Ground Rose

Coast Ground Rose
Rosa spithamea
NATIVE

Description (Jepson, PlantID.net)

• Eudicotyledon
  • Eudicots are a major lineage of flowering plants; see family for general characteristics
• Rose Family (Rosaceae)
• Low-growing deciduous small shrub
  • Spreads by rhizomes (horizontal underground stems)
• Stem with few to many prickles (extensions of the epidermis), which are straight or slightly curved
• Leaves
  • Compound (divided into leaflets)
  • 5-7 leaflets are glandular (sticky) with toothed edges
• Flowers
  • Inflorescence is a cyme (branched stem with flowers opening from the top down) with up to 10 flowers
  • Pink, 5-petaled, open-faced flower
    • Numerous stamens (male flower parts) and pistils (female flower parts)
    • 5 sepals (usually green, outer flower parts), sometimes glandular
      • Hypanthium (floral cup, formed from the fusion of petals, sepals, and stamens) is present
  • Pedicels (stalk of a single flower) and sepals (usually green, outer flower parts) generally with stalked glands
  • Ovary superior (above the attachment of other flower parts)
• Fruit is an aggregate of many achenes (single-seeded, dry fruits that do not split open)
  • Scarlet-colored, round floral cup (hypanthium), called a hip, encloses the seeds and remains on the plant throughout winter
  • Sepals are more or less erect and persist on fruit
• Height to 20 in.

Distribution

• Native to California
  • Grows in open forests and chaparral chaparral
  • See Calflora for statewide observations of this plant
• Outside California, grows in Oregon
• Grows at elevations between 490 and 5,090 ft.

Uses (San Mateo County Parks prohibits removal of any natural material)

• Wildlife
  • Dense, thicket-like growth provides protection and nesting habitat for birds and mammals
  • Plant structure and material are used by native bees for nesting
    • Some cavity-nesting bees, e.g. yellow-faced bees (Hylaeus species), nest in small hollow stems (Jordan 2020)
    • Leafcutter bees (Megachilidae) collect leaf material for nests – look for the half-moon cuts!
  • Flowers are a source of pollen for native bees and other insects
  • Larval food source (host) for butterflies, e.g. variable checkerspot (Euphydryas chalcedona), moths, and specialist bees (Jordan 2020)
  • Many species of gall (cynipid) wasps co-opt the DNA of Rosa species to create a unique home and food for their larvae in the form of a gall (Russo 2021)
    • Galls are abnormal, tumorlike growths induced by parasites (e.g. insects, mites, or bacteria)
  • Rose hips persist, providing food through the winter for squirrels, rabbits, and mice, and for fruit-eating birds, e.g. American robin (Turdus migratorius) and varied thrush (Ixoreus naeviu)
• Native people (for Rosa species)
  • Medicinal uses
    • Infusion of petals or buds used as an eye wash and to treat fevers in infants
    • Infusion of leaves used for intestinal ailments
    • Decoction of rose hips used to treat fever, colds, indigestion, rheumatism, and kidney ailments
  • Rose hips, a source of vitamin C and antioxidants, were eaten
  • Blossoms used to make a beverage
  • Stems used in basketry
• Rose hips are commonly used around the world to make essential oils, teas, jellies, jams, and wines

Name Derivation

• Rosa (RO-za) – from the Latin for “rose,” probably from the Greek rhodon, “rose”
• spithamea (spith-a-MEE-a) – from the Latin spithama, “a span,” traditionally equal to the distance between the first and last fingers of an outstretched hand, referring here to the dwarf nature of this species
  • Original description of R. spithamea by botanist Sereno Watson begins, “A span high,…” (Watson 1880, p. 444)

Notes

• Fire adapted (Ertter 2001)
  • Flowers are abundant for a few seasons following disturbance, especially fire, which not only removes the overstory, but also adds nutrient-rich ash
  • Without disturbance, flowers are sparse and plant persists vegetatively in the understory
• Leaves often turn bright red in fall (Ertter 2001)
• Wild roses (Rosa species), nightshades (Solanum species), California poppies (Eschscholzia species) are examples of plants with nectarless flowers that offer only pollen
  • Pollen provides no immediate energy, so bees foraging on these flowers must intermittently visit nectar-bearing plants to keep their sugar buzz (Thorp 2002)
• Simple petal arrangement is characteristic of wild roses
  • Most garden roses are double-flowered, meaning some stamens and pistils have been converted to petals
• Roses have prickles, rather than thorns or spines, which help deter herbivory
  • Prickles grow from the outer layers (epidermis) of plant stems, as on blackberries
  • True thorns are sharp-pointed modified stems, as on citrus trees and at Edgewood on chaparral pea (Pickeringia montana var. montana)
  • Spines are sharp-pointed modified leaves, as on cacti and at Edgewood on gooseberries, or leaf parts, as on leather oaks
• Many species of cynipid wasps can co-opt the DNA of Rosa species to create a unique home and food for their larvae in the form of a gall (Russo 2021)
• For an interesting discussion of the complex classification history of the Rosa genus, see Barbara Ertter’s Historical Background essay on the California rose (R. californica), where she writes,
  • “The reason for the tremendous uncertainty in the number of species of Rosa is largely because the genus refuses to resolve itself into a tidy set of unequivocal species, under any species concept.” (Ertter 2001)

ID Tips

• May be confused with two other species of roses at Edgewood, California rose (R. californica) and wood rose (R. gymnocarpa var. gymnocarpa)

	Ground Rose	Wood Rose	California Rose
Growth Habit	low growing, spreading	spreading	tall, thicket-forming
Height	≤ 1.6 ft.	≤ 3 ft.	≤ 8 ft.
Prickles	usually slender, straight or curved … ≤ 0.3 in. long	fine, straight … ≤ 0.3 in. long	thick-based, flat, often curved  … ≤ 0.6 in. long
Inflorescence	≤ 10 flowers	≤ 5 flowers	≤ 30 flowers
Sepals	persist in fruit	do not persist in fruit	persist in fruit
Hips (fruit)	glandular (sticky)	not glandular (sticky)	not glandular (sticky)
Best Trails	Live Oak	Lower Sylvan	…

At Edgewood

• Found in open woodlands and chaparral
  • Found in woodland area of Live Oak trail
  • See iNaturalist for observations of this plant
• Flowers May – August

Specific References

Breckling, B. 2008. Spring Wildflowers of Henry W. Coe State Park and the Inland San Francisco Bay Area. Pine Ridge Association.

Ertter, B. 2001. Rosa spithamaea. Native California Roses.

Jordan, S.F., J. Hopwood, and S. Morris. 2020. Nesting and Overwintering Habitat for Pollinators and Other Beneficial Insects. Xerces Society.

Russo, R. 2021. Plant Galls of the Western United States. Princeton University Press, Princeton, New Jersey.

Thorp. R., P. Schroeder, and C. Ferguson. 2002. Bumble bees: Boisterous pollinators of native California flowers. Fremontia 30(3-4): 26-31.

Watson, S. 1880. Botany, Vol.II. John Wilson and Son, University Press. Cambridge, Massachusetts. Biodiversity Heritage Library.

General References

Calflora Database. 2014. Berkeley, California.

Calscape. 2018. California Native Plant Society.

Charters, M.L. 2015. California Plant Names: Latin and Greek Meanings and Derivations.

Charters, M.L. 2017. Southern California Wildflowers: Guide to the Pronunciation of Specific, Generic and Family Names.

Corelli, T. 2004. Flowering Plants of Edgewood Natural Preserve (2nd. ed.). Monocot Press, Half Moon Bay, California.

Dave’s Garden.

Elpel, T.J. 2013. Botany in a Day: The Patterns Method of Plant Identification. HOPS Press, Pony, Montana.

Flora of North America. efloras.org.

Harris, J.G. and M.W. Harris. 2013. Plant Identification Terminology: An Illustrated Glossary. Spring Lake Publishing, Spring Lake, Utah.

Keator, G. 2009. California Plant Families. University of California Press, Berkeley and Los Angeles, California.

Native American Ethnobotany DB.

Regents of the University of California. Jepson eFlora. Jepson Herbarium. University of California, Berkeley.