Plant Assessment Form

Volutaria tubuliflora

Synonyms: Amberboa atlantica; Volutaria lippii subsp. tubuliflora

Common Names: desert knapweed; Mediterranean knapweed

Evaluated on: 27-Dec-16

List committee review date: 26/01/2017

Re-evaluation date:

Evaluator(s)

Mona Robison/Science Program Manager
Cal-IPC
916-802-2004
rrobison@cal-ipc.org

List commitee members

Elizabeth Brusati
Tim Hyland
Eric Wrubel
Irina Irvine
Holly Forbes
Jutta Burger
Naomi Fraga
Denise Knapp
Chris McDonald
Ron Vanderhoff
John Knapp

General Comments

When V. tubuliflora was first detected in San Diego it was mis-identified as V. canariensis, and is still listed in the Jepson eFlora as V. canariensis. Recenly, Chris McDonald determined that a specimen from Orange County in Newport Bay from 1987 was also V. tubuliflora, moving the introduction date and location to 1987 in Orange County.

The clone of Volutaria that has established at least at the Anza Borrego and Newport colonies are both a naturally uncommon floral morph. This is apparently the same morph that has invaded Chile. However, this morph is uncommon in the native V. tubuliflora range of northern Africa/Mediterranean basin. If all three widely separated California infestations are determined to be the same genotype and also the same as that is in Chile, then it is likely (not certain) that all of the California infestations originated from a single introduction, and dispersed thereafter (Vanderhoff, pers. comm.). I agree the most likely path of Volutaria spread in California is a single introduction and then more local spread out from the first infestation (McDonald, pers. comm.).

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited
Alert Status? No Alert
Documentation? 2.5 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes U Anecdotal
Impact?
Four-part score UBDD Total Score
C
1.2 ?Impact on plant community B. Moderate Observational
1.3 ?Impact on higher trophic levels D. Negligible Observational
1.4 ?Impact on genetic integrity D. None Reviewed Scientific Publication
2.1 ?Role of anthropogenic and natural disturbance in establishment A. Severe Observational
Invasiveness?
Total Points
19 Total Score A
2.2 ?Local rate of spread with no management A. Increases rapidly Observational
2.3 ?Recent trend in total area infested within state A. Increasing rapidly Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal A. High Observational
2.6 ? Potential for natural long-distance dispersal A. Frequent Observational
2.7 ?Other regions invaded C. Already invaded Observational
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate Other Published Material
Distribution?
Total Score C
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Other Published Material

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? U Anecdotal
Identify ecosystem processes impacted:

Deep taproot may draw down the water table, but no studies have been done to document this. Primarily occurs in dry habitats with deeper water table, does occur adjacent to desert washes where moisture is likely to be higher than surrounding areas (McDonald, pers. comm.).


Sources of information:

McDonald, C. Personal communication


Question 1.2 Impact on plant community composition,
structure, and interactions?
B Observational
Identify type of impact or alteration:

It is possible that stands of V. tubuliflora could become dense enough to crowd out native vegetation. "My best estimate is that it can outcompete native plants. In Newport there are very few other weeds when the Volutaria canopy is thick (McDonald pers. comm.)." The population in Chula Vista is dense and appears to have been growing for several years (Giessow, pers. comm.).

Based upon field observations, this is a very early germinator (Sept. In Newport Beach), but with only one year of experience as a basis. This very early germination is much sooner that the native flora and likely shades and inhibits the native species. This is similar in phenology to adjacent invasive species in these same areas, such as Brassica nigra, Sisymbrium irio and Bromus spp. There is even observed competition among these species. My other comment has to do with possible allelopathic qualities. Phytotoxins and phenols appear to be documented in several species of the closely related Centaurea genus, although a quick search did not reveal any studies of this with Volutaria. (Vanderhoff, R. pers. comm.).


Sources of information:

Harris et al. 2015
Giessow, J. Personal communication
McDonald, C. Personal communication
Vanderhoff, R. Personal communication


Question 1.3 Impact on higher trophic levels? D Observational
Identify type of impact or alteration:

V. tubuliflora becomes tall enough to block movement of animals, if it grows in dense stands. This is occurring in Orange and coastal San Diego County populations. Herbivores seem to prefer native annuals to Volutaria. In the field Volutaria is generally not well grazed by herbivores (most likely caterpillars) and usually only shows minor damage (McDonald, C. pers. comm).


Sources of information:

Harris et al. 2015
Jepson eFlora 2016.
McDonald, C. Personal communication
Vanderhoff, R. Personal communication
Giessow, J. 2016.


Question 1.4 Impact on genetic integrity? D Reviewed Scientific Publication

Volutaria and its close relative Centaurea are not represented by any native species in California so there is no opportunity to cross with native species and cause impacts to genetic integrity.


Sources of information:

Calflora 2016
Jepson eFlora


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
A Observational
Describe role of disturbance:

The pathway for establishment of V. tubuliflora in California is unknown. However, where it has been introduced it spreads rapidly in areas prone to seasonal flooding or along roadsides. It is highly likely that if it is introduced elsewhere it will quickly establish, with or without disturbance. In early 2017 a new large population was found in Upper Newport Bay, located about a mile from the infestation discovered in March 2015. The population contained thousands of plants in some very dense patches, indicating it is not recently established (Vanderhoff, pers. comm.). The two Newport colonies are in rather highly traveled areas and the occurrences tend toward road and trail edges first, but do extend into nondisturbed areas (McDonald, Burger and Vanderhoff, pers. comms.).
In desert it occurs in disturbed and undisturbed areas equally (McDonald, pers. comm). This question is scored as Severe since V. tubuliflora can establish in undisturbed areas.


Sources of information:

Harris et al. 2015
Burger, J. Personal communication.
McDonald, C. Personal communication
Vanderhoff, R. Personal communication


Question 2.2 Local rate of spread with no management? A Observational
Describe rate of spread:

V. tubuliflora was first thought to be introduced in Borrego Springs in 2010, with a small number of plants observed in 2011, 2012 and 2013. After the monsoonal flooding in summer 2013, almost one thousand plants germinated in the mud left behind by the water. After Borrego Springs finally got some decent winter rain in late 2014, almost ten thousand plants germinated, a factor of ten more plants than were seen one year earlier. In early 2017 a new large population was found in Upper Newport Bay, located about a mile from the infestation discovered in March 2015. The population contained thousands of plants in some very dense patches, indicating it is not recently established (Vanderhoff, pers. comm.). Recently an herbarium specimen from 1987 from the population in Newport Bay was determined to be V. tubuliflora, moving the introduction date back to that time. This indicates the rate of spread of the Newport Bay population is perhaps B, increasing less rapidly (Vanderhoff, pers. comm.), however Burger considers the rate of spread as an A for the Newport Bay population. This question is scored as A since the Borrego Springs population is thought to be increasing at that rate.


Sources of information:

Harris et al. 2015
McDonald, C. Personal communication
Vanderhoff, R. Personal communication


Question 2.3 Recent trend in total area infested within state? A Observational
Describe trend:

V. tubuliflora was first discovered in Borrego Springs in 2010, with a small number of plants observed in 2011, 2012 and 2013. After the monsoonal flooding in summer 2013, almost one thousand plants germinated in the mud left behind by the water. After Borrego Springs finally got some decent winter rain in late 2014, almost ten thousand plants germinated, a factor of ten more plants than were seen one year earlier. V. tubuliflora was detected in Orange County in 2015 with as many as 3,000 plants, and recently R. vanderhoff located another population with thousands of plants a mile from the previous detection (Vanderhoff pers comm.). In 2016, Jason Giessow reported a 1.2 acre population with over 50,000 plants in Chula Vista, coastal San Diego county. This population is likely a few years old given its density and extent (Giessow 2016). ADD SOME ABOVE DISCUSSION HERE ALSO.


Sources of information:

Harris et al. 2015
Giessow, J. Personal communication
Giessow, J. 2016
Vanderhoff, R. Personal communication


Question 2.4 Innate reproductive potential? A Reviewed Scientific Publication
Describe key reproductive characteristics:

Annual plant which blooms from April to June in California (Jepson eFlora). Bloom can be as early as January in the desert in irrigated orchards and March along roadsides (McDonald, pers. comm.). Additionally, blooming was observed starting in February 2016 in Orange County, and as late as April when they were pulled so the end of flowering in that population was not observed that year (Vanderhoff pers. comm.)


Sources of information:

Jepson eFlora 2016
McDonald, C. Personal communication
Vanderhoff, R. Personal communication


Question 2.5 Potential for human-caused dispersal? A Observational
Identify dispersal mechanisms:

It is not known how V. tubuliflora was introduced into California, but human introduction is the likely vector. Since its introduction it has been found along roadsides, in disturbed areas and at trail heads. Its also found in 3 well separated populations each about 80 miles apart. So long distance, and most likely human, dispersal seems quite probable (McDonald, C. pers. comm.).


Sources of information:

Calflora 2016
Harris et al. 2015
McDonald, C. Personal communication


Question 2.6 Potential for natural long-distance dispersal? A Observational
Identify dispersal mechanisms:

V. tubuliflora was observed to be spreading after flooding-induced rains in Borrego Springs. It could also be spread by wind.
Dispersal distances can be over 1 km (McDonald, pers. comm.).


Sources of information:

Calflora 2016
Harris et al. 2015
McDonald, C. Personal communication


Question 2.7 Other regions invaded? C Observational
Identify other regions:

V. tubuliflora is native to the Canary Islands, northern Africa and southern Europe. It is also invasive in Saudi Arabia and Chile. In Chile it grows in arid desert in an area with 20 to 30mm annual precipitation (Tellier 2014). While it has invaded desert habitats in San Diego County, its presence in Newport Bay and coastal San Diego County indicate it has the potential to spread into more community types which are not yet invaded.


Sources of information:

Calflora 2016
Harris et al. 2015
McDonald 2016
McDonald, C. Personal communication
Teillier et al. 2014


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? B Other Published Material

V. tubuliflora (then called V. canariensis) was first documented in California in February 2010 and was vouchered in 2011 in San Diego County near Borrego Springs. Since that time it has been detected in Orange County and in coastal San Diego county. When V. tubuliflora was first detected in San Diego it was mis-identified as V. canariensis, and is still listed in the Jepson eFlora as V. canariensis Recent review of an herbarium specimen of V. muricata from Newport Bay area indicates that the species was actually V. tubuliflora, which would move the introduction date of the species in California to 1987 in Orange County (McDonald pers. comm.)


Sources of information:

Calflora 2016
CCH 2016
Harris et al. 2015
Jepson eFlora 2016
McDonald, C. Personal communication


Question 3.2 Distribution/Peak frequency? D Other Published Material
Describe distribution:

V. tubuliflora occurs in desert dunes and scrub, as well as coastal scrub and urban road edges in Southern California. Currently populations are small where it occurs (Calflora).


Sources of information:

CCH 2016
Calflora 2016
Harris et al. 2015
Jepson eFlora 2016
Giessow 2016


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter Yes
Populations of this species produce seeds every year. Yes
Seed production sustained over 3 or more months within a population annually Yes
Seeds remain viable in soil for three or more years Yes
Viable seed produced with both self-pollination and cross-pollination Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes No
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned No
Total points: 7
Total unknowns: 1
Total score: A?

Related traits:

Each plant produces 2,500 seeds (OC CNPS). Blooming period may be as long as February to June, so seed production is assumed to be over three months (Vanderhoff pers. comm.) VIABILITY -- TREATING SINCE 2014 SINCE FOUND IN 2014, STILL COMING UP, JUTTA COMMENT

I WOULD CHANGE "SEEDS REMAIN VIABLE IN SOIL FOR THREE OR MORE YEARS" TO A "YES" BECAUSE WE ARE STILL SEEING SEEDLINGS EMERGE IN 2017 IN BIG CANYON AT A SITE WHERE CONTROL WAS INITIATED IN 2014 (JB)

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirs
Aquatic Systemsrivers, streams, canals
estuaries
Dunescoastal
desertD, < 5%
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrubD, < 5%
Sonoran desert scrubD, < 5%
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): B
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions