Dwarf yellow fleabane (Erigeron chrysopsidis)

Nomenclature

Erigeron chrysopsidis A. Gray is commonly referred to as dwarf yellow fleabane. This species belongs to the Disparipili section, Conyzinae subtribe, Astereae tribe within the Asteraceae family (Nesom 2008). Nomenclature for subtaxa and synonyms follows Nesom (1992a; 2006).

Family

Asteraceae – Aster family

Genus

Erigeron

Species

chrysopsidis

NRCS Plant Code

ERCH4 (USDA NRCS 2017).

Subtaxa

Erigeron chrysopsidis A. Gray var. austinieae (Greene) G.L. Nesom, E. c. var. brevifolius Piper, and E. c. var. chrysopsidis.

Synonyms

Chrysopsis hirtella DC, E. austiniae Greene, E. chrysopsidis subsp. austiniae (Greene) Cronquist.

Common Names

Dwarf yellow fleabane and golden daisy (Nesom 2006; Rhodes et al. 2010).

Chromosome Number

Chromosome number is 2n = 18 (Solbrig et al. 1969; Cronquist et al. 1994; Nesom 2006)

Hybridization

Intermediates between varieties austiniae and chrysopsidis are found in northern Malheur County, Oregon, and northwestern Owyhee County, Idaho, where their ranges overlap (Nesom 1992a, 2006). Intergrading also occurs between varieties brevifolius and chrysopsidis, but rarely, as their populations only overlap near 6,000 ft (1,800 m) elevation in the Wallowa Mountains of the same county in Oregon (Nesom 1992a).

Distribution

Dwarf yellow fleabane frequently occurs in Washington, Oregon, California, Idaho, and Nevada (Fig. 1; Nesom 1992a, 2006). Variety austiniae is the most widely distributed, occurring in southeastern Oregon, northeastern California, southwestern Idaho, and in Elko, Eureka, Humbolt, and Washoe counties in Nevada (Nesom 1992b). Variety chrysopsidis occurs at mid- to low-elevation sites from southeastern Washington to southeastern Oregon (Nesom 1992a; Hitchcock and Cronquist 2018). Variety brevifolius is restricted to upper elevation sites in the Wallowa Mountains in the northeastern corner of Oregon (Nesom 1992a, 2006). Because of its limited distribution, variety brevifolius is considered a conservation concern (Nesom 2006).

Figure 1. Distribution of dwarf yellow fleabane varieties and a relative, Piper’s fleabane (Erigeron piperianus). Figure from (Nesom 1992a).

Habitat And Plant Associations

Dwarf yellow fleabane occupies dry, gravelly and rocky, open sites often with bunchgrasses (Idaho fescue [Festuca idahoensis], bluebunch wheatgrass [Pseudoroegneria spicata]) and sagebrush (Artemisia spp.), but it is also associated with juniper (Juniperus spp.), ponderosa pine (Pinus ponderosa), and alpine communities (Leckenby and Toweill 1983; Cronquist et al. 1994; Nesom 2006). Varieties austiniae and chrysopsidis are typically associated with dry, lower elevation communities of sagebrush and juniper, whereas variety breviolius is associated with rocky slopes and cliffs of alpine slopes and summits (Nesom 2006).

Dwarf yellow fleabane occurs on shallow, rocky basalt soils in the Zumwalt Prairie in Wallowa County, Oregon, which occupies elevations of 3,490 to 5,510 ft (1,060–1,680 m). Winters there are cold and moist; summers are very warm and dry; and annual precipitation averages about 19 in (490 mm) (Bartuszevige et al. 2012). In south-central Oregon, dwarf yellow fleabane is common in western juniper/mountain big sagebrush (J. occidentalis/A. tridentata subsp. vaseyana) communities (Leckenby and Toweill 1983). In the Blue and Ochoco mountains of eastern Oregon, fleabanes (Erigeron spp.) are frequent in the understory of curl-leaf mountain mahogany (Cercocarpus ledifolius), antelope bitterbrush (Purshia tridentata)-big sagebrush (A. tridentata), mountain big sagebrush, and low sagebrush (A. arbuscula) shrublands and ponderosa pine/antelope bitterbrush woodlands (Johnson and Swanson 2005). In northeastern Nevada, dwarf yellow fleabane was reported as occurring in the seedbanks of 2 of 17 big sagebrush sites and in the aboveground vegetation of 3 of 17 sites (Barga and Leger 2018).

Elevation

The species ranges from elevations of 2,600 to 8,500 ft (800–2,600 m) (Cronquist et al. 1994; Nesom 2006). Variety austiniae occurs at elevations of 3,900 to 6,600 ft (1,200–2,000 m). The elevation range of variety brevifolius is 5,900 to 10,500 ft (1,800–2,300 m) and variety chrysopsidis is 2,600 to 8,500 ft (800–2,600 m) (Nesom 1992a, 2006).

Figure 2. Dwarf yellow fleabane growing in sagebrush habitat in Oregon. Photo: USDI BLM OR030 Seeds of Success (SOS).

Description

Dwarf yellow fleabane is a perennial forb with a slender taproot and short, branched caudex. Stems are often erect, 1 to 6 in (3–15 cm) tall with long spreading hairs or short hairs (Cronquist 1947; Cronquist et al. 1994; Nesom 2006; Hitchcock and Cronquist 2018). All or most leaves are in basal tufts, or there may be a few reduced stem leaves (Cronquist 1947; Cronquist et al. 1994; Nesom 2006). Leaves are entire, narrow and linear, and up to 3.5 in (9 cm) long and 3 mm wide (Cronquist 1947; Nesom 2006). Leaves are often very hairy with spreading hairs of mixed of uniform lengths (Cronquist et al. 1994). The bases of lower leaves are often enlarged and whitish (Cronquist 1947; Nesom 2006). Plants produce just one flower head per stem. Flower heads are comprised of both yellow ray and disk florets, but ray flowers may or may not have ligules (Cronquist 1947; Nesom 2006). Involucres typically measure 4 to 7.5 mm high and 0.9 to 1.7 mm wide (Cronquist 1947; Nesom 2006). Disk florets are bisexual and fertile. Flower heads contain 20 to 60 ray florets, which are pistillate and fertile (Nesom 2006). Disk florets measure 4 to 4.5 mm long, and ray florets when they have ligules can be up to 11 mm in length (Cronquist et al. 1994; Nesom 2006). Dwarf yellow fleabane produces a cypsela or dry, single–seeded fruit, which is two-nerved, hairy, and has an outer pappus of few, slender, inconspicuous bristles and an inner pappus of 15 to 25 bristles (Cronquist 1947; Cronquist et al. 1994; Nesom 2006).

Distinguishing varieties. Dwarf yellow fleabane varieties are morphologically distinguished by their pubescence and flowers. Varieties can also often be distinguished by their distributions, which have little overlap in area and elevation. See earlier Distribution and Elevation sections.

Figure 3. Erigeron chrysopsidis var. austiniae. Photo: Steve Matson, 2006, hosted by CalPhotos.

Variety austiniae produces stems with spreading hairs of essentially equal lengths (Nesom 1992a, 2006). Involucres are 4.5 to 6 mm high. Ligules of ray florets are either absent or scarcely or failing to exceed the involucre or disk florets. Disk corollas measure 3.5 to 4.5 mm long (Nesom 2006; Hitchcock and Cronquist 2018). Numerous collections of variety austiniae in northwestern Owyhee County, Idaho, and northern Malheur County, Oregon, produced short ligules (1–3 mm or rarely 4 mm long), but elsewhere in the range of variety austiniae production of even tiny ligules is rare (Nesom 1992a). Variety austiniae can also be confused with rayless shaggy fleabane (E. aphanactis) where their distributions overlap (R. Johnson, Brigham Young University, personal communication, June 2019).

Variety brevifolius grows to 1.6 to 2.4 in (4–6 cm) tall (Piper 1900). Stems have appressed to spreading hairs of even or uneven lengths and are leafless for about 75 to 90% of their total length (Piper 1900; Nesom 2006; Hitchcock and Cronquist 2018). Involucres measure 3.5 to 5.5 mm high with 20 to 50 ray florets with ligules measuring up to 7 mm long and surpassing the involucre. Disk corollas measure 2.5 to 4.5 mm long (Nesom 2006; Hitchcock and Cronquist 2018). Variety brevifolius is in every way smaller than the other varieties (Piper 1900).

Variety chrysopsidis produces stems with spreading hairs of mostly uniform lengths (Nesom 1992a; Hitchcock and Cronquist 2018). Flower heads are relatively large with involucres of 5 to 7.5 mm long. Ray florets have well-developed, conspicuous ligules measuring up to 11 mm long and surpassing the involucre. Disk corollas are 3 to 4.5 mm long (Nesom 1992a, 2006; Hitchcock and Cronquist 2018).

Reproduction

Dwarf yellow fleabane reproduces from seed. Throughout the species range, flowers are most common from May through July, although they may be present as late as August (Nesom 1992b, 2006). Self-compatibility or self-incompatibility of flowers was not reported, but fleabanes attract pollinators (James and Nunnallee 2011) and are recommended in plantings to encourage pollinators (Ogle et al. 2011).

Ecology

Dwarf yellow fleabane occupies dry, gravelly or rocky, open sites in shrubland and woodland communities (Leckenby and Toweill 1983; Cronquist et al. 1994; Nesom 2006), which suggests an ability to colonize sites opened by disturbances, but few ecological studies were available.

Post–fire recovery of dwarf yellow fleabane may depend on fire season or fire severity. After an August fire in Wyoming big sagebrush (A. tridentata subsp. wyomingensis) in southeastern Oregon, dwarf yellow fleabane was considered a “severely impacted” species. Cover of dwarf yellow fleabane on burned plots was 80% or lower than that of prefire and unburned reference areas for up to 4 years after fire. The August fire removed all Wyoming big sagebrush, and density of yellow rabbitbrush (Chrysothamnus viscidiflorus) resprouts was low in the first post-fire year (Bates et al. 2007). Dwarf yellow fleabane was just “slightly reduced” by a fall prescribed fire in Wyoming big sagebrush on the Northern Great Basin Experimental Range near Burns, Oregon. Cover of dwarf yellow fleabane was 50 to 90% of that of prefire values within 3 years of burning. The prescribed fire killed 92% of Wyoming big sagebrush plants (Bates et al. 2011). Frequency of dwarf yellow fleabane was slightly greater on burned than control plots in the first post-fire year following a fall prescribed fire in Wyoming big sagebrush in south-central Oregon. The prescribed fire consumed about 80% of the understory. Frequency of dwarf yellow fleabane was 0% on both control and preburn plots. In 1998, frequency of dwarf yellow fleabane was 12% on control and 4% on 1–year-old burned plots (Wrobleski 1999).

Wildlife And Livestock Use

Dwarf yellow fleabane is consumed by a variety of wildlife species. At the Starkey Experimental Forest in the Blue Mountains of northeastern Oregon, dwarf yellow fleabane was considered unpalatable but made up nearly 4% of the summer diet composition of elk (Cervus elaphus) (Stewart et al. 2011). In central Washington, least chipmunks (Tamius minimus subsp. scrutator) fed heavily on dwarf yellow fleabane in the spring and summer. From specimens in big sagebrush/mixed bunchgrass communities in Kittitas County, the mean relative frequency of dwarf yellow fleabane was 16% in stomachs collected in June and 4% in stomachs collected in July. Dwarf yellow fleabane along with Pacific lupine (Lupinus lepidus) were the most highly preferred forbs in June (Hall 1969). Dwarf yellow fleabane is also utilized by greater sage-grouse (Centrocercus urophasianus) (Rhodes et al. 2010).

Revegetation Use

Use of dwarf yellow fleabane in revegetation was not reported in the literature, but its use by wildlife (Hall 1969; Rhodes et al. 2010; Stewart et al. 2011) suggests it may be a useful component of native seed restoration mixes

Developing A Seed Supply

For restoration to be successful, the right seed needs to be planted in the right place at the right time. Coordinated planning and cooperation is required among partners to first select appropriate species and seed sources and then properly collect, grow, certify, clean, store, and distribute seed for restoration (PCA 2015).

Developing a seed supply begins with seed collection from native stands. Collection sites are determined by current or projected revegetation requirements and goals. Production of nursery stock requires less seed than large-scale seeding operations, which may require establishment of agricultural seed production fields. Regardless of the size and complexity of any revegetation effort, seed certification is essential for tracking seed origin from collection through use (UCIA 2015).

Seed Sourcing

Because empirical seed zones are not currently available for dwarf yellow fleabane, generalized provisional seed zones developed by Bower et al. (2014), may be used to select and deploy seed sources. These provisional seed zones identify areas of climatic similarity with comparable winter minimum temperature and aridity (annual heat:moisture index). In Figure 4, Omernik Level III Ecoregions (Omernik 1987) overlay the provisional seeds zones to identify climatically similar but ecologically different areas. For site-specific disturbance regimes and restoration objectives, seed collection locations within a seed zone and ecoregion may be further limited by elevation, soil type, or other factors.

The Western Wildland Environmental Threat Assessment Center’s (USFS WWETAC 2017) Threat and Resource Mapping (TRM) Seed Zone application provides links to interactive mapping features useful for seed collection and deployment planning. The Seedlot Selection Tool (Howe et al. 2017) can also guide restoration planning, seed collection, and seed deployment, particularly when addressing climate change considerations.

Occurrence Map

Figure 4. Distribution of dwarf yellow fleabane (black circles) based on geo-referenced herbarium specimens and observational data from 1881-2016 (CPNWH 2017; SEINet 2017; USDI USGS 2017). Generalized provisional seed zones (colored regions) (Bower et al. 2014) are overlain by Omernik Level III Ecoregions (black outlines) (Omernik 1987; USDI EPA 2018). Interactive maps, legends, and a mobile app are available (USFS WWETAC 2017; www.fs.fed.us/wwetac/threat-map/TRMSeedZoneMapper2.php?). Map prepared by M. Fisk, USDI USGS.

Releases

As of 2019, there were no dwarf yellow fleabane germplasm releases.

Wildland Seed Collection

Details about wildland seed collection were limited in the literature, though some harvesting clues are provided in plant photographs taken by the USDI BLM Seeds of Success (SOS) field collection crews. Seeds of individual plants mature over a period of about a week. Seeds are adapted for wind dispersal (Fig. 5) suggesting that population monitoring and revisiting sites is necessary to maximize harvests.

Wildland Seed Certification

Verification of species and tracking of geographic source is necessary whether wildland seed is collected for immediate project use or as stock seed for cultivated increase. This official Source Identification process can be accomplished by following procedures established by the Association of Official Seed Certifying Agencies (AOSCA) Pre-Variety Germplasm Program (Young et al. 2020; UCIA 2015). Wildland seed collectors should become acquainted with state certification agency procedures, regulations, and deadlines in the states where they collect.

If wildland-collected seed is to be sold for direct use in ecological restoration projects, collectors must apply for Source-Identified certification prior to making collections. Pre-collection applications, site inspections, and species and seed amount verification are handled by the AOSCA member state agency where seed collections will be made (see listings at AOSCA.org).

If wildland seed collected by a grower or private collector is to be used as stock seed for planting cultivated seed fields or for nursery propagation (See Agricultural Seed Field Certification section), detailed information regarding collection site and collecting procedures must be provided when applying for certification. Photos and herbarium specimens may be required. Germplasm accessions acquired within established protocols of recognized public agencies, however, are normally eligible to enter the certification process as stock seed without routine certification agency site inspections. For contract grow-outs, however, this collection site information must be provided to the grower to enable certification.

Collection Timing

Wildland seed collection sites will need to be scouted starting in May, which is when dwarf yellow fleabane begins to flower. Flowering can continue into August, although this is rare (Nesom 2006). The single reported dwarf yellow fleabane seed collection by the BLM Seeds of Success field crews was harvested on June 21, 2011 from a 4,240-ft (1,290 m) site in Malheur County, Oregon (USDI BLM SOS 2017).

Collection Methods

Wildland dwarf yellow fleabane seed could be harvested by hand stripping or plucking the seed heads (Fig. 6).

Several collection guidelines and methods should be followed to maximize the genetic diversity of wildland collections: 1) collect seed from a minimum of 50 randomly selected plants; 2) collect from widely separated individuals throughout a population without favoring the most robust or avoiding small stature plants; and 3) collect from all microsites including habitat edges (Basey et al. 2015). General collecting recommendations and guidelines are provided in online manuals (e.g., ENSCONET 2009; USDI BLM SOS 2021).

It is critical that wildland seed collection does not impact the sustainability of native plant populations. Collectors should take no more than 20% of the viable seed available at the time of harvest (USDI BLM SOS 2021). Additionally, care must be taken to avoid the inadvertent collection of weedy species, particularly those that produce seeds similar in shape and size to those of dwarf yellow fleabane.

Post-Collection Management

Although not specifically discussed in the literature, post-collection management of dwarf yellow fleabane seed likely requires attention similar to that of most wildland seed. Seed should be dried thoroughly before storing and if insects are suspected, insect strips can be used or seed can be stored at low temperatures to prevent substantial loss to insect damage.

Figure 7. Dwarf yellow fleabane seed collected from native stands in Oregon. Photo: USDI BLM ORO30 SOS.

Seed Cleaning

Seed cleaning procedures used by the Bend Seed Extractory for lots less than 5 lbs (2,270 g) were as follows (K. Harriman, U.S. Forest Service, personal communication, April 2019). Desert yellow fleabane seed (Fig. 7) would first be sieved to remove non-seed plant material. For very small seed lots, the pappus can be removed by hand-rubbing, while larger seed lots would be put through a Missoula de-winger to remove the pappus. The seed lot is then sieved again to remove any material smaller than the seeds and then processed through a continuous seed blower. If inert material remains that differs in shape or size of the seed, the lot would then be processed through a clipper seed cleaner and sieved again, if necessary (K. Harriman, U.S. Forest Service, personal communication, April 2019).

Figure 5. Dwarf yellow fleabane plant just beginning to produce seed. Photo: USDI BLM ORO30 SOS.

Figure 6. Erigeron chrysopsidis var. austiniae seed head. Photo: Steve Matson, 2006, hosted by CalPhotos.

Seed Storage

Dwarf yellow fleabane is orthodox. After 47 days of storage at 15% relative humidity and -4 °F (-20 °C), seeds retained 100% viability (RGB Kew 2017).

Seed Testing

Seed viability is tested using the general procedures described for other Asteraceae genera as no specific AOSA procedure exists for dwarf yellow fleabane (AOSA 2010). There is no AOSA rule for testing germination or purity of dwarf yellow fleabane, but there is one for germination of aspen fleabane (Erigeron speciosus) seed, which may provide a good starting point. Purity standards are also listed for aspen fleabane (AOSA 2016).

Germination Biology

There were no germination studies on dwarf yellow fleabane seed, but Young and Young (1986) suggest that seed from fleabane species requires light to germinate. Germination of the related Piper’s daisy (E. piperianus) was examined by Link et al. (2015) who collected seed in June, stored it at room temperature, and germinated it by burying the seed just below the surface in a greenhouse. Germination success was 50 ± 8%.

Wildland Seed Yield And Quality

Post–cleaning seed yield and quality was reported for a single dwarf yellow fleabane seed lot collected in Oregon (USFS BSE 2017). The USFS Bend Seed Extractory received 0.05 lb of wildland collected seed. Clean weight was 0.008 lb, for a cleanout ratio of 0.16. There were 1,440,000 seeds/lb (3,174,603 seeds/kg). Purity was 95%, fill was 99%, viability was 96%, and pure live seed (PLS) was 1,354,320 seeds/lb (2,985,714 seeds/kg). These results suggest that dwarf yellow fleabane seed is tiny and can be cleaned to high level of purity and fill. Viability of fresh seed can be high as well (USFS BSE 2017).

Marketing Standards

Acceptable seed purity, viability, and germination specifications vary with revegetation plans. Purity needs are highest for precision seeding equipment used in nurseries, while some rangeland seeding equipment handles less clean seed quite well.

Agricultural Seed Production

There was no research on growing dwarf yellow fleabane for seed increase in the available literature. See other species reviews or chapters here: aspen fleabane (E. speciosus) and desert yellow fleabane (E. linearis) for more on Agricultural Seed Production and Wildland Seeding and Planting.

Agricultural Seed Certification

In order to minimize genetic changes in specific accessions of native species when increased in cultivated fields, it is essential to track the geographic source and prevent inadvertent hybridization or selection pressure. This is accomplished by following third party seed certification protocols for Pre-Variety Germplasm (PVG) as established by the Association of Official Seed Certification Agencies (AOSCA). AOSCA members in the U.S., Canada, and other countries administer PVG requirements and standards that track the source and generation of planting stock. Field and cleaning facility inspections then monitor stand establishment, proper isolation distances, control of prohibited weeds, seed harvesting, cleaning, sampling, testing, and labeling for commercial sales (Young et al. 2020; UCIA 2015).

Seed growers apply for certification of their production fields prior to planting and plant only certified stock seed of an allowed generation (usually less than four). The systematic and sequential tracking through the certification process requires preplanning, knowing state regulations and deadlines, and is most smoothly navigated by working closely with state certification agency personnel. See the Wildland Seed Certification section for more information on stock seed sourcing.

Nursery Practice

Growth of dwarf yellow fleabane in the greenhouse or outdoor nursery setting was not described in the literature but is likely similar to Piper’s daisy. Growth of Piper’s daisy in a greenhouse by Link et al. (2015) involved sowing seed in 164-ml cone-tainers filled with 46% potting soil containing a slow–release fertilizer, 46% sand, 4% perlite, and 4% vermiculite. Growth temperatures were controlled at about 80 °F (27 °C) day and 61 °F (16 °C) night. Irrigation was automated to optimize germination and growth with more irrigation during seed germination and less during growth. Plants were fertilized using N:P2O5:K2O 20-20-20 (10-ml solid dissolved in 7.6 l of water).

Wildland Seeding And Planting

Use of dwarf yellow fleabane in revegetation or restoration was not reported in the literature but may respond similar to Piper’s daisy. Link et al. (2015) reported on establishing Piper’s daisy. After planting in the winter and by the spring of the second growing season, survivorship had dropped to 21%, but summer seed production occurred on 99% of remaining plants, resulting in 121 new plants in the summer of the third growing season.

Dwarf yellow fleabane naturally occurs on dry, gravelly or rocky, open sites and tolerates shallow basalt soils in sagebrush, juniper, ponderosa pine, and alpine communities (Leckenby and Toweill 1983; Cronquist et al. 1994; Nesom 2006; Bartuszevige et al. 2012). For more information on the habitats where dwarf yellow fleabane and specific varieties could be used in revegetation efforts, see earlier Distribution, Habitat and Plant Associations, and Elevation sections.