 |
Vegetative E. decumbens in the greenhouse |
The Willamette daisy (
Erigeron decumbens var.
decumbens) is an herbaceous perennial in the Asteraceae family that is endemic
to Oregon’s Willamette Valley.
Although
it was once common throughout wet prairies and upland meadows in the region,
habitat degradation and fragmentation has caused a severe decline in population
numbers.
There are currently fewer than 40 known populations of Willamette daisy in existence, a quarter of which cover less than one acre.
This is concerning due to
the loss of genetic diversity, which results in inbreeding depression within
populations.
The decline was
severe enough to warrant protective listing by both state (Oregon
Department of Agriculture) and federal (US Fish and Wildlife Service) agencies,
as well as federal designation of critical habitat. The Willamette daisy can be identified by its tall,
pink to purple flower and its slender, lanceolate
leaves that turn glaucous in the spring.
The genus name
Erigeron is
derived from the Latin words
eri-
(meaning early) and -
geron (meaning
old man).
The name describes
the grey-green coloring that the leaves
develop in spring before the flowers bloom in June and July.
In its vegetative state,
E. decumbens can be confused with
Plantago sp. but can be correctly identified by the three parallel
veins running up the leaves.
 |
Willamette daisy capitula |
The Institute for Applied Ecology has undertaken several
experiments to identify the threats to the populations, as well as management
techniques and reintroduction methods that could prove
beneficial to species recovery.
Recovery prospects are poor without intervention, so it is important to
establish effective reintroduction and management strategies. IAE initiated experiments in 1999
focusing on determining ideal habitats for reintroduction efforts.
Seeds were collected from populations in both
wet and dry habitats and redistributed in experimental plots that were
classified as wet, intermediate, and dry habitat.
Seeds from both source habitats fared equally
in the introduction plots, indicating that there isn’t a specific habitat type
that would be more suitable than others for seeding projects.
 |
Eugene fire crew burns a treatment plot near Fern Ridge |
Another round of experiments is currently being conducted to
determine the best management practices for
E. decumbens populations.
Threats that must be managed include encroachment
of shrubby and woody species and invasion by non-native forbs and
grasses. Initial experiments tested the effects of the common management
activities of mowing, grazing, and burning, but in 2011 additional treatment plots were created to test other options such as carbon addition (pouring sugar on plots),
use of grass specific herbicide, and application of glyphosate. An additional set of treatment plots has been established this year to increase data collection locations. IAE has grown over 1800
E. decumbens individuals that will be outplanted this month. Propagation of this species required allowing 16 weeks of cold stratification in germination boxes, followed by one week in greenhouse conditions before the seeds were carefully transplanted into containers and tended to in the greenhouse for several months. Although the process is intensive, IAE has been very successful at growing robust plants for use in experiments.
 |
(L) Seeds in germination boxes, (R) Plants growing in greenhouse |