Creeping Oregon grape | |
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Berberis repens | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Order: | Ranunculales |
Family: | Berberidaceae |
Genus: | Berberis |
Species: | B. repens
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Binomial name | |
Berberis repens | |
Synonyms [2] | |
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Berberis repens commonly known as creeping mahonia, creeping grape holly, or creeping barberry, is a species of Berberis native to most of the western United States and two western provinces of Canada. It has found use as a xeric ornamental plant and has escaped from cultivation in areas beyond its native range.
Berberis repens is an extremely short shrub, usually just 2–20 centimeters tall, very occasionally reaching 60 centimeters. The bark on stems becomes gray-purple or gray in color and are not hairy. [3] The plants spread by modified underground stems ( rhizomes) that are about 1.5–5.0 centimeters under the surface of the mineral soil. [4] [5] Despite the short above ground height its roots can reach as much as three meters into the ground. [6]
The leaves are compound with an odd number of leaflets attached to the main vein. Usually leaves have five or seven leaflets, but may have just three. The length of a complete leaf structure will be 10–30 centimeters. The upper surfaces of the leaflets are smooth and dark green while the undersides are lighter green and covered in fine, downy hairs. [7] The edges of the leaflets have between six and twenty-four teeth tipped with spines. [3] Although it is evergreen, in the fall and winter leaves will partially or completely turn bronze or red in color when exposed to sun. [8]
The flowers grow in a densely packed inflorescence without branches called a raceme. Each one will have between ten and fifty flowers and be 4–10 centimeters long. [7] [3] The yellow flowers bloom early in the spring and are quite fragrant. [4] Local condition determine the exact timing of the bloom which may be as early as February or as late as June. [9] [3] The flowers have six yellow sepals outside the six yellow petals with the tip of each split. Each flower has a single pistil, but six pollen producing stamens which emerge when the petals or sepals are touched. [10]
Berberis repens has quite striking dark purple-black berries with a matte blue blush that contain a single seed and resemble a grape. [10] Each berry is roughly round, about 6–10 millimeters in size, and juicy in texture. [3] The flavor of the berries is quite tart with an astringent quality, and generally more attractive to birds than humans. [9]
Berberis repens was scientifically described by John Lindley in 1828. Two years later George Don published a descriptoin of it classifying it as Mahonia repens. [2] The correct classification of this and the other species into a separate Mahonia genus or with the rest of the barberries in Berberis has been controversial since that time. [11] In 1997 a widely cited paper by Joseph Edward Laferrière summarized the arguments in favor of Berberis as the correct classification. [12] Though genetic work since that time has argued for the revival of at least part of the genus. [13]
Some botanical sources, such as the USDA Natural Resources Conservation Service PLANTS database (PLANTS), continue to list the species as Mahonia repens. [14] However, as of 2024 Plants of the World Online, [2] World Flora Online, [15] and NatureServe [1] agree that it is properly placed in Berberis. Additionally, some botanists treat the plant as a subspecies of Oregon-grape holly (Berberis aquifolium), in which case the scientific name Berberis aquifolium var. repens is applied. [16]
The species name, repens, is Latin for "creeping". [17] Berberis repens is commonly known as "creeping grape holly", [8] "creeping grapeholly", [18] "creeping mahonia", [19] "creeping barberry", [20] and "creeping Oregon grape". [21]
It is native to the botanical continent of Northern America. In Canada its range is the southern parts of the provinces of Alberta and British Columbia. [22] [23] [24] In the United States it is found throughout the west from Washington (state) to California and eastwards to Montana to New Mexico including all the states between. East of the Rocky Mountains it is also found in the US states of Texas, North Dakota, South Dakota, Nebraska, and Minnesota. [14] [2]
It has also been found as an introduced species in Ontario, Canada and Hungary in the European Union. [22] [2] NatureServe also lists it as introduced to the US states of Pennsylvania and Delaware. [1]
It is widespread, and found at low to mid elevation on dry plateaus, in forests and on foothills. [21] The plant grows at elevations from 150 metres (490 ft) to 3,000 metres (9,800 ft). [16] [3]
The NatureServe conservation status for the species is "Globally Secure" G5 as evaluated in 2015. Though it is "Critically Imperiled" at the state or province level (S1) in Saskatchewan and Texas, "Imperiled" (S2) in North Dakota, and "Vulnerable" (S3) in Alberta. [1]
Creeping grapeholly generally increases in response to disturbances in forest ecosystems such as mild fires, severe fires, and logging, [25] though it may be eliminated in the short term by severe intensity fires. [5] As a long lived plant with a protected root system and seeds that are presumed to persist in the soil it recovers quickly from low intensity fires. [25] The above ground stems and parts of the plant in the forest humus are vulnerable to fire damage, but resprouts from undamaged rhizomes in the mineral soil. [5] It decreases over time when the forest canopy is too dense, though it can tolerate significant shade and increases as other plants are negatively impacted by acidification of the soil by conifer trees. [25]
Elk and white tailed deer both consume creeping grapeholly in the winter, and to a greater extent when the weather is mild and there is less snow cover burying the plants, though it is not a large portion of their diets. [26]
The berries are edible but are considered bitter, [21] and used to make jellies. [19] [21]
The Tolowa and Karok Indians of Northwest California used the roots for a blood and cough tonic. The Hopi, Paiute, Navajo, Shoshoni, Blackfoot, Cheyenne, Mendocino, and other tribes also used the plant for medicinal, food, and ceremonial needs. [27] Native Americans also used the wood of the stem to produce yellow dyes [19] to stain woven baskets. [21]
Creeping grapeholly is cultivated as an ornamental plant for use in natural landscaping, and in water conserving, drought tolerant, traditional residential, native plant habitat, and wildlife gardens. [19] It is a low water ground cover and is used in gardens under oaks to reduce or eliminate irrigation that can threaten mature trees. [28] Berries and foliage are resistant to browsing by deer. [18] Because of its spreading habit it is used to control erosion in dry areas. [10] It is the very deep and extensive root system that gives the plants their adaptation to low water conditions. [25]
Plants require well drained soil and prefer a soil pH 5.5 to 7.0, but will tolerate 4.5 to 7.5. In winter the leaves may be scalded by excessive sun especially in combination with dry winds. [10] Sources differ on the winter hardiness of creeping grape holly. In their book Nora Harlow and Saxon Holt list USDA zones 4–10. [29] Similarly the North Carolina Extension lists the range as 4b–9b. [18] However, the Missouri Botanic Garden lists a narrower range of just zone 5–8. [19]
It is a year-round attractive, hardy plant, tolerant of drought, frost, and heat, so it is popular with landscape designers and gardeners. It can provide good ground cover in a cold situation. In garden conditions, and where their ranges overlap in nature, this species hybridizes readily with Oregon-grape (Mahonia aquifolium), and the hybrids are less prostrate in their habit than the pure stock.[ citation needed]