Created by: Melanie Davis
Created on: Sunday, Sep 22nd, 2024
Created on: Sunday, Sep 22nd, 2024
Yes or No:
Yes
Points:
1
Confidence Level:
Very High
Answer / Justification:
Eragrostis echinochloidea is native to South Africa and is introduced in Arizona, California, northern Mexico, and Israel. It is considered naturalized in Arizona and Mexico. Randall (2017) lists E. echinochloidea as naturalized in Europe and Israel, however there is not sufficient evidence with species documentation to support this as there are very little documentation of this taxon in these regions. In Arizona and Mexico, however, it is well supported in literature, management, and documentation that this taxon is naturalized.
Reference(s):
Yes or No:
Yes
Points:
2
Confidence Level:
Very High
Answer / Justification:
Eragrostis echinochloidea is naturalized in Arizona, which has a similar climate to California (the region in question). Regions that it occupies in Mexico also share a similar climate. Where it is native in South Africa, it can be found in the western Cape and near Johannesburg, which also share a similar climate to California. However, this is the edge of the species distribution in its native range, and it is primarily found in a region of South Africa which does not match the climate of California. Randall (2017) notes that its preferred climates are Mediterranean, Subtropical, and Tropical.
Reference(s):
Yes or No:
Yes
Points:
2
Confidence Level:
High
Answer / Justification:
Eragrostis echinochloidea is considered invasive in Mexico by Randall (2017). Randall cites a 2006 web page from Conabio that is no longer available and since 2006 there have been regulation changes regarding the definition changes of 'invasiveness' in Mexico, and because I was unable to find Eragrostris echinochloidea on any recent lists I can only assume that it is not longer considered invasive here.
However, Pima County (Webb 2020) considers this species as invasive where it has spread from roadsides into multiple ecosystems.
Reference(s):
Yes or No:
Yes
Points:
3
Confidence Level:
High
Answer / Justification:
While the species is not widely considered invasive, Pima County has included it in invasive species monitoring programs where it is noted as "invading multiple ecosystems types including desert, thornscrub, semi-desert grasslands, xeric riparian areas, and mesic riparian areas...African lovegrass may pose a threat to MSCP covered species, particularly
in thornscrub and desert areas where it alters vegetation structure and provides a source of
fine fuels for wildfires." (Webb 2020). Pima County, Arizona, does have a similar climate to California.
Yes or No:
Yes
Points:
1
Confidence Level:
Very High
Answer / Justification:
Eragrostis is an extensive monophyletic genus with approximately 350 taxa distributed across the word, about 24 of which are introduced outside of their native range. No species of Eragrostis are currently considered invasive in California, however six other non-native species and one subspecies of the genus have been documented in California. Eragrostis lehmanniana, native to South Africa, has become invasive in southwestern United States, primarily Arizona and Mexico, where it was introduced for restoration. The regions of Arizona and Mexico that this species has invaded are a similar climate to California, similar to Eragrostis echinochloidea. This taxon has also been found in California and should be considered for a PRE review.
Reference(s):
Yes or No:
No
Points:
0
Confidence Level:
High
Answer / Justification:
The majority of this species native range is in Botswana and Namibia, regions that are more arid than the region of concern. In the limited regions that it has become naturalized, the climate does not match that of California. While the Precipitation and Hardiness layers on the Climate Match tool do match the primary native range for this taxon does match southern California and the southwestern desert region, overall the majority of the species range does not match.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
Medium
Answer / Justification:
Eragrostis echinochloidae is a perennial bunch grass that can reach 1 meter tall; the plants grow in dense tufts or clumps and form mats (are cespitose), with erect stems. Plants that form dense clumps are capable of stabilizing substrate and potentially causing thick mats, thus have the ability to crowd out natives. However the plant is not a vine and does not have an overhanging cover and would not be at risk of smothering natives. This taxon has been reported as altering vegetation structure where it has invaded multiple ecosystems types including desert, thornscrub, semi-desert grasslands, xeric riparian areas, and mesic riparian areas, and has been reported as a potential threat to MSCP covered and sensitive species in Pima County, AZ.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
High
Answer / Justification:
Eragrostis echinochoidea is reported as being capable of initiating grass-fire cycles in USA and provides a source for fine fuels for wildfires. In general, perennial grass dominated ecosystems burn more completely and generate higher temperatures than herbaceous and woody systems. However, it is not reported as forming monocultures where it has invaded, so while it can contribute positively to increased fire risk, it likely won't singularly drive fire.
Reference(s):
Yes or No:
No
Points:
0
Confidence Level:
Very High
Answer / Justification:
Eragrostis echinochloidea is was not listed by CDFA (2015) as a noxious weed and is not included in the Cornell list of poisonous plants (2018) nor listed in the California Poison Control System (2023). It was potentially introduced to the US for the regeneration of rangelands and as a forage grass, however it does not have a high forage value and has a rating of moderate grazing value. Thus, while it might not be the most palatable forage grass, it is not toxic and does not pose as a health risk.
Reference(s):
Yes or No:
No
Points:
0
Confidence Level:
Very High
Answer / Justification:
Eragrostis echinochloidae is a perennial bunch grass that can reach 1 meter tall; the plants grow in dense tufts or clumps and form mats (are cespitose), with erect stems (culms). Plants that form dense clumps are capable of stabilizing substrate and potentially causing thick mats, however due to this plants height and lack of thorns, it does not prove as a physical barrier to humans, animals, or livestock.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
Medium
Answer / Justification:
Eragrostis echinochloidea has been reported as sometimes rooting at the nodes. Species of the Eragrostis genus can be stoloniferous or rhizomatous. There is very little other documentation of this taxon spreading or reproducing vegetatively, so while it has been reported that it can, this does not seem to be the primary mode of reproduction.
Reference(s):
Yes or No:
No
Points:
0
Confidence Level:
High
Answer / Justification:
As stated in question 11, Eragrostis echinochloidea has been reported as having the ability to root at the nodes, however this is not a common method of reproduction.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
Very High
Answer / Justification:
Eragrostis echinochoildea primarily reproduces from seed.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
High
Answer / Justification:
I was unable to find calculations in the literature of the number of viable seed Eragrostis echinochloidea can produce however I was able to ascertain an approximate number by calculating the average fertile florets per spikelet (5-16) and spikelets per raceme (~10) using numbers provided in the taxon's treatment. An individual inflorescence can easily produce on average 100 viable seeds per year, thus, a single plant would only need to produce 10 inflorescences per year. Personal observation of 147 verified photo occurrences on iNaturalist show that is not an uncommon occurrence, however it depends on the size of the individual plant. Young plants appear to be producing <10 inflorescences at a given point, and well established older individuals produce well over 10. Observational evidence shows that this species will flower throughout the year, and so the average adult plant could easily produce over 1000 seeds per year.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
Medium
Answer / Justification:
Gutiérrez-Gutiérrez et al. (2022) reports that germination of seeds occur in about 2 days after being stored in paper bags at 24C (75.2F) for 2-3 years after being cleaned, however germination rate was low, at less than 3%. These results are from a lab setting.
However, other species in the Eragrostis genus have well documented germination rates. Eragrostis plana showed high germination rates (up to 98%) in optimal simulated conditions (Bittencourt et al 2017). Bittencourt et al (2016) also found a 85% germination rate of Eragrostis tenuifolia in a similar study. In an experiment testing seed treatments on Eragrostis lehmanniana, Haferkamp and Jordan (1977) found that the control sample had a germination rate of 36% just 48 hours after imbibition. In an earlier study, Wright (1973) found germination of untreated Eragrostis lehmanniana seeds to be as high as 80% 150 weeks post-harvest.
The ample evidence that Eragrostris species have high germination rates imply that E. echinochloidea would too given a more controlled experiment. Thus, I am answering Yes with a Medium confidence here.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
Very Low
Answer / Justification:
CABI states that it has been reported that Eragrostis echinochloidea has a slow growth rate, however I was unable to verify this with the listed source (out of commission site). I was also unable to find any observations or reports regarding the amount of time it takes this species to develop fruit.
However, many perennial grasses, including species of Eragrostis, produce seed within three years; Eragrostis secundiflora produces viable seed within the first year of planting (Maher and Reilley 2016).
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
Very High
Answer / Justification:
Two sources (CalFlora and Flora of Israel) site this taxon of having a 1-2 month flowering period, however the sample size for both of these sources are unknown, and assumed to be small as vouchering of the taxon in California and Isreal is minimal. California Consortium of Herbaria list flowering time as in the spring and fall (February, April, September, and October) with a sample size of 9, however some of the vouchers used here were collected in South Africa, which, being in the Southern Hemisphere, has opposite seasons from the United States. That being said, in looking at verified iNaturalist photo observations in South Africa, Eragrostis echinochloidea can be found flowering throughout all 12 months of the year (n=72). In the Northern Hemisphere this species has been documented on iNaturalist (verified photos) as flowering almost every month out of the year, excluding January, July, and December (n=75). While it is unknown of one individual will produce seeds more than twice a year, it is appears that seeds can be continuously produced for over three months out of the year.
Reference(s):
Yes or No:
No
Points:
0
Confidence Level:
Low
Answer / Justification:
Eragrostis echinochloidea can be found throughout grazing rangeland, and some assessments have speculated that with proximity to livestock, the species could use animals as a vector, especially because of the minuscule size of the seeds (<1mm), However, seed size is not enough evidence and I was unable to find other supporting documentation of long distance dispersal via mammals or birds.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
High
Answer / Justification:
Eragrostis echinochloidea is naturalized and native to arid regions and is not generally find in wet environments, therefore dispersal via water is unlikely. However, this species, and its close relatives are dispersed via wind and have seed morphology that aides in distance wind dispersal (such as winged palea), which it shares with other naturalized members of the Eragrostis genus.
Reference(s):
Yes or No:
Yes
Points:
1
Confidence Level:
Medium
Answer / Justification:
This species presence near highways, lots, disturbed sites and cattle farms suggests it is moving with vehicles, or otherwise anthropogenically. In Mexico, E. echinochloidea was first reported as an escaped forage grass in 2001 near a toll station of Road 15 at Magdalena de Kino, Sonora.
Reference(s):
Notes:
- < 13 : Low Potential Risk
- 13 - 15 : Moderate Potential Risk
- > 15 : High Potential Risk
PRE Score:
19
Number of questions answered:
20
Screener Confidence (%):
78.0
Evaluation visibility:
Public - accessible to all site users