Franciscan Onion

San Franciscan Onion
Allium peninsulare var. franciscanum
NATIVE – CA ENDEMIC

Description (Jepson, PlantID.net)

• Monocotyledon
  • Monocots are a major lineage of flowering plants; see family for general characteristics
• Onion Family (Alliaceae)
• Perennial herb
  • Grows from a bulb (short underground stem with fleshy leaves, e.g. onion)
• Stem is a scape (leafless stem rising from ground level)
• Leaves
  • 2-3 long, slender, and curved (≤ 2 ft.), growing from stem base (basal) 
  • Channeled, with deep longitudinal grooves, or cylindrical
  • Usually wither before flowers open
• Flowers
  • Inflorescence (flower arrangement) is an open umbel (a spoke-like flower cluster with stalks radiating from a single point) of 5-35 flowers at the end of a long, leafless stalk (scape)
    • 2 fused bracts (modified leaves at base of inflorescence) become pale and papery with age
  • Each magenta flower has 3 petals and 3 sepals (outer flower parts), in 2 separate whorls, similar in appearance and collectively called tepals
    • Tepal tips are more-deeply colored, pointed, and recurved
    • Ovary superior (above the attachment of other flower parts)
• Fruit is a capsule (a dry, multi-chambered fruit that splits open at maturity) with small black seeds
• Height to 18 in.

Distribution

• Native and endemic (limited) to California
  • Grows in woodland, valley and foothill grasslands
  • 50-54% of plants occur on ultramafic soils, e.g. serpentine; see ultramafic affinity rankings (Calfora per Safford and Miller 2020)
  • See Calflora for statewide observations of this plant
• California Rare Plant Rank: 1B.2 (rare, threatened, or endangered in California and elsewhere)
• Grows at elevations to 1,000 ft.

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

• Wildlife
  • Larval food source (host) for several moth species, e.g. alfalfa looper moth (Autographa californica)
  • Pollinated by insects
• Native people (for Allium species)
  • Ate the bulbs boiled, steamed, roasted, or baked in earthen ovens
  • Ate fresh stems and leaves (Anderson 2005)
  • Bulbs used as an analgesic for insect stings and bites
  • Syrup from plant juice used to treat colds and sore throat
  • See Onion/Garlic Family (Alliaceae) for more details about how Native people actively managed edible geophytes

Name Derivation

• Allium (AL-ee-um) – from the Latin for “garlic”
• peninsulare (pen-in-soo-LARE-ee) – referring to the species Allium peninsulare having been first collected in Baja California, a peninsula
• franciscanum (fran-cis-can-um) – referring to the San Francisco peninsula, where this variety primarily grows

Notes

• Geophytes (e.g. plants growing from bulbs, corms, rhizomes, or enlarged taproots) are well adapted to survive fire, our Mediterranean climate’s long, dry summers, and extended droughts
  • Above-ground growth dies back after flowering, while underground the plant survives with stored water and nutrients
• Leaves have an oniony smell
• Variously placed in other monocot families in the past, including the Lily family (Liliaceae) and, currently, the Amaryllis family (Amaryllidaceae)
• Edgewood’s Franciscan onion is classified as a variety
  • Variety indicates a population with small morphological variations, e.g. color, seen throughout the geographic range of the species; interbreeding is possible
  • Subspecies indicates a geographically-separated population with distinct morphological characteristics; when not isolated, interbreeding is possible
  • In practice, botanists have not consistently applied these ranks

ID Tips

• May be confused with 2 other commonly-seen onions (Allium species) at Edgewood – pitted onion (A. lacunosum var. lacunosum) and the non-native three-cornered leek (A. triquetrum) – and with Ithuriel’s spear (Triteleia laxa) in the Brodiaea family
  • Of these, only Franciscan onion has magenta petals with recurved tips

	Pitted Onion	Three-cornered Leek	Franciscan Onion	Ithuriel’s Spear
Stem Height	≤ 14 in.	≤ 16 in.	≤ 18 in.	≤ 28 in.
Pedicel Length¹	≤ 0.5 in.	≤ 1 in.	≤ 0.8 in.	≤ 4 in.
Flower Color	white or pale pink with dark midveins	white with green midveins	magenta with recurved petal tips	blue-purple with dark midveins
Edgewood Habitat	serpentine outcrops	disturbed areas (i.e.main entrance)	north-facing woodlands	woodlands and grasslands

At Edgewood

• Found in north to northwest facing woodlands
  • No iNaturalist observations are documented because locations of rare species are obscured
• Flowers April – May

Specific references

Alexander, E.B. 2010, Oct. and 2011, Jan. Serpentine soils and why they limit plant survival and growth. Fremontia 38/39: 28-31.

Anderson, M.K. 2005. Tending the Wild. University of California, Berkeley.

Safford, H.D., and J.E.D. Miller. 2020. An updated database of serpentine endemism in the California flora. Madroño 67(2): 85-104. BioOne Complete. PDF hosted by San Diego State University, San Diego, California.

Safford, H.D. 2010, Oct. and 2011, Jan. Serpentine endemism of the California flora. Fremontia 38/39: 32-39.

General References

Calflora Database. 2014. Berkeley, California.

Calscape. 2018. California Native Plant Society.

Charters, M.L. 2015. Latin and Greek Plant Names: Meaning 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.