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Montana Field Guide

Montana Field Guides

Myrtle Spurge - Euphorbia myrsinites
Other Names:  Donkey-tail Spurge, Creeping Spurge, Blue Spurge, Tithymalus myrsinites

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Non-native Species

Global Rank: GNR
State Rank: SNA
(see State Rank Reason below)
C-value:


Agency Status
USFWS:
USFS:
BLM:


 

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State Rank Reason (see State Rank above)
Euphorbia myrsinites grows in gardens of urban landscapes in various locations of Montana. This plant was introduced for cultivation into many portions of the USA and Canada (Riina, Geltman, Peirson, and Berry in Flora of North America (FNA) 2016). In Montana it became a trendy garden plant in the 2000s. As a preventative measure Beaverhead County placed it on their county noxious weed list [https://beaverheadcounty.org/departments/weed-district/] because in some states it has locally escaped from cultivation (Riina, Geltman, Peirson, and Berry in FNA 2016). As of 2021 escapes of Euphorbia myrsinites into urban-wildland environments have not been documented in Montana. A conservation status rank is not applicable (SNA) because the plant is exotic (non-native) in Montana and is not a suitable target for conservation activities.

NOTE: Any observation of Euphorbia myrsinites growing in a native or natural habitat in Montana should be reported to the appropriate County Weed Coordinator.
 
General Description
PLANTS: Herbaceous plants that are usually perennial, but sometimes biennial. Stems are succulent, erect to trailing, branched or unbranched, and 15-40 cm tall. Plants grow from a taproot. They produce a white, milky sap which is toxic if ingested. Source: Riina, Geltman, Peirson, and Berry in FNA 2016

LEAVES: Succulent (fleshy) leaves are alternate on the stem, glabrous, and appear veinless. Leaf stem (petiole) is absent or up to 2 mm long. Blades are obovate, obovate-oblong, lanceolate, orbiculate, or suborbiculate in shape, 2-30 mm x 3-17 mm. Leaf base is truncate or attenuate. Leaf margins are entire or finely denticulate. Leaf apex is acute to obtuse with an abrupt point (cuspidate or mucronate). Source: Riina, Geltman, Peirson, and Berry in FNA 2016

INFLORESCENCE: A terminal umbel of yellow-green, ovate bracts containing inconspicuous flowers that lack petals and sepals. The bracts are 2-12 mm long. Above the bracts, the true flowers are green and occur within a cup-like involucre called a cyathium (plural is cyathia). Each cyathium usually contains two seed (female) flowers and 6-12 (male) pollen flowers. Glands with horns are thick with rounded, dilated tips, 0.5-0.9 mm. Fruit is a capsule, more or less globose, unlobed, smooth, and 5-7 mm. Source: Riina, Geltman, Peirson, and Berry in FNA 2016

Phenology
Plants flower and fruit from spring to summer (Riina, Geltman, Peirson, and Berry in FNA 2016).

Diagnostic Characteristics
Myrtle Spurge is glaucous blue with an interesting architectural shape (Mahr 2009). Trailing stems spiral with a density of closely-set leaves; each leaf is waxy, fleshy, and pointed (Mahr 2009).

Range Comments
Plants are found in gardens through much of Canada and the USA.

The distribution in the FNA includes: British Columbia, Washington, Oregon, California, Idaho, Montana, Wyoming, Utah, Colorado, and New Mexico (Riina, Geltman, Peirson, and Berry in FNA 2016). It is assumed that FNA's distribution is based on herbarium specimens that document where the plant has escaped into more natural habitats; however, the source information for Montana could not be found. Because Myrtle Spurge has not been documented in Montana within natural or native habitats, MTNHP has not developed a range map.


Observations in Montana Natural Heritage Program Database
Number of Observations: 1

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Myrtle Spurge is found in gardens and yards; however, in some areas of the US and Canada plants have escaped cultivation. In many western states and provinces of Canada, Myrtle Spurge has been found in scrub-oak communities, open ground near forests, and shrub-steppe areas (Riina, Geltman, Peirson, and Berry in FNA 2016). It also has been found on dry gravelly or sandy soil of roadsides and disturbed areas (Giblin et al. [eds.] 2018).

In garden settings plants prefer hot, dry sites, although it will grow in almost any sunny area (Mahr 2009). It is drought tolerant and does well in poor, rocky soil (Mahr 2009).

Any observation of Euphorbia myrsinites growing in a native or natural habitat in Montana should be reported to the appropriate County Weed Coordinator.

Ecology
PLANT GROWTH
Plants can tolerate cold winters (Riina, Geltman, Peirson, and Berry in FNA 2016). In harsh weather leaves die back to the root crown (Mahr 2009). In milder climates plants can become evergreen (Mahr 2009).

INSECTS & PATHOGENS
Myrtle Spurge has few pest problems (Mahr 2009). Sometimes aphids, mealybugs, bacterial rot, or fungal rot can impact plants, especially in moist conditions (Mahr 2009).

Reproductive Characteristics
SEEDS
Seeds are brownish to gray, oblong, vermiculate-rugose on surface, and 2.8-4.5 by 2-3.2 mm (Riina, Geltman, Peirson, and Berry in FNA 2016).

LIFE CYCLE
Flowers are born on second year growth (Mahr 2009).

Myrtle Spurge easily reseeds and can be an aggressive plant. If plants are not dead-headed they can become dominant, especially during favorable conditions.

Management
To prevent re-seeding or invasion, plants should be dead headed before seeds mature (Mahr 2009). Seedlings can be pulled or hoed to reduce populations (Mahr 2009). Larger plants are more difficult to remove or thin (Mahr 2009).

Like most members of the Spurge (Euphorbiaceae) Family, plants produce a milky-white sap which is poisonous if ingested (Mahr 2009). Externally the sap can cause minor skin irritations or severe dermatitis in susceptible individuals. Always wear gloves when handling plants. If any sap touches the skin, wash immediately. Be especially careful when working with this plant to avoid getting sap into cuts or one's eyes.

References
  • Literature Cited AboveLegend:   View Online Publication
    • Flora of North America Editorial Committee, eds. 2016. Flora of North America north of Mexico, Vol. 12. Magnoliophyta: Vitaceae to Garryaceae. Oxford University Press, Inc. New York.
    • Hitchcock, C.L. and A. Cronquist. 2018. Flora of the Pacific Northwest: An Illustrated Manual. Second Edition. Giblin, D.E., B.S. Legler, P.F. Zika, and R.G. Olmstead (eds). Seattle, WA: University of Washington Press in Association with Burke Museum of Natural History and Culture. 882 p.
    • Mahr, Susan. 2009. Euphorbia myrsinites-Horticulture information from Wisconsin Master Gardener website. May 4th. University of Wisconsin.
  • Web Search Engines for Articles on "Myrtle Spurge"
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Citation for data on this website:
Myrtle Spurge — Euphorbia myrsinites.  Montana Field Guide.  .  Retrieved on , from