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

See General References

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.