p.
Meinke, R.J. 1982. Threatened and Endangered Vascular Plants of Oregon: An Illustrated Guide. Portland, Oregon: U.S. Fish & Wildlife Service, Region 1. 326p.
Porsild, A.E.; Cody, W. 1980. Vascular Plants of the Continental Northwest Territories Canada. 102p.