CPC Plant Profile: Arizona Cliffrose
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Plant Profile

Arizona Cliffrose (Purshia subintegra)

The Arizona cliffrose produces beautiful white flowers with exserted yellow stamen. Photo Credit: Joyce Maschinski
Description
  • Global Rank: G2 - Imperiled
  • Legal Status: Federally Endangered
  • Family: Rosaceae
  • State: AZ
  • Nature Serve ID: 148380
  • Date Inducted in National Collection: 04/04/1991

Arizona cliffrose, Purshia subintegra (Kearney) Henrickson is a xeric rosaceaeous evergreen shrub with pale yellow flowers and entire leaves that lack glands. Usually less than 2 m tall, it is closely related to Purshia stansburiana, a widespread species that has lobed leaves with glands and stalked glands on the hypanthium. Known from four disjunct populations in central Arizona, P. subintegra usually occurs on lacustrine outcrops, which have a distinct chalky white appearance. The largest population occurs in the Verde Valley, where a Pliocene limestone deposit called the Verde Formation forms finger-like protrusions into the basin (Phillips et al. 1996).

Participating Institutions
Updates
Center for Plant Conservation
  • 11/25/2021
  • Reintroduction

The largest and most fecund population of the endangered Purshia subintegra is restricted to limestone mesas in Verde Valley, Arizona, USA, where habitat destruction is imminent. To examine factors limiting its distribution and potential for expansion, we compared recruitment and survival of seedlings growing in soils from occupied and unoccupied habitat in caged field experiments and compared survival of caged and wild seedling cohorts from 1998—2003. In field tests, seeds germinated equally well in soils from occupied and unoccupied habitats. Seeds persisted in the seed bank and germinated (< 1%/year) for 3 years following sowing. Seedling survival was greatest in currently occupied habitat and dropped to zero in some habitats with the onset of severe drought. Shrubs conferred protection to wild seedlings, but decreased caged seedling survival. For 4 years following germination, caged seedlings had greater survival than natural seedling cohorts. Among 16 factors measured, soil moisture significantly explained between 62 and 71% of the variation in recruitment in both wild and caged plots. Expansion of P. subintegra into novel habitats is limited by soil moisture capacity, but reintroductions to limestone mesas are possible and most promising if cages and supplemental watering are used.

Center for Plant Conservation
  • 11/25/2021
  • Reintroduction

Cuttings of Purshia subintegra were taken April 2001 from a Verde Valley population that was slated to be demolished during construction of a new road. These cuttings were rooted in the greenhouse, and planted in 1 gallon pots with a native soil/potting soil mix. In April 2003, 410 individuals were planted on two separate introduction sites of suitable habitat, one site in State Park land and another on conservation land. This allowed for greater protection from human disturbance. Individuals were planted in a variety of soil habitats, ranging from sandy to rocky bedrock soil, and ranging in color from the typical white limestone, to a light red sandstone. Supplimental water was provided to each plant, at a rate of 2 gallons per individual per watering session. For five months they were watered twice per week, then reduced for one month at once per week, then reduced again to once every two weeks for 7 months. Water was given for a total of 18 months. Overall, success for the first year was around 79%. There was not much variation between the two sites. Total success for the first three years was 41%. The microsite that had the best success was the rockiest and whitest, with 56% success for three years. The microsites that performed the worst were the red sandy soils and the red rocky soils with 26% success for three years. This goes along with the theory that Purshia subintegra prefers white limestone bedrock soils.

Center for Plant Conservation
  • 11/25/2021
  • Reintroduction

Purshia subintegra is a rare soil endemic from the northern ecotone of the Sonoran Desert, in the Verde Valley of Arizona. The main goal of this experiment was to reintroduce plants to the wild. While doing this, the Arboretum at Flagstaff examined the methods that would optimize transplanting success with 2 separate reintroduction trials. In the first trial, we were interested in the amount of care necessary to ensure survival of the plants. Therefore, we examined the effect of irrigating with additional water on transplant success. In the second trial, we examined the season of planting as well as microsite variation. Comparing the two trials, we were able to examine the effects of propagating individuals with native soil or purchased soil, and the effect this had on transplanting success.

Results showed that adding water for the first 6 months of transplanting greatly increased survivorship. Planting in February was more successful than planting in November. Also, growing the plants initially in native soil helped their transplanting success. For plants planted in February, survival did not vary significantly between microsites.

Sheila Murray
  • 10/11/2021
  • Seed Collection

CPC received a grant from the Institute for Museum and Library Services (IMLS) for a project entitled, “RNA integrity as a powerful metric of aging in preserved seed collections of wild rare plant species”, and as part of this grant The Arboretum at Flagstaff collected seeds for Purshia subintegra, or the Arizona Cliffrose. We collected 800 seeds bulked together in July of 2021. These fresh seeds will be compared to older seed we collected from the same population to find out how fast rare seeds are losing their viability in storage. The seed collecting conditions in 2021 were vastly superior to conditions in 2020, in which Northern Arizona experienced the worst drought in recorded history. Plants all across the ecosystem responded well to the shift back to a relatively normal amount of rainfall.

Center for Plant Conservation
  • 08/19/2021
  • Orthodox Seed Banking

In 2021, CPC contracted the Arboretum at Flagstaff to recollect seed from a population currently held in long term orthodox seed storage as part of an IMLS-funded seed longevity experiment. The National Laboratory for Genetic Resources Preservation will evaluate how germination tested viability and RNA Integrity of seed lots decline over time in storage.

  • 10/17/2020
  • Propagation Research

Our ongoing studies of Arizona cliffrose, Purshia subintegra, have concentrated on many aspects of understanding the biology of the species. Arizona cliffrose is known from 4 disjunct populations in central Arizona. The largest and healthiest population is found on state land in the Verde Valley, where new road construction will bisect the population, destroy approximately 10% of the plants in the population, and destroy available and potential habitat. This plant has extremely deep tap roots, making direct transplantation of threatened individuals to a new location away from the road construction is not possible. Therefore, in order to preserve these plants (with their potentially unique genes) it is necessary to cultivate them either from seeds or cuttings. Until a few yeas ago, this was not possible, as a drought kept the threatened individuals from producing seed, and cultivation from cuttings was considered difficult if not impossible to accomplish. From 1996-2000, the Arboretum at Flagstaff undertook a mitigation project that entailed learning how to cultivate Arizona cliffrose from cuttings of 65 plants that were threatened by the construction of one road. After a year of work, protocols were finally established for the successful cultivation of this species from cuttings. While not fast, (can take from 6 months to 1 year) this knowledge was key to saving the individuals in the population that were slated to be destroyed by the planned road. The next step of the process was determining the methods to successfully reintroduce this desert plant into its native habitat. To do this, The Arboretum at Flagstaff conducted 4 experimental reintroduction trials, and found that growing the cuttings in native soil, transplanting them to the reintroduction in February, and watering them for over 5 months resulted in the greatest survival. As of 2002, the results were somewhat promising, as some of the individuals in the reintroduced population were able to survive a second year of drought--the worst in recorded history in the area. (Maschinski 2000)

  • 10/17/2020
  • Reintroduction

Our ongoing studies of Arizona cliffrose, Purshia subintegra, have concentrated on many aspects of understanding the biology of the species. Arizona cliffrose is known from 4 disjunct populations in central Arizona. The largest and healthiest population is found on state land in the Verde Valley, where new road construction will bisect the population, destroy approximately 10% of the plants in the population, and destroy available and potential habitat. This plant has extremely deep tap roots, making direct transplantation of threatened individuals to a new location away from the road construction is not possible. Therefore, in order to preserve these plants (with their potentially unique genes) it is necessary to cultivate them either from seeds or cuttings. Until a few yeas ago, this was not possible, as a drought kept the threatened individuals from producing seed, and cultivation from cuttings was considered difficult if not impossible to accomplish. From 1996-2000, the Arboretum at Flagstaff undertook a mitigation project that entailed learning how to cultivate Arizona cliffrose from cuttings of 65 plants that were threatened by the construction of one road. After a year of work, protocols were finally established for the successful cultivation of this species from cuttings. While not fast, (can take from 6 months to 1 year) this knowledge was key to saving the individuals in the population that were slated to be destroyed by the planned road. The next step of the process was determining the methods to successfully reintroduce this desert plant into its native habitat. To do this, The Arboretum at Flagstaff conducted 4 experimental reintroduction trials, and found that growing the cuttings in native soil, transplanting them to the reintroduction in February, and watering them for over 5 months resulted in the greatest survival. As of 2002, the results were somewhat promising, as some of the individuals in the reintroduced population were able to survive a second year of drought--the worst in recorded history in the area. (Maschinski 2000)

  • 10/17/2020
  • Demographic Research

The acquisition of long-term datasets can represent decades of really hard work and thousands of dollars in exhausted resources. The standard model of monitoring these sites year after year is unsustainable for most organizations especially small organizations such as the Arboretum at Flagstaff. FLAG set out to address three different questions using a demography dataset of Purshia subintegra (Arizona cliffrose) spanning 22 years: (1) What is the long-term viability of the population? (2) What are the specific life stages that are potentially impeding population growth? (3) Is it possible to make modifications to the monitoring protocol to become more efficient and minimize resource use? This 22-year dataset of Purshia subintegra is based on the following criteria: (1) 3 plot types (random, high density, hybrid). (2) 10 m transects (40 m2 plot area); n=61 total plots. (3) Metrics: size, phenology, #flowers, #seeds, seedling count, damage, and mapping of new individuals. (4) 2 people x 5 days = 10 days of labor, plus travel (~100 mi RT x 5) to monitor all plots. Prior to making any procedure changes the question of the long-term viability of the population must be addressed. Therefore, based on the 100-Year Stochastic Projection for 24 Random Plots with results of 5000 Iterations and an initial population of 233 individuals - the probability of extinction or a significant high decrease of individuals is very high. Subsequently, the need to monitor still exists. Also based on the 21 years of demography data, it was noted that the number of reproductive mature adults was quite stable over time but the seedling recruitment into the next juvenile stage was abysmal. The next pertinent question was if there exists important correlations with different weather events. Further study of the Verde Valley which has a mean annual precipitation of 11.7 inches revealed that if the annual precipitation was the mean or less, the mean number of seedlings was less than 1 per plot. In years with even slightly more than the mean annual precipitation the number of seedlings jumped to 1 or greater per plot. This finding represents the crucial period for monitoring because these individuals represent recruitment into the next stage. (Haskins et al. 2018)

Elvia Ryan
  • 07/31/2018

Based on findings of a long term population monitoring, low annual precipitation affects seedling recruitment into the next stage. (Haskins et al. 2018)

Elvia Ryan
  • 07/27/2018

Based on findings, Arboretum at Flagstaff will implement the following:  (1) Reduce the number of plots to monitor, focusing on the 24 random plots.  (2) Track annual precipitation and monitor in years that expect seedling booms AND years in which high mortality is expected.  (3) These changes will capture important life history events and minimize labor and resource costs.  (Haskins et al. 2018)

Elvia Ryan
  • 07/27/2018

The acquisition of long-term datasets can represent decades of really hard work and thousands of dollars in exhausted resources.  The standard model of monitoring these sites year after year is unsustainable for most organizations especially small organizations such as the Arboretum at Flagstaff.   FLAG set out to address three different questions using a demography dataset of Purshia subintegra (Arizona cliffrose) spanning 22 years: 
(1) What is the long-term viability of the population?  (2) What are the specific life stages that are potentially impeding population growth?  (3) Is it possible to make modifications to the monitoring protocol to become more efficient and minimize resource use?  This 22-year dataset of Purshia subintegra is based on the following criteria:  (1) 3 plot types (random, high density, hybrid).  (2) 10 m transects (40 m2 plot area); n=61 total plots.  (3) Metrics: size, phenology, #flowers, #seeds, seedling count, damage, and mapping of new individuals.  (4) 2 people x 5 days = 10 days of labor, plus travel (~100 mi RT x 5) to monitor all plots.  Prior to making any procedure changes the question of the long-term viability of the population must be addressed.  Therefore, based on the 100-Year Stochastic Projection for 24 Random Plots with results of 5000 Iterations and an initial population of 233 individuals - the probability of extinction or a significant high decrease of individuals is very high.  Subsequently, the need to monitor still exists.  Also based on the 21 years of demography data, it was noted that the number of reproductive mature adults was quite stable over time but the seedling recruitment into the next juvenile stage was abysmal.  The next pertinent question was if there exists important correlations with different weather events.  Further study of the Verde Valley which has a mean annual precipitation of 11.7 inches revealed that if the annual precipitation was the mean or less, the mean number of seedlings was less than 1 per plot.  In years with even slightly more than the mean annual precipitation the number of seedlings jumped to 1 or greater per plot.  This finding represents the crucial period for monitoring because these individuals represent recruitment into the next stage.  (Haskins et al. 2018)

Nature Serve Biotics
  • 05/02/2017

Narrowly restricted to infertile, white, calcareous deposits in central Arizona. Five populations are known and each is threatened to varying degrees by cattle and burro grazing, mineral exploration and development, urbanization, road construction, off-road vehicle traffic, and pesticide use.

Joyce Maschinski, Ph.D.
  • 01/01/2010

Threats include: urbanization mining overuse by cattle and burros road construction off-road vehicle traffic extended drought (USFWS 1995)

Joyce Maschinski, Ph.D.
  • 01/01/2010

This species is found in four localities in central Arizona below the Mogollon Rim. The most northern of these four locations contains the healthiest individuals, but these are threatened by road construction.

Joyce Maschinski, Ph.D.
  • 01/01/2010

Our ongoing studies of Arizona cliffrose, Purshia subintegra, have concentrated on many aspects of understanding the biology of the species. Arizona cliffrose is known from 4 disjunct populations in central Arizona. The largest and healthiest population is found on state land in the Verde Valley, where new road construction will bisect the population, destroy approximately 10% of the plants in the population, and destroy available and potential habitat. This plant has extremely deep tap roots, making direct transplantation of threatened individuals to a new location away from the road construction is not possible. Therefore, in order to preserve these plants (with their potentially unique genes) it is necessary to cultivate them either from seeds or cuttings. Until a few yeas ago, this was not possible, as a drought kept the threatened individuals from producing seed, and cultivation from cuttings was considered difficult if not impossible to accomplish. From 1996-2000, the Arboretum at Flagstaff undertook a mitigation project that entailed learning how to cultivate Arizona cliffrose from cuttings of 65 plants that were threatened by the construction of one road. After a year of work, protocols were finally established for the successful cultivation of this species from cuttings. While not fast, (can take from 6 months to 1 year) this knowledge was key to saving the individuals in the population that were slated to be destroyed by the planned road. The next step of the process was determining the methods to successfully reintroduce this desert plant into its native habitat. To do this, The Arboretum at Flagstaff conducted 4 experimental reintroduction trials, and found that growing the cuttings in native soil, transplanting them to the reintroduction in February, and watering them for over 5 months resulted in the greatest survival. As of 2002, the results were somewhat promising, as some of the individuals in the reintroduced population were able to survive a second year of drought--the worst in recorded history in the area. (Maschinski 2000)

Joyce Maschinski, Ph.D.
  • 01/01/2010

A management plan is being developed for the USFS lands holding Purshia subintegra in the Verde Valley. There is a good chance that more Purshia habitat will be protected.

Joyce Maschinski, Ph.D.
  • 01/01/2010

Research needs include continued genetic and demographic studies.

Joyce Maschinski, Ph.D.
  • 01/01/2010

The Arboretum at Flagstaff will continue to collect the genotypes of individuals that will be destroyed from road work and use knowledge of cultivation protocols to eventually reintroduce these individuals to the newly protected habitat on federal land.

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Nomenclature
Taxon Purshia subintegra
Authority (Kearney) Henrickson
Family Rosaceae
CPC Number 1097
ITIS 195903
USDA PUSU2
Common Names Arizona cliffrose | Arizona cliff-rose | subintegra bitterbrush
Associated Scientific Names Purshia subintegra | Cowania subintegra | Purshia pinkavae
Distribution It is known from 4 disjunct populations across central Arizona in the upper Sonoran desert on Tertiary lakebed limestone deposits: Burro Creek in Mohave County (Kearney 1943), Bylas, Graham County (Pi
State Rank
State State Rank
Arizona S2
Habitat

Plants seem to be restricted to a single layer of chalky white lake deposit limestone, which form the top layer of finger-like mesas. (USFWS 1995)

Ecological Relationships

The largest population of Arizona cliffrose grows in the Verde Valley of Arizona, where it comes into contact with common cliffrose and forms introgressed forms. Hybridization is an issue for this species. The species germinates after a period of cold stratification and seeds have a fairly high viability. However, the species is difficult to maintain in cultivation. It has extremely large and deep taproots in the wild.The drought of 2001 and 2002 in this species habitat is a huge threat to its continued survival. A population viability analysis has shown that the species is undergoing a slow but steady decline in both in natural and reintroduced populations.(Maschinski 2000; USFWS 1995)

Pollinators
Common Name Name in Text Association Type Source InteractionID
Bees
Anthophorine bees Anthophoridae Confirmed Pollinator Link
Honey bees Apis mellifera Confirmed Pollinator Link
Masked bees Collectidae Confirmed Pollinator Link
Sweat bees Dialictus Confirmed Pollinator Link
Sweat bees Halictidae Confirmed Pollinator Link
Flies
Syrphid flies Syrphid flies Confirmed Pollinator Link

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