Plant Assessment Form

More Geranium purpureum resources

Geranium purpureum

Synonyms: Geranium robertianum subsp. purpureum; Pelargonium purpureum

Common Names: little robin

Evaluated on: 27-Dec-16

List committee review date: 25/01/2017

Re-evaluation date:

Evaluator(s)

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

List committee members

Elizabeth Brusati
Tim Hyland
Eric Wrubel
Irina Irvine
Holly Forbes

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited

Alert Status? No Alert

Documentation? 3 out of 5

Score

Documentation

1.1

?Impact on abiotic ecosystem processes

U. Unknown

No Information

Impact?
Four-part score UCDC Total Score
C

1.2

?Impact on plant community

C. Minor

Observational

1.3

?Impact on higher trophic levels

D. Negligible

Reviewed Scientific Publication

1.4

?Impact on genetic integrity

C. Minor/Low

Reviewed Scientific Publication

2.1

?Role of anthropogenic and natural disturbance in establishment

B. Moderate

Observational

Invasiveness?
Total Points
15 Total Score B

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)

B. Moderate

Reviewed Scientific Publication

2.5

?Potential for human-caused dispersal

C. Low

Reviewed Scientific Publication

2.6

? Potential for natural long-distance dispersal

C. Rare

Reviewed Scientific Publication

2.7

?Other regions invaded

A. Invades 3 or more ecological types

Reviewed Scientific Publication

3.1

?Ecological amplitude/Range
(see Worksheet C)

A. Widespread

Other Published Material

Distribution?
Total Score B

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? Consider the impact on the natural range and variation of abiotic ecosystem processes and system-wide parameters in ways that significantly diminish the ability of native species to survive and reproduce. Alterations that determine the types of communities that can exist in a given area are of greatest concern. Examples of abiotic processes include: - fire occurrence, frequency, and intensity; - geomorphological changes such as erosion and sedimentation rates; - hydrological regimes, including soil water table; - nutrient and mineral dynamics, including salinity, alkalinity, and pH; - light availability (e.g. when an aquatic invader covers an entire water body that would otherwise be open). Select the one letter below that best describes this species' most severe impact on an abiotic ecosystem process: A. Severe, possibly irreversible, alteration or disruption of an ecosystem process. B. Moderate alteration of an ecosystem process. C. Minor alteration of an ecosystem process. D. Negligible perceived impact on an ecosystem process. U. Unknown.	U No Information
Identify ecosystem processes impacted: There is no information available on G. purpureum's impact on abiotic ecosystem processes. This question is scored as Unknown based on lack of reported abiotic effects. Sources of information:
Question 1.2 Impact on plant community composition, structure, and interactions? Consider the cumulative ecological impact of this species to the plant communities it invades. Give more weight to changes in plant composition, structure, and interactions that involve rare or keystone species or rare community types. Examples of severe impacts include: - formation of stands dominated (>75% cover) by the species; - occlusion (>75% cover) of a native canopy, including a water surface, that eliminates or degrades layers below; - significant reduction or extirpation of populations of one or more native species. Examples of impacts usually less than severe include: - reduction in propagule dispersal, seedling recruitment, or survivorship of native species; - creation of a new structural layer, including substantial thatch or litter, without elimination or replacement of a pre-existing layer; - change in density or depth of a structural layer; - change in horizontal distribution patterns or fragmentation of a native community; - creation of a vector or intermediate host of pests or pathogens that infect native plant species. Select the one letter below that best describes this species' impact on community composition, structure and interactions: A. Severe alteration of plant community composition, structure, or interactions. B. Moderate alteration of plant community composition. C. Minor alteration of community composition. D. Negligible impact known; causes no perceivable change in community composition, structure, or interactions. U. Unknown.	C Observational
Identify type of impact or alteration: "Geranium purpureum is a major player that has taken over Sonoma Valley. I have a drainage at the Bouverie Preserve which had a small patch 4 years ago. The following year it had expanded to several acres, and several new occurrences. I find it to be much more invasive than G. robertianum, which has infested all 4 canyons of Bolinas Lagoon Preserve but never forms the thick stands of G. purpureum" (Gluesenkamp pers comm.). G. purpureum causes minor alteration of plant communities by increasing the density of the herbaceous layer in forests/woodlands in Sonoma and Napa counties. Emails from Warner, Ruygt and Wrubel (2017) indicate that G. purpureum occasionally outcompetes understory spp. In forests and woodlands. It invades a previously unoccupied niche in bare litter/duff of forests with sparse understory. In brighter locations it outcompetes with native herbs such as Trientalis and Nemophila heterophila and may form > 80% of the ground cover (Ruygt, pers. comm.). Sources of information: Gluesenkamp, D. Personal communication. Ruygt, J. Personal communication. Warner, P. Personal communication. Wrubel, E. Personal communication.
Question 1.3 Impact on higher trophic levels? Consider the cumulative impact of this species on the animals, fungi, microbes, and other organisms in the communities that it invades. Although a non-native species may provide resources for one or a few native species (e.g. by providing food, nesting sites, etc.), the ranking should be based on the species' net impact on all native species. Give more weight to changes in composition and interactions involving rare or keystone species or rare community types. Examples of severe impacts include: - extirpation or endangerment of an existing native species or population; - elimination or significant reduction in native species' nesting or foraging sites, cover, or other critical resources (i.e., native species habitat), including migratory corridors. Examples of impacts that are usually less than severe include: - minor reduction in nesting or foraging sites, cover, etc. for native animals; - minor reduction in habitat connectivity or migratory corridors; - interference with native pollinators; - injurious components, such as awns or spines that damage the mouth and gut of native wildlife species, or production of anti-digestive or acutely toxic chemical that can poison native wildlife species. Select the one letter below that best describes this species' impact on community composition and interactions: A. Severe alteration of higher trophic populations, communities, or interactions. B. Moderate alteration of higher trophic level populations, communities, or interactions. C. Minor alteration of higher trophic level populations, communities or interactions. D. Negligible impact; causes no perceivable change in higher trophic level populations, communities, or interactions. E. Unknown.	D Reviewed Scientific Publication
Identify type of impact or alteration: There is no information available on G. purpureum's impact on higher trophic levels. Herrera (1991) found that 90% of experimental G. purpureum transplants exposed to vertebrate herbivores (cattle, red deer Cervus elephas, fallow deer Dama dama and rabbits Oryetolagus cunic ulus) were consumed well before reaching reproductive size whereas 60% of transplants protected from grazing set at least one fruit. Sources of information: Herrera 1991 Tofts 2004
Question 1.4 Impact on genetic integrity? Consider whether the species can hybridize with and influence the proportion of individuals with non-native genes within populations of native species. Mechanisms and possible outcomes include: - production of fertile or sterile hybrids that can outcompete the native species; - production of sterile hybrids that lower the reproductive output of the native species. Select the one letter below that best describes this species' impact on genetic integrity: A. Severe (high proportion of individuals). B. Moderate (medium proportion of individuals). C. Minor (low proportion of individuals). D. No known hybridization. U. Unknown.	C Reviewed Scientific Publication
G. purpurem can self pollinate as well as cross pollinate. There is no documentation of it hybridizing with native Geranium species in California. Only two native California Geranium species -- Geranium bicknellii and Geranium carolinianum -- overlap with the current range of G. purpureum and could potentially hybridize. There are also many more non-native geraniums occurring in these areas (such as G. dissectum) which would be more likely to hybridize with natives and cause population changes. Sources of information: Calflora 2016 Tofts 2004
Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance in establishment? Assess this species' dependence on disturbance: both human and natural: for establishment in wildlands. Examples of anthropogenic disturbances include: - grazing, browsing, and rooting by domestic livestock and feral animals; - altered fire regimes, including fire suppression; - cultivation; - silvicultural practices; - altered hydrology due to dams, diversions, irrigation, etc.; - roads and trails; - construction; - nutrient loading from fertilizers, runoff, etc. Examples of natural disturbance include: - wildfire; - floods; - landslides; - windthrow; - native animal activities such as burrowing, grazing, or browsing. Select the first letter in the sequence below that describes the ability of this species to invade wildlands: A. Severe invasive potential: this species can establish independent of any known natural or anthropogenic disturbance. B. Moderate invasive potential: this species may occasionally establish in undisturbed areas but can readily establish in areas with natural disturbances. C. Low invasive potential: this species requires anthropogenic disturbance to establish. D. No perceptible invasive potential: this species does not establish in wildlands (though it may persist from former cultivation). U. Unknown.	A Observational
Describe role of disturbance: Anecdotal information on G. purpureum establishment and dispersal in California is available. It has become one of the more abundant weeds along roadsides in Sonoma County, especially in urban areas, but also sporadically on lesser traveled rural byways. Trails are not exempt, as I’ve seen populations in many parks and open space areas (locally) spread from along trails to more remote woodlands (Warner pers. comm.). I have seen it in oak woodlands, riparian woodlands and in ruderal settings. It’s a common and difficult garden weed. I have no recollection of it showing up in chaparral (Rugyt, pers. comm.). Based on these observations and on the establishment of other invasive Geranium species such as G. dissectum and G. molle, which are facilitated by disturbance, and G. robertianum which does not require disturbance to establish, the species is given a Moderate rating. Sources of information: Cal-IPC PAF for G. dissectum, G. molle and G. robertianum. Ruygt, J. Personal communication. Warner, P. Personal communication.
Question 2.2 Local rate of spread with no management? Assess this species' rate of spread in existing localized infestations where the proportion of available habitat invaded is still small when no management measures are implemented. Select the one letter below that best describes the rate of spread: A. Increases rapidly (doubling in <10 years) B. Increases, but less rapidly C. Stable D. Declining U. Unknown	A Observational
Describe rate of spread: Local rate of spread of G. purpureum in California without management appears to be high based on the following: Geranium purpureum is a major player that has taken over Sonoma Valley. I have a drainage at the Bouverie Preserve which had a small patch 4 years ago. The following year it had expanded to several acres, and several new occurrences (Gluesenkamp, pers. comm.) Where I have seen it, I would say Geranium purpureum is doubling in the East Bay hills, and increasing, but less rapidly near the coast in Golden Gate NRA, and Point Reyes NS (Wrubel, pers. comm.). Ruygt reports it as spreading less rapidly in Napa and Warner reports it as doubling in 10 years in Sonoma County, so the highest rate of spread is selected for this question. Sources of information: Gluesenkamp, D. Personal communication. Ruygt, J. Personal communication. Warner, P. Personal communication. Wrubel, E. Personal communication.
Question 2.3 Recent trend in total area infested within state? Assess the overall trend in the total area infested by this species statewide. Include current management efforts in this assessment and note them. Select the one letter below that best describes the current trend: A. Increasing rapidly (doubling in total range statewide in <10 years) B. Increasing, but less rapidly C. Stable D. Declining U. Unknown	A Observational
Describe trend: Local rate of spread of G. purpureum in California without management appears to be high based on reports from regional experts. Where I have seen it, I would say Geranium purpureum is doubling in the East Bay hills, and increasing, but less rapidly near the coast in Golden Gate NRA, and Point Reyes NS (Wrubel, pers. comm.). Ruygt reports it as spreading less rapidly in Napa and Warner reports it as doubling in 10 years in Sonoma County (Ruygt and Warner, pers. comms.), so the highest rate of spread is selected for this question. Sources of information: Gluesenkamp, D. Personal communication. Ruygt, J. Personal communication. Warner, P. Personal communication. Wrubel, E. Personal communication.
Question 2.4 Innate reproductive potential? Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.	B Reviewed Scientific Publication
Describe key reproductive characteristics: Reproduces by seed and is an annual or biennial so produces seed in one or two years. Flowers in California from March to October (Rugyt pers. comm.). In Spain, peak flowering occurs in March and seed dispersal and senescence in May. Based on studies in Europe, It appears plants flower and set seed rapidly after germination but do not have a long flowering period. Seeds appear to have short dormancy and germinate as soon as winter starts. Seeds sown in the autumn in Britain germinate soon afterwards. No scarification is required. Seed production per flower is low -- one study found that many flowers produced fewer than 5 viable seeds. Geranium can facultatively self-pollinate, which it regularly does. Seeds remain viable for at least 7 years. Sources of information: Calflora 2016 DiTomaso and Healy 2007 Herrera 1991 Tofts 2004
Question 2.5 Potential for human-caused dispersal? Assess whether this species is currently spread: or has high potential to be spread: by direct or indirect human activity. Such activity may enable the species to overcome natural barriers to dispersal that would not be crossed otherwise, or it may simply increase the natural dispersal of the species. Possible mechanisms for dispersal include: - commercial sales for use in agriculture, ornamental horticulture, or aquariums; - use as forage, erosion control, or revegetation; - presence as a contaminant (seeds or propagules) in bulk seed, hay, feed, soil, packing materials, etc.; - spread along transportation corridors such as highways, railroads, trails, or canals; - transport on boats or boat trailers. Select the one letter below that best describes human-caused dispersal and spread: A. High: there are numerous opportunities for dispersal to new areas. B. Moderate: human dispersal occurs, but not at a high level. C. Low: human dispersal is infrequent or inefficient. D. Does not occur. U. Unknown.	C Reviewed Scientific Publication
Identify dispersal mechanisms: Human-caused dispersal is not well documented. No information in the literature except for a description of it spreading rapidly along railroad lines in Germany. I suspect herbivores are involved in distribution but abundance can be attributed to high seed production and seed viability (Ruygt, pers. comm.). I’ve seen populations in many parks and open space areas (locally) spread from along trails to more remote woodlands — I suspect seeds are dispersed readily by numerous dispersers, especially humans, but likely including wildlife, bicycles, and horses (Warner, pers. comm.). Sources of information: Baltisberger and Waser-Walter 2009 Ruygt, J. Personal communication. Warner, P. Personal communication.
Question 2.6 Potential for natural long-distance dispersal? We have chosen 1 km as the threshold of "long-distance." Assess whether this species is frequently spread, or has high potential to be spread, by animals or abiotic mechanisms that can move seed, roots, stems, or other propagules this far. The following are examples of such natural long-distance dispersal mechanisms: - the species' fruit or seed is commonly consumed by birds or other animals that travel long distances; - the species' fruits or seeds are sticky or burred and cling to feathers or hair of animals; - the species has buoyant fruits, seeds, or other propagules that are dispersed by flowing water; - the species has light propagules that promote long-distance wind dispersal; - The species, or parts of it, can detach and disperse seeds as they are blown long distances (e.g., tumbleweed). Select the one letter below that best describes natural long-distance dispersal and spread: A. Frequent long-distance dispersal by animals or abiotic mechanisms. B. Occasional long-distance dispersal by animals or abiotic mechanisms. C. Rare dispersal more than 1 km by animals or abiotic mechanisms. D. No dispersal of more than 1 km by animals or abiotic mechanisms. U. Unknown.	C Reviewed Scientific Publication
Identify dispersal mechanisms: Geranium seeds lack obvious adaptations promoting dispersal through wind or water. Seed collecting by ants has never been observed (Herrera 1991). Seed dispersal distances are short. Seeds use ballistic dispersal over short distances with 50% of seeds landing within 44cm of the parent plant. Tortoises in Spain ingest and defecate seeds and other animals could do the same. Since the diaspores are sticky, attachment to animals could play a role in dispersal. Sources of information: Herrera 1991 Tofts 2004
Question 2.7 Other regions invaded? Assess whether this species has invaded ecological types in other states or countries outside its native range that are analogous to ecological types not yet invaded in your state (see Worksheets B, C, and D for California, Arizona, and Nevada, respectively, in Part IV for lists of ecological types). This information is useful in predicting the likelihood of further spread within your state. Select the one letter below that best describes the species' invasiveness in other states or countries, outside its native range. A. This species has invaded 3 or more ecological types elsewhere that exist in your state and are as yet not invaded by this species (e.g. it has invaded Mediterranean grasslands, savanna, and maquis in southern Europe, which are analogous to California grasslands, savanna, and chaparral, respectively). B. Invades 1 or 2 ecological types that exist but are not yet invaded in your state. C. Invades elsewhere but only in ecological types that it has already invaded in the state. D. Not known as an escape anywhere else. U. Unknown.	A Reviewed Scientific Publication
Identify other regions: G. purpureum native to Europe, northern Africa, and western Asia and is alien in South America, New Zealand, and southern Africa (Jepson eFlora). It is also noted as spreading along railroad lines in Germany. There is little information on the habitat types which G. purpureum has invaded outside its native range. Within its native range it occurs on exposed shale near the coast and inland in a variety of habiats, in dry or moist soils in protected and unprotected areas. This indicates that there are probably ecological types in California which it has not yet invaded, based on its native distribution. The geographical distribution of Geranium purpureum is essentially Mediterranean, although a finger reaches through France to south-western England and southern Ireland while there are populations at elevations up to 7000 ft. in the mountains of eastern Africa and in Macaronesia and the Azores. This species has been introduced into South America where it is found established in comparable climatic conditions on the east and west coasts and even in the Juan Fernandez islands (Baker 1957). It is also noted as currently spreading in Northwestern and Central Europe (Eliáš 2011). Sources of information: Jepson eFlora Baltisberger and Waser-Walter 2009 Herrera 1991 Baker 1957 Tofts 2004 Eliáš 2011
Section 3: Distribution
Question 3.1 Ecological amplitude/Range? Refer to Worksheet C and select the one letter below that indicates the number of different ecological types that this species invades. A. Widespread: the species invades at least three major types or at least six minor types. B. Moderate: the species invades two major types or five minor types. C. Limited: the species invades only one major type and two to four minor types. D. Narrow: the species invades only one minor type. U. Unknown.	A Other Published Material
G. purpureum was first collected in Napa county in 1976, and was not collected elsewhere in the Bay Area until the 1990s. It was collected in Butte County starting in 2008 and in Santa Cruz County in 2013, indicating its spread outward from Napa and the Bay Area. There is not a lot of information on the types of habitats that G. purpureum occurs in. Descriptions appear to be for oak woodland and grasslands, as well as urban areas and roadsides. Noted as spreading rapidly in riparian and woodland of inner North Coast ranges of California (Gluesenkamp, pers. comm.). It grows in mixed hardwood conifer forest where previously cover was sparse and primarily duff. It occurs from Carneros Valley area to Calistoga on the west range of Napa Valley, along the Napa River and more locally in the eastern part of the county. I have not seen it on the east side of Lake Berryessa. I have seen it in oak woodlands, riparian woodlands and in ruderal settings (Rugyt pers. comm.). Sources of information: CCH 2016 Calflora 2016 Jepson eFlora 2016 Gluesenkamp, D. Personal communication. Ruygt, J. Personal communication. Warner, P. Personal communication.
Question 3.2 Distribution/Peak frequency? To assess distribution, record the letter that corresponds to the highest percent infested score entered in Worksheet C for any ecological type.	D Other Published Material
Describe distribution: G. purpureum occurs in 10 counties in California and is noted to be spreading rapidly in oak woodlands, riparian woodlands and in ruderal settings (Rugyt pers. comm.). However, the proportion of these community types overall throughout California is < 5%. Sources of information: CCH 2016 Calflora 2016 Jepson eFlora 2016 Ruygt, J. Personal communication.

Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less	Yes
Dense infestations produce >1,000 viable seed per square meter	No
Populations of this species produce seeds every year.	Yes
Seed production sustained over 3 or more months within a population annually	No
Seeds remain viable in soil for three or more years	Yes
Viable seed produced with both self-pollination and cross-pollination	Yes
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:	5
Total unknowns:	0
Total score:	B? Scoring Criteria for Worksheet A A. High reproductive potential (6 or more points). B. Moderate reproductive potential (4-5 points). C. Low reproductive potential (3 points or less and less than 3 Unknowns). U. Unknown (3 or fewer points and 3 or more Unknowns).

Related traits:

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)

Major Ecological Types	Minor Ecological Types	Code? A means >50% of type occurrences are invaded; B means 20% to 50%; C means 5% to 20%; D means present but <5%; U means unknown (unable to estimate percentage of occurrences invaded)
Marine Systems	marine systems
Freshwater and Estuarine	lakes, ponds, reservoirs
Aquatic Systems	rivers, streams, canals
Aquatic Systems	estuaries
Dunes	coastal
	desert
	interior
Scrub and Chaparral	coastal bluff scrub
	coastal scrub
	Sonoran desert scrub
	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 Communities	coastal prairie
	valley and foothill grassland	D, < 5%
	Great Basin grassland
	vernal pool
	meadow and seep
	alkali playa
	pebble plain
Bog and Marsh	bog and fen
Bog and Marsh	marsh and swamp
Riparian and Bottomland habitat	riparian forest	D, < 5%
	riparian woodland	D, < 5%
	riparian scrub (incl.desert washes)
Woodland	cismontane woodland	D, < 5%
	piñon and juniper woodland
	Sonoran thorn woodland
Forest	broadleaved upland forest
	North Coast coniferous forest	D, < 5%
	closed cone coniferous forest
	lower montane coniferous forest
	upper montane coniferous forest
	subalpine coniferous forest
Alpine Habitats	alpine boulder and rock field
Alpine Habitats	alpine dwarf scrub
	Amplitude (breadth):	B
	Distribution (highest score):	D

Infested Jepson Regions

Click here for a map of Jepson regions

Central West
Sierra Nevada East

California Invasive Plant Council

Protecting California’s environment and economy from invasive plants

Plant Assessment Form

More Geranium purpureum resources

Geranium purpureum

Evaluator(s)

List committee members

General Comments

Table 2. Criteria, Section, and Overall Scores

Table 3. Documentation

Worksheet A - Innate reproductive potential

Related traits:

Worksheet C - California Ecological Types

Infested Jepson Regions