Desert organisms live poised to take advantage of any sudden rainfall—and so do the scientists who study them. So when it was predicted in the fall of 2009 that Hurricane Jimena would cut across the peninsula of Baja California, bringing rain to the Vizcaíno Desert, researchers sprang into action to organize an expedition.

Four wheel-drive vehicle almost over-topped by the lush annual plants
responding to the hurricane’s rainfall south of Laguna San Ignacio.

Background There are few places in peninsular California where water availability is more erratic than the Vizcaíno Desert. Like southern California, the Central Desert to the north of the Vizcaíno region is more predictably influenced by winter rainfall, while the arid regions south of the Vizcaíno region are influenced by summer and fall tropical storms and hurricanes. Located between these areas of reliable, if sparse, precipitation the Vizcaíno region’s pattern is unpredictable. It may receive winter rains, or may be subject to hurricanes, or may receive no measurable rainfall at all for several consecutive years. Summer and fall season precipitation is particularly rare in the Vizcaíno Desert. In the last 60 years, only eight hurricanes have passed through the region. For comparison, the considerably smaller Cape region of Baja California Sur (BCS) has experienced sixteen hurricanes in the same period.

Expedition area.

On September 2, 2009, Hurricane Jimena made landfall near San Juanico, dropping flooding rains in the southern portions of the Vizcaíno Desert from San Ignacio Lagoon southward. Hurricane Jimena was a critical resource pulse for a region which has not been directly hit by a hurricane since Hurricane Lester in 1992. Because this desert is remote from collections-based institutions, the historical collection effort has been modest compared to other ecoregions in the peninsula. Furthermore, a query of regional herbaria suggests that less than 10% of botanical collections in the area came within three months following a hurricane. This hurricane provided an opportunity to generate important and rarely collected data on the response of species in the area to large pulses of precipitation.

Goals Collections from a biologically rich place. The focus area of the expedition was a transition area between the Vizcaíno Desert, La Giganta Ranges, and the Magdalena Plains. The area is accepted to be floristically rich, with 496 known plant species (39 of them endemic) in the El Vizcaíno Biosphere Reserve. However for many of these species we know little about their abundance and distribution. For instance, Arida crispa, Viscainoa geniculata var. pinnata, and Eriogonum repens are all endemic taxa, known only from a few specimens in the proposed expedition area. A principal goal of the expedition was to make ample collections of plants and invertebrates, to be identified and deposited within the participating institutions.

Providing information to researchers and to the public. There was little doubt that this expedition would result in novel distributional data valuable to the understanding of the natural history and conservation of the peninsula of Baja California. An important goal of the expedition was to photodocument visited sites with gigapixel panoramas and to create a web-based resource that summarizes the expedition findings and points users to detailed data and photographic documentation.

Campsite at San José de Gracia, BCS

Participating institutions
  • Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, BCS
        Dr. José Luis León de la Luz, Curator of HCIB Herbarium
  • San Diego Natural History Museum (SDNHM), San Diego, CA
        Dr. Jon Rebman, Curator of Botany
        Dr. Michael Wall, Curator of Entomology
  • Universidad Autónoma de Baja California (UABC), Ensenada, BC
        Dr. José Delgadillo, Curator of BCMEX Herbarium

Funding The field expenses for this post-hurricane expedition and the creation of this website associated with the trip was graciously funded by the JiJi Foundation. We are grateful for their support of natural history research on the Baja California peninsula.

Interactive map of survey area with georeferenced and embedded field photos from expedition.

The Field Expedition The field collecting activities for the post-hurricane Jimena expedition were conducted on 16-22 October 2009. During this plant surveying and collecting trip, 257 herbarium specimens were collected. The first set of plant specimens collected by Rebman and Delgadillo are deposited in the SD Herbarium at the San Diego Natural History Museum and duplicate specimens (when available) are deposited in the BCMEX and HCIB herbaria in Baja California and Baja California Sur, respectively. Specimens made by León de la Luz are deposited in the HCIB Herbarium in La Paz with duplicates (when available) to be deposited in the SD Herbarium.
Many different people participated in this expedition including scientists, conservationists, university students, and local natural history guides from the San Ignacio area. This trip also provided a unique opportunity for three of the botanists that curate major herbarium collections of Baja California specimens to get together and work in the field collaboratively. Dr. Michael Wall, the SDNHM Curator of Entomology, also joined the botanists in the field during this expedition. Dr. Wall collected many different insect and other arthropod specimens and provided a lot of knowledge about plant-insect interactions.







Botanical Results
New Plant Records During the post-hurricane expedition, we documented three plant taxa that have never previously been collected in the state of Baja California Sur and are thus new plant records for this state.

Portulaca halimoides

These include: Amaranthus crassipes (Amaranthaceae), Eragrostis barrelieri (Poaceae), and Portulaca halimoides (Portulacaceae). Amaranthus crassipes is native annual that was not known previously from anywhere in either BC or BCS. The closest known locale for this species to our region is Arizona. Interestingly, we documented 6 different species in the genus Amaranthus during this trip. Eragrostis barrelieri (Poaceae) is a non-native annual species that was not known previously from anywhere in either BC or BCS. This specimen was found near a dirt road and it is likely that it came in on a car tire. This weedy species is known to occur readily in disturbed areas of California. Portulaca halimoides is a native annual that was previously known from northwestern BC. This species does occur in the Sonoran Desert and disjunctly to Central America and South America, but was not previously documented in BCS.

Specimen voucher-based checklist of the vascular plants of the San Ignacio — San Juanico Corridor with linked photographs and digital specimen scans for each taxon.

Distribution Data Many plant species that we documented during this expedition were found to be at or very near their northern range of distribution in the Baja California region. Thus, these species are mostly either more tropical in origin or are associated with summer rainfall regimes in the southern part of the peninsula. These include:

•	Asteraceae	Pluchea symphytifolia	Marina evanescens
•	Boraginaceae	Heliotropium procumbens
•	Convolvulaceae	Cuscuta odontolepis
•	Convolvulaceae	Cuscuta tuberculata
•	Euphorbiaceae	Euphorbia dentosa
•	Euphorbiaceae	Jatropha vernicosa
•	Fabaceae	Caesalpinia arenosa
•	Fabaceae	Indigofera suffruticosa
•	Fabaceae	Marina chrysorhiza
•	Fabaceae	Marina evanescens
•	Fabaceae	Marina vetula
•	Hydrophyllaceae	Nama coulteri
•	Hydrophyllaceae	Phacelia scariosa
•	Poaceae	Eriochloa acuminata var. acuminata
•	Poaceae	Leptochloa viscida
•	Poaceae	Panicum alatum
•	Poaceae	Sporobolus pyramidatus

Various species that we documented during this expedition were found to be at or very near their southern range of distribution in the Baja California region. Thus, these species are mostly either more temperate in origin or are associated with winter rainfall regimes in the northern part of the peninsula. These include:

•	Asteraceae	Ambrosia pumila
•	Asteraceae	Bahiopsis microphylla
•	Cactaceae	Cylindropuntia bigelovii
•	Lamiaceae	Teucrium glandulosum
•	Malvaceae	Horsfordia newberryi

Regional Endemics Our collection activities during this expedition documented many plant species that are regional endemics to this portion of the Baja California peninsula. Most of these species are endemic to southern BC and central to northern BCS and our specimen collections will help to better understand the distribution of these endemic species in our region.

•	Asteraceae	Amauria brandegeana	Camissonia sceptrostigma
•	Asteraceae	Ambrosia bryantii
•	Asteraceae	Bahiopsis chenopodina
•	Asteraceae	Encelia palmeri
•	Asteraceae	Encelia ventorum
•	Boraginaceae	Cryptantha angelica
•	Chenopodiaceae	Atriplex magdalenae
•	Convolvulaceae	Ipomoea jicama
•	Fabaceae	Marina peninsularis
•	Fabaceae	Senna confinis
•	Onagraceae	Camissonia sceptrostigma
•	Pteridaceae	Cheilanthes brandegeei
•	Zygophyllaceae	Fagonia villosa

Arida crispa

New Data on Rare, Locally Endemic Plants During this botanical expedition, we made a few collections of plant taxa that are very rare in the region and only occur in the local area where we were surveying. The rare, locally endemic plants that we encountered during this post-hurricane trip include: Arida crispa (Asteraceae), Burroughsia fastigiata (Verbenaceae), and Viscainoa geniculata var. pinnata (Zygophyllaceae). Arida crispa (Asteraceae) is a native herbaceous perennial that is only known from a few historical specimen collections in the vicinity of San Ignacio and near Canipolé in the Sierra de La Giganta. This species seems to be very rare and has an extremely limited distribution. We collected and photographed this rare species near Rancho San Zacharías between the town of San Ignacio and Laguna San Ignacio.

Burroughsia fastigiata

Burroughsia fastigiata (Verbenaceae) is a native woody subshrub with attractive whitish flowers that grows in scattered populations along the western side of the peninsula from near the BC/BCS border south to the Magdalena Plains. We collected and photographed this rare species in a couple of different populations in the area that we surveyed. According to where we found it growing during this trip, this species seems to only grow in alkaline soils that occur at the edge of dry or seasonally dry pools or lake beds on volcanic mesas.

Viscainoa geniculata var. pinnata

Viscainoa geniculata var. pinnata (Zygophyllaceae) is a rare endemic variety with odd-pinnate leaves that only occurs on the west side of the peninsula in northwestern BCS near San José de Gracia. The genus Viscainoa is monotypic with only V. geniculata and it is a near-endemic to the Baja California region, but is rather widespread as variety geniculata occurs from the southern San Felipe Desert of BC south to the Cape region, and also near Guaymas in Sonora. However, variety pinnata has only been collected a few times and seems to have a very limited range of distribution. During the expedition, we collected and photographed this rare variety in two different populations.

Notholaena standleyi

Rarely Collected Species in Baja California Sur Some of our specimens represent collections of species that are rarely documented in the Baja California region. These include:

•	Apiaceae	Hydrocotyle verticillata
•	Asteraceae	Flaveria trinervia
•	Asteraceae	Laennecia coulteri
•	Malvaceae	Malvastrum bicuspidatum ssp. bicuspidatum
•	Poaceae	Sporobolus cryptandrus
•	Pteridaceae	Notholaena standleyi

Euphorbia ceroderma

Interesting Collections A few of our specimen collections from this expedition represent interesting hybridization events or unusual distributions. For example, we collected Encelia ×laciniata (Asteraceae) which is a common interspecific hybrid that occurs between E. palmeri and E. ventorum, both regionally endemic plant species. This hybrid usually occurs on the edges of sand dunes in intermediate habitats because E. ventorum is a dune species that likes open sandy substrates and E. palmeri prefers harder soil substrates. We also collected a specimen of Encelia aff. palmeri that had narrower leaves and lacked the truncate leaf base normally found in E. palmeri. This specimen may represent a hybrid with another species of Encelia or an extreme variation in leaf type for E. palmeri. During our trip, we also collected Euphorbia ceroderma (Euphorbiaceae), which is a native stem succulent shrub. This species has a very interesting distribution because it is known from the west-central part of BCS and also from western Sonora, but with no populations in between. This type of disjunct range is very unusual for plants in our region. The population of this species that we collected on the expedition represents the northwestern-most distribution of this species in BCS.


See more Gigapan photos from the expedition.