Silverthorn, Thorny Olive (Elaeagnus pungens)

Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Rosanae
Order	Rosales
Family	Elaeagnaceae
Genus	Elaeagnus

Scientific Name

Elaeagnus pungens

Common Name

thorny olive

Miller, J.H., E.B, Chambliss, N.J. Loewenstein. 2010. A Field Guide for the Identification of Invasive Plants in Southern Forests. General Technical Report SRS-119. Asheville, NC. United States Department of Agriculture, Forest Service. 126 p.

Plant

Evergreen, densely bushy shrub 3 to 25 feet (1 to 8 m) in height, with scattered sharp stubby branches and long limber projecting shoots that scramble up into adjacent trees. Thick leaves, silver-brown scaly beneath. Often found near ornamental and wildlife plantings as escaped single plants from animal-dispersed seeds.

Stem

Multiple stems and densely branched. Twigs brown, covered with brown scales, and hairy when young. Short shoots with small leaves become sharp-branched or unbranched thorns 0.4 to 1.6 inches (1 to 4 cm) long, and in second year produce leafy lateral branches, followed by flowers in fall. Lateral branches distinctly long, limber, and in late summer to spring extending beyond bushy crown and ascending into trees. Bark dark, drab and rough with projecting stubby thorns.

Leaves

Alternate, oval to elliptic and thick, 0.4 to 4 inches (1 to 10 cm) long and 0.2 to 2 inches (0.6 to 5 cm) wide. Irregular and wavy margins that may roll under. Blade surfaces silver scaly in spring becoming dark green or brownish green above and densely silver scaly with scattered brown scales beneath. Petioles 0.1 to 0.2 inch (4 to 5 mm) long, grooved above.

Flowers

October to December. Axillary clusters, each with 1 to 3 flowers, 0.4 inch (1 cm) long, silvery white to brown. Tubular with 4 lobes. Fragrant.

Fruit and seeds

March to June. Oblong, juicy drupe, 0.3 to 0.6 inch (1 to 1.5 cm) long, containing 1 nutlet. Whitish ripening to red and finely dotted with silvery to silvery-brown scales. Persistent shriveled calyx tube at tip.

Ecology

Fast-growing, weedy ornamental. Tolerant to shade, drought, and salt. Spreads by animal-dispersed seeds and occurs as scattered individuals, both in the open and under forest shade. Increases in size by prolific stem sprouts. Can climb into trees.

Resembles

Resembles autumn olive (E. umbellata Thunb.) and Russian olive (E. angustifolia L.), both of which are deciduous and are further described in this book. Autumn olive has thin leaves with silver scales (not silver brown) and abundant reddish rounded berries in fall and early winter. Russian olive has silver scaly twigs and leaf surfaces, and many yellow fruit in fall and winter.

History and use

Introduced as an ornamental from China and Japan in 1830. Frequently planted for hedgerows and on highway right-of-ways and still used for landscaping. Mistakenly planted for wildlife to escape into nearby forests and pastures.

Distribution

Found as scattered plants or small infestations throughout the region.

Management strategies

• Do not plant. Remove prior plantings, and control sprouts and seedlings. Bag and dispose of fruit in a dumpster.
• Treat when new plants are young to prevent seed formation.
• Cut, mulch, or bulldoze when fruit are not present.
• Minimize disturbance within miles of where this plant occurs, and anticipate wider occupation when plants are present before disturbance.
• Manual pulling and herbicide treatments are hindered by thorny branches.
• Manually pull new seedlings and tree wrench saplings when soil is moist, ensuring removal of all roots and wear eye protection during treatment.
• Burning treatments are suspected of having minimal topkill effect due to absence of litter fuel.
• Readily eaten by goats with potential spread of seed if browsed in spring.

Recommended control procedures

• Thoroughly wet all leaves with Garlon 3A and Garlon 4 as a 2-percent solution (8 ounces per 3-gallon mix). When nontarget damage is not a concern, use Arsenal AC* or Vanquish* as a 1-percent solution in water (4 ounces per 3-gallon mix) with a surfactant.
• For stems too tall for foliar sprays, apply a basal spray of Garlon 4 as a 20-percent solution (5 pints in a 3-gallon mix) or, where safety to surrounding vegetation is not a concern, Stalker* as a 6- to 9-percent solution (1.5 to 2 pints per 3-gallon mix). Mix either solution in a labeled basal oil product, vegetable oil or mineral oil with a penetrant, or fuel oil or diesel fuel (where permitted) (January to February or May to October).
• Cut large stems and immediately treat the stump tops with one of the following herbicides in water with a surfactant: Arsenal AC* as a 5-percent solution (20 ounces per 3-gallon mix) or when safety to surrounding vegetation is desired, a glyphosate herbicide as a 20-percent solution (5 pints per 3-gallon mix). ORTHO Brush-B-Gon, Enforcer Brush Killer, and Vine-X are effective undiluted for treating cut-stumps and available in retail garden stores (safe to surrounding plants).

* Nontarget plants may be killed or injured by root uptake.

Images

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April

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