CPC Plant Profile: Nuttall's Lotus
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Plant Profile

Nuttall's Lotus (Acmispon prostratus)

Photo Credit: Kier Morse
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: N/A
  • Family: Fabaceae
  • State: CA
  • Nature Serve ID: 139058
  • Date Inducted in National Collection: 06/01/2017

Acmispon prostratus is an annual herb found in coastal sand dune and sandy coastal sage scrub communities in San Diego County and neighboring Baja California, Mexico (CNPS 2017). This low-sprawling plant is characterized by flowers with bright yellow petals spotted with red (NatureServe 2016). As a result of habitat destruction and non-native invasive weeds, the species has been federally listed as critically imperiled since 1993, and is one of several sand dune plants that are facing extirpation in San Diego County.

Participating Institutions
Updates
  • 10/17/2020
  • Propagation Research

In 2016 San Diego Zoo Global made two seed collections from different populations on City of San Diego land. Germination trials of the seed showed that the collections were viable. Seed readily germinated, though it was not grown to maturity. I believe the species can be grown ex-situ, with subsequent seed collected and available for reintroduction or population augmentation.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, San Diego Zoo Global holds 4 accessions of Acmispon prostratus in orthodox seed collection. There are as many as 16591 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 2 accessions of Acmispon prostratus in orthodox seed collection. There are as many as 5009 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 08/05/2020
  • Seed Collection

Based on an August 2020 extract of the California Plant Rescue Database, California Botanic Garden has collected 2 seed accessions of Acmispon prostratus from 2 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 50 maternal plants

  • 08/05/2020
  • Seed Collection

Based on an August 2020 extract of the California Plant Rescue Database, San Diego Zoo Global has collected 4 seed accessions of Acmispon prostratus from 4 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 250 maternal plants

Joe Davitt
  • 08/17/2017

Population or occurrence counts have varied in the past 20 years. It is believed there are roughly 40 historic locations in the US (all in San Diego County), with the number of extant occurrences hovering around 30. There are 21 occurrences on conserved lands. Many populations have declined as a result of invasive non-natives. Because it is an annual, some years populations seem to be doing very well, and other years there might be no individuals in a population. Furthermore, it is difficult to track whether a decline in numbers is a result of a weed invasion, trampling, or simply rain and temperature conditions. As with all annuals, it is difficult to count individuals persisting in the soil seed bank, but eradication of invasives in some locations might lead to the augmentation of existing populations, or the reestablishment of extirpated populations.

Joe Davitt
  • 08/17/2017

Human activity has led directly to the massive decline of this species. Acmispon prostratus has evolved to live in coastal sand dunes, many of which have been developed in the past for homes or cleared for recreational beaches or parks. The species is now restricted to a few beach locations and ocean lagoons and bays. Development is not the major threat to remaining populations as these lands are under restrictions and any development projects would likely require major mitigation projects. Invasive plants and trampling by people and dogs remain the largest threat to the species. Sahara mustard (Brassica tournefortii) has been particularly harmful to some populations. Many invasive grasses do very well in sandy substrates, invasive Limonium species, Carpobrotus, etc. are all very harmful. Some populations are protected by federally listed California least tern nesting areas, which are fully fenced and well managed.

Joe Davitt
  • 08/02/2017

Invasive species removal is the most needed management action for this species. The species is a good candidate for seed bulking and reintroduction into suitable areas once weeds are under control. Furthermore, extant populations could be augmented with seed that has been bulked ex-situ.

Joe Davitt
  • 08/02/2017

Research into the natural soil seed bank of this species could help predict the likelihood of rediscovering extirpated populations.

Joe Davitt
  • 08/02/2017

In 2016 San Diego Zoo Global made two seed collections from different populations on City of San Diego land. Germination trials of the seed showed that the collections were viable. Seed readily germinated, though it was not grown to maturity. I believe the species can be grown ex-situ, with subsequent seed collected and available for reintroduction or population augmentation.

Nature Serve Biotics
  • 05/02/2017

Lotus nuttallianus is known from San Diego County, California and Baja California, Mexico. It is declining precipitously and is known from fewer than 26 extant occurrences in California. Land management activities, development and non-native plants are the major threats to this species.

Ryan Fitch
  • 04/12/2017

Current threats to this species include development, invasive plant species, trampling, dogs, and land management activities (particularly by the United States Navy at Silver Strand and Imperial Beach) (NatureServe).

Ryan Fitch
  • 04/12/2017

As of 2005, there are fewer than 26 extant occurrences in California (NatureServe).

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Photos
Nomenclature
Taxon Acmispon prostratus
Authority Greene
Family Fabaceae
CPC Number 2687
ITIS 820047
USDA
Common Names Nuttall's Lotus | Prostrate Lotus | wire bird's-foot trefoil
Associated Scientific Names Lotus nuttalianus | Acmispon prostratus | Hosackia prostrata
Distribution The only occurrences are found in San Diego County, California, and adjacent Baja California, Mexico.
State Rank
State State Rank
California S1
Habitat

This species can be found within coastal dune and [sandy] coastal scrub habitats (CNPS 2017).

Ecological Relationships

The species occurs on a rare habitat type and has a restricted range. Other species sharing this specialized habitat include Abronia umbellata, Abronia maritima, Camissoniopsis cheiranthifolia, Ambrosia chamissonis, Nemacaulis denudata, etc. Pollinator studies show a wide range of floral visitors from various bee, beetle, and butterfly genera, though no confirmed pollination has been recorded.

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Leaf-cutting bees Megachile rotunda Not Specified Link
Leaf-cutting bees Megachile gentilis Not Specified Link
Leaf-cutting bees Megaghile brevis onubrychia Not Specified Link
Leaf-cutting bees Megaghile brevis onubrychia Not Specified Link
Leaf-cutting bees Anthidium collectum Not Specified Link
Leaf-cutting bees Anthidium collectum Not Specified Link
Leaf-cutting bees Anthidium collectum Not Specified Link
Leaf-cutting bees Anthidium utahanse Not Specified Link
Leaf-cutting bees Osmia bruneri Not Specified Link
Anthophorine bees Anthophora urbana Not Specified Link
Leaf-cutting bees Osmia calla Not Specified Link
Leaf-cutting bees Osmia exigua Not Specified Link
Leaf-cutting bees Ashmeadiella californica californica Not Specified Link
Leaf-cutting bees Osmia exigua Not Specified Link
Sweat bees Augochlorella pomoniella Not Specified Link
Leaf-cutting bees Osmia gabrielis Not Specified Link
Bumble bees Bombus caliginosus Not Specified Link
Leaf-cutting bees Osmia juxta Not Specified Link
Bumble bees Bombus vosnesenskii Not Specified Link
Leaf-cutting bees Osmia kincaidii Not Specified Link
Leaf-cutting bees Osmia kincaidii Not Specified Link
Leaf-cutting bees Osmia nemoris Not Specified Link
Leaf-cutting bees Osmia nemoris Not Specified Link
Leaf-cutting bees Hoplltis sambuci Not Specified Link
Leaf-cutting bees Osmia nigrifrons Not Specified Link
Leaf-cutting bees Osmia nigrifrons Not Specified Link
Leaf-cutting bees Osmia nigrifrons Not Specified Link
Leaf-cutting bees Osmia nigrifrons Not Specified Link
Leaf-cutting bees Osmia Not Specified Link
Leaf-cutting bees Pegachile parallela facunda Not Specified Link
Sweat bees Sphecodes Not Specified Link
Long-horned bees Synhalonia actuosa Not Specified Link
Butterflies & Moths
Blues Plebejus acmon Not Specified Link
Skippers Polites sabuleti Not Specified Link
Skippers Pyrgus cummunis Not Specified Link
Beetles
Leaf beetles Acanthoscelides fraterculus Not Specified Link
Jewel beetles Acmaeodera angelica Not Specified Link
Jewel beetles Acmaeodera feneysi Not Specified Link
Jewel beetles Agrilus sierrae Not Specified Link
Flower beetles Mordella atrata albosuturalis Not Specified Link
Flower beetles Mordella hubbsi Not Specified Link
Weevils Apion Not Specified Link
Lady beetles Coccinella trifasciata juliana Not Specified Link
Leaf beetles Diachus auratus Not Specified Link
Lady beetles Hippodamia convergens Not Specified Link
Leaf beetles Pachybrachys hybridus Not Specified Link
Leaf beetles Pachybrachys signatifrons Not Specified Link
Checkered beetles Phyllobaenus scaber Not Specified Link
Leaf beetles Saxinis saucia Not Specified Link
Checkered beetles Trichodes ornatus Not Specified Link
Flies
Syrphid flies Paragus Not Specified Link
Other
Potter wasps Leptochilus menkei Not Specified Link
Plant bugs Lopidea Not Specified Link
Omalus granti Not Specified Link
Psenelus Not Specified Link
Potter wasps Stenodynerus blandus Not Specified Link

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