# Skaneateles Conservation Area/Invasive species/Cirsium
## Cirsium (plume thistles)

Three Eurasian plume thistles (Cirsium) are considered to be invasive in New York State and are of concern at the Skaneateles Conservation Area (SCA):
* Cirsium vulgare (bull thistle) is known to be present and fairly common at the SCA and is listed as moderately invasive in NY, NYS & FL Tier 4.
* Cirsium arvense (creeping thistle) is probably present at the SCA and is listed an highly invasive in NY, NYS tier 4 and FL Tier 3.
* Cirsium palustre (marsh thistle) is known to be present in Madison, Herkimer and Otsego counties, is listed as moderately invasive in NY, and should be watched for at the SCA.
It should be noted that there are several native Cirsium species that may be present in the area:
* Cirsium muticum (swamp or fen thistle)
* Cirsium discolor (field thistle)
* Cirsium pumilum (pasture thistle)
* Cirsium horridulum (yellow thistle)

## Invasiveness ranking for Cirsium arvense (creeping thistle)

Cirsium arvense (creeping thistle or "Canada" thistle) was ranked in 2009 with an invasiveness of High, based on a score of 71/100 = 71%. The Ecological Invasiveness listed in 2021 remains High and placed in NYS Tier 4. The Finger Lakes PRISM places it in Tier 3 for this region.
Prohibited by New York State law.

### 1. Ecological impact (20/40)

1.1. Impact on Natural Ecosystem Processes and System-Wide Parameters: Significant alteration of ecosystem processes (7/10)
* 2009: no targeted studies on the impact on natural ecosystem processes or system-wide parameters located.
* The species can grow in dense stands much taller than the rest of the herb layer and significantly limit light availability to the lower herb layer.
* Allelopathy has been suggested
* A study from Tazmania showed that extracts from the plant inhibited germination and growth of its own as well as other plant species
* No evidence of irreversible impacts to ecosystem processes.
1.2. Impact on Natural Community Structure:
1.3. Impact on Natural Community Composition:
1.4. Impact on other species or species groups:

### 2. Biological characteristics and dispersal ability (/)

2.1. Mode and rate of reproduction
2.2 Innate potential for long-distance dispersal:
2.3. Potential to be spread by human activities:
2.4. Characteristics that increase competitive advantage:
2.5. Growth vigor:
2.6. Germination/Regeneration:
2.7. Other species in the genus invasive in New York or elsewhere:

### 3. Ecological amplitude and distribution (/)

3.1. Density of stands in natural areas in the northeastern USA and eastern Canada:
3.2. Number of habitats the species may invade:
3.3. Role of disturbance in establishment:
3.4. Climate in native range:
3.5. Current introduced distribution in the northeastern USA and eastern Canada:
3.6. Current introduced distribution of the species in natural areas in the 8 NY PRISMs:

### 4. Difficulty of control (/)

4.1. Seed banks:
4.2. Vegetative regeneration:
4.3. Level of effort required:

### References for invasiveness ranking

* ↑ M.J. Jordan, G. Moore & T.W. Weldy (2008). Invasiveness ranking system for non-native plants of New York. Unpublished. The Nature Conservancy, Cold Spring Harbor, NY; Brooklyn Botanic Garden, Brooklyn, NY; The Nature Conservancy, Albany, NY. Cirsium arvense assessed by Gerry Moore, May 13, 2009.
* ↑ New York Codes, Rules and Regulations, Title 6 Section 575.3 - Prohibited invasive species

## Observations of ssss (ccc) at the SCA

The following photographs and corresponding iNaturalist observations of tttt were made at or very near the Skaneateles Conservation Area. Click on images to enlarge and read details on Wikimedia Commons or on the "iNat obs" links to view the corresponding observations at iNaturalist.
* tttt, Skaneateles Conservation Area, dd mmm yyyy. iNat obs
* File:Tttttt SCA-yymmdd nn.jpg