Skaneateles Conservation Area/Invasive species/Ligustrum

<< Prohibited invasive plants at the SCA

Ligustrum spp. (privets)

Privet (in one or more Ligustrum species) is very common at the Skaneateles Conservation Area. In some areas it's quite dense.

In general, the several privet species, none of which are native to the western hemisphere, have been found to be invasive, and some are quite difficult to control where they have naturalized. The New York Flora Atlas reports that Ligustrum obtusifolium (border privet) is by far the most common and invasive of the naturalized privets, but that Ligustrum vulgare (European privet) can be locally quite aggressive as well.

Ligustrum sp.	Privet	young twigs & stalks of floral panicles	floral-panicle length	corolla lobe to tube length ratio	tube length
L. vulgare	common privet	hairless or minutely pubescent	longer than 2"	~1/1	2.5 - 3 mm
L. obtusifolium	border privet	conspicuously hairy	1" to 2" long	1/3 - 2/3	5 - 8 mm

Invasiveness ranking for Ligustrum spp. (privets)

The relative maximum score for the two privets evaluated in 2008 was:

• Ligustrum obtusifolium (border privet) - 76.67% (high) (prohibited in New York by state law)
• Ligustrum vulgare (common privet) - 67.82% (moderate)

Ecological impact

• Ligustrum spp. (all privets):
  • Form dense thickets that shade out and take the place of native shrubs and herbaceous plants.
  • Make conditions unsuitable for native seedlings.
  • Phenolic compounds in the leaves protect plants from leaf-feeding insects which include native herbivorous species

• Ligustrum obtusifolium (border privet):
  • Can form exceptionally large stands, which reduce light availability and eliminate layers below.
  • May outcompete native shrubs in regenerating communities and remain persistent in these areas thus resulting in significant reduction in the populations sizes of these native species.

• Ligustrum vulgare (common privet):
  • Dense growth clearly limits light availability to layers below thus influencing ecosystem processes to a minor degree.

Biological characteristics and dispersal ability

• Ligustrum spp. (all privets)
  • Resprout readily and produce fairly abundant seed with high viability, but may produce less fruit in low-light situations.

• Ligustrum obtusifolium:
  • Birds consume fruits and spread seeds long distances; vegetative spread through root suckering.
  • Formerly sold as an ornamental landscape plant and used for waste landfill remediation but now prohibited in NY.
  • Disposal of yard waste and highway maintenance may transfer seeds.

Observations of Ligustrum spp. (privets) at the SCA

The following photographs and corresponding iNaturalist observations of Ligustrum 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.

• Ligustrum, at the south end of the bucksuckle old field at the SCA, 29 Mar 2011. iNat obs
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• Ligustrum, Skaneateles Conservation Area, 17 Mar 2011. iNat obs
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• Ligustrum, along the Federal Farm Road at the SCA, 3 May 2012. iNat obs
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• Ligustrum, at the south end of the bucksuckle old field at the SCA, 3 May 2012. iNat obs
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• Ligustrum, west of the transfer station at the SCA, 3 May 2012. iNat obs
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