Franciscan Onion

Franciscan Onion © DSchiel

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)

  • Host plant for the larvae of several moth species, including the alfalfa looper moth (Autographa californica)
  • Pollinated by insects
  • Native people had many uses for onions (Allium species)
    • Ate the bulbs boiled, steamed, roasted, or baked in earthen ovens
    • Ate fresh stems and leaves (Anderson 2005)
    • Used bulb as an analgesic for insect stings and bites
    • Made a syrup from plant juice to treat colds and throat irritations

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, and rhizomes, are 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)

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 (L), Three-cornered Leek (LM), Franciscan Onion (RM), Ithuriel’s Spear (R)
© KKorbholz (L), AFengler (LM), DSchiel (RM, R)
Pitted OnionThree-cornered LeekFranciscan OnionIthuriel’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 Colorwhite or pale pink with dark midveinswhite with green midveinsmagenta with recurved petal tipsblue-purple with dark midveins
Edgewood Habitatserpentine outcropsdisturbed areas (i.e.main entrance)north-facing woodlandswoodlands and grasslands
¹ Pedicel: stalk of a single flower

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: 85-104.

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