Ocotillo Research Articles

TWO DISTINCT GROWTH FORMS OF THE ICONIC DESERT SHRUB OCOTILLO (FOUQUIERIA SPLENDENS): TARANTULA AND V-FORM

The discovery of an atypically shaped Ocotillo (Fouquieria splendens Englem.) at one of my research sites in the foothills of the Organ Mountains in southern New Mexico led to a study to determine whether this was an oddity or a recurring growth form. Ocotillo, the iconic C3, drought-deciduous desert shrub of the Chihuahuan and Sonoran Deserts, typically appears as a multistemmed, spine-laden shrub described as having the appearance of an inverted cone. The new growth form introduced here departed markedly from the V-shape so often associated with Ocotillo. The new growth form, termed Tarantula because its stems are reminiscent of the low, arching legs of the spider, is characterized by having a) a ratio of <0.8 between the maximum height above ground of its longest stem and the maximum length of the same stem, b) an angle between the longest stem and the ground of <50°, and c) stems with a horizontal or downward arching curvature. In 71 transects distributed across four states in the United States and two states in Mexico, 8% of the 6739 Ocotillos sampled were the Tarantula growth form. The mean percentage of Tarantula plants per transect was 8.9%. Six hypotheses are offered as potential explanations for the atypical architecture of the Tarantula growth form. That none of these hypotheses provided a definitive explanation indicates that this visually distinct, widely distributed variant of Fouquieria splendens merits further study. Three avenues of future research are suggested.

Reproduction and vegetative growth do not follow reciprocity theory in the C3 desert shrub ocotillo (Fouquieria splendens)

Theory predicts the existence of a negative, reciprocal relationship between reproduction and vegetative growth. However, research and supporting data have focused on small, herbaceous plants growing in temperate environments. To test the underlying theory in a completely different environment, nine years of stem-specific data for a large, stem-succulent desert shrub explored the relationship between fruit production and growth. Measures of reproduction (annual presence/absence of infructescences and numbers of fruit capsules) and vegetative growth (annual increment of stem elongation) were measured in stems of two populations of ocotillo (Fouquieria splendens) growing in the Chihuahuan Desert in 2007–2015. Stem growth was significantly less in stems that produced infructescences than in stems lacking infructescences. The number of fruit capsules produced was also inversely related to stem growth. The reverse was not true. Stem growth prior to infructescence production did not have a significant impact on reproduction. The tenet that growth and reproduction are negative, reciprocal processes did not hold in ocotillo: reproduction negatively impacted vegetative growth, but growth did not impact reproduction. This atypical relationship in allocation to reproductive and vegetative tissues in this perennial desert shrub adds to the diversity of patterns known for optimal plant resource allocation.

Chemical composition and toxicity of extracts of &lt;i&gt;Fouquieria splendens&lt;/i&gt; against &lt;i&gt;Artemia salina&lt;/i&gt;

&lt;abstract&gt; &lt;p&gt;Ocotillo (&lt;italic&gt;Fouquieria splendens&lt;/italic&gt;) has been used in Mexican traditional medicine for the treatment of blood circulation problems, swelling, and prostatic hyperplasia, among others. The objective of this study was to use different extraction methods (soxhlet, hydrodistillation and ultrasound) and solvents with different polarities (hexane, methyl chloride, ethyl acetate, acetone and methanol) to determine volatile compounds contained in ocotillo stems. Solvents used were water in hydrodistillation; hexane, methyl chloride, ethyl acetate, acetone, and methanol in soxhlet; and a solvent mixture of water acidified with methanol, acetone, and 1% acetic acid at a 50:35:15 ratio in the ultrasound method. The major components identified were bis (2-Ethylhexyl) phthalate, bis (2-Ethylhexyl) ester, butyl acetate, palmitic acid, and myristic acid. A toxicity assay on &lt;italic&gt;Artemia salina&lt;/italic&gt; was conducted and the median lethal concentration was quantified. The bioassay showed that extracts isolated by non-polar solvents are extremely toxic because they were lethal at concentrations lower than 100 ppm, while polar extracts were innocuous. However, in polar extracts were found compounds that suggest their use in traditional medicine, the most relevant being 2-butoxyethanol, pentadecanol, and undecanal.&lt;/p&gt; &lt;/abstract&gt;

Fouquieria splendens: A source of phenolic compounds with antioxidant and antiproliferative potential

Fouquieria splendens commonly named "ocotillo", is a native plant from Mexico, used in folk medicine against different illnesses. However, scientific evidence about its biological activities is limited. The objective of this study was to determine phenolic composition, antioxidant and antiproliferative effect of F. splendens . Amethanolic extract from F. splendens leaves extract ( F. splendens extract) was obtained and fractioned by liquid-liquid partition, obtaining hexane, ethyl acetate, and residual fractions. Phenolic compounds were determined by the Folin Ciocalteu method, and the phenolic profile was assessed by UPLC-DAD. Antioxidant activity was determined by DPPH, TEAC, ORAC, and FRAP assays. Antiproliferative activity was performed by MTT assay against C33-A and HeLa cell lines. The ethyl acetate fraction exhibited the highest ( p < 0.0001) amount of phenolic compounds (479.9 mg GAE/g) and the predominant compounds were gallic acid ( 25.949 mg/g), ellagic acid ( 17.439 mg/g), and kaempferol-3-β-glucoside ( 7.336 mg/g). Similarly, ethyl acetate fraction exhibited the highest ( p < 0.0001) antioxidant potential (DPPH: 2430.1 µmol TE/g; TEAC: 60.4 µmol TE/g; ORAC: 4948.4 µmol TE/g; FRAP: 7803 µmol Fe(II)/g). An antiproliferative assay evidenced that the F. splendens extract was the most effective ( p < 0.0002) to inhibit proliferation of cervical cancer cell lines, particularly HPV negative cells (C33-A IC 50 : 9.06 µg/mL; HeLa IC 50 : 74.7 µg/mL). The results showed a promissory biological potential of F. splendens , associated with phenolic compounds, besides the first report on the identification of some phenolic compounds in this plant.

Isolation of ocotillol/ocotillone from Fouquieria splendens (Ocote) using a batch reactor

Exploitation of the "ocotillo" tree (Fouquieria splendens Engelm) to produce ocotillol/ocotillone (o/o) in Northern Mexico hasn’t been explored to this date. In the present work, isolation of ocotillol/ocotillone was performed through a batch reactor, which allowed the elimination of alcohol and phenols present in the ocote plant, yielding only resins and waxes from the ocote trunks. The ocotillol/ocotillone was extracted from the remaining resin on the ocote logs by solvent extraction in a batch reactor, to be crystallized after its extraction using a rotary evaporator. FTIR, and NMR analysis exhibited the characteristic ginsenoside bands, while the UV-vis spectrum of ocotillol/ocotillone depicted an absorption band belonging to the O–H bonds, indicating that the group is anchored to the ginsenoside structure and not due to a water signal. Lastly, the thermogravimetric analysis described a common behavior among other ginsenosides. Production of ocotillo/ocotillone has an energy consumption of 3624 kWh/gr. With a cost of $0.478 USD in laboratory equipment, which translates as a plausible sustainable production of ocotillol/ocotillone

Long-term survival and flowering of ocotillo (Fouquieria splendens) in Texas: A 33-year perspective

Perennial plants of desert regions can be categorized as short-, moderate-, or long-lived. For long-lived species, the typical range of adult life spans is often poorly known, as well as how reproductive effort is apportioned across years. Ocotillo (Fouquieria splendens), a large shrub of the Chihuahuan and Sonoran Deserts, is considered long-lived and flowers spectacularly, but few data exist on these aspects of its life history. In Big Bend National Park, Texas, I marked 140 mature ocotillos in 1986–1988 at 8 sites and measured inflorescence production. In 1990, 2003, 2018, and 2019, I again measured flower output and determined fates of 95 plants which could be relocated, 64% of which survived the 33-year interval. Smaller plants survived better than larger ones. With an annual survival probability of 0.986, the median plant entering adulthood was projected to live 51 more years. All plants flowered in each study year unless buds froze; means ranged from 8 to 60 inflorescences (approximately 680–5200 flowers) per plant per site. Most survivors made more inflorescences in 2018–19 than 29–33 years earlier. Thus, an average ocotillo produces large crops of flowers for approximately 50 years, an appropriate strategy if seedlings rarely survive.

Activity patterns and their relationship to the habitat use of mule deer (Odocoileus hemionus) in the Chihuahuan Desert, Mexico

In desert regions, species have adapted physiologically and behaviorally to the extreme conditions of their environment, such as a lack of water and extreme temperatures. This is the case of the mule deer (Odocoileus hemionus) a species which many aspects of its relationship between behavioral ecology and habitat characteristics are unknown. The objectives of this study were: 1) to characterize the daily activity pattern of female mule deer in relationship to three behavioral patterns: resting, feeding and moving, and 2) assess the relationship between these behavioral patterns and the characteristics of the habitat. This study was conducted in the Chihuahuan Desert, where six females of mule deer were monitored using VHF radiotelemetry between 2012 and 2014. We distinguish the behavioral patterns by sensors in the collar and we quantified the number of beeps emitted per minute. Moreover, we described the daily pattern associated with these activities using Kernel density graphs and evaluated the effect of habitat variables on the frequency of resting and feeding behaviors applying a generalized linear model (GLM). We identified the location in which feeding and resting behaviors occurred, and the type of plant associations present and the percentage of area they occupied. We recorded locations over 328 days/deer. Female mule deer spent most of their time resting (63.41 %), followed by moving (21.26 %), and feeding (15.34 %). Deer movement and feeding behaviors were most frequent during the crepuscule. The temperature was the only variable that influenced resting and feeding behaviors (deviance = 4.7; d. f. = 1; P = 0.02). The estimated area used for resting was 10.35 km2, while the corresponding area for feeding was 6.45 km2, in which the plant association with dominance of Larrea tridentata, Opuntia rastrera and Fouquieria splendens was the most common. Considering the high temperatures prevailing on the region, resting most of the day likely helps deer to have an adequate thermoregulation. The time dedicated to feeding is less than the dedicated to other activities; deer may be spending more time moving than feeding due to the spatial distribution of suitable food patches, or to avoid predators. The mule deer occupy the same areas to feed and rest; however, feeding areas are smaller those used to rest, these areas have been identified in previous studies as those with the greatest use (core areas). In the plant association with greater occupation within the feeding zones, there are species reported as an essential for the deer diet; these areas are located at the foot of the hill, which gives the deer thermal protection.

Stem succulence controls flower and fruit production but not stem growth in the desert shrub ocotillo (Fouquieria splendens).

The C3 desert shrub ocotillo (Fouquieria splendens) completely lacks xeromorphic leaves but is uncommonly both stem succulent and repetitively drought deciduous (documented to have produced many foliation-defoliation cycles during a growing season). Both adaptations conserve water in this xerophyte, but are the roles of succulence and deciduousness merely redundant? The observation that year-to-year reproductive effort was relatively consistent while vegetative growth was not offered a critical clue that, coupled with long-term precipitation data, helped answer this question. At two sites in the Chihuahuan Desert in southern New Mexico, United States, 22 ocotillos were studied annually for more than two decades to explore the relationships among reproductive effort, vegetative stem growth, and patterns of precipitation. Vegetative stem growth occurred in mid- to late summer (July-September), the season of maximum precipitation in the Chihuahuan Desert, and was significantly related to summer precipitation received in the year of growth. Reproductive effort occurred in early to late spring (April-June), which with winter account for minimum precipitation during the year, but was significantly related to summer precipitation received in the previous year, suggesting the importance of stem succulence and stored water. While highly variable summer precipitation was responsible for enormous fluctuations in annual ocotillo stem growth, stem succulence insulated reproductive effort from such immense variability. Stem-stored water allowed the production of flowers and fruits to proceed relatively consistently during the driest years and during the driest time of year in the Chihuahuan Desert.

Factors affecting the selection of and displacement within core areas by female mule deer (Odocoileus hemionus) in the Chihuahuan Desert, Mexico

Core activity areas are the most important sites within an animal’s home range as they contain the greatest density of critical resources. Because these areas are small and intensively used, they can affect the total distances covered by animals searching for resources. Our objective was to document which habitat variables affect core area selection by female mule deer (Odocoileus hemionus) in an arid environment, and to learn which variables affect their displacement within these areas. Using radiotelemetry, from 2012 to 2014 we monitored seven female mule deer. We estimated their core areas, and with this information we identified and classified the location records as inside or outside of the core area. For each record, we also recorded variables related to time (month, time of day), environmental conditions (temperature, relative humidity), and habitat characteristics (plant association, distance to the nearest water body, slope), and used them to predict the presence of the deer in the core area using Classification and Regression Trees (CART). The same variables were analyzed using a GLM to determine which factors explain variations in displacement distance. The most important variable in core area selection was the distance to the nearest body of water (<933.71m at the population level and <1375.11m on average for individual deer), followed by two plant associations that included the dominant species Prosopis glandulosa, Pleuraphis mutica, Larrea tridentata, Opuntia rastrera and Fouquieria splendens in areas with a gentle slope or none. Displacement distances within the core area were shorter than those outside and were affected by time of day and month. Our results are the first to elucidate the use of the core area by female mule deer in the Chihuahuan Desert, and allow us to start understanding the connection between the habitat resources essential to the survival of these deer and their movement under desert conditions.

Ocotillo flowers as food resource for the mule deer during the dry season

The plant locally known as ocotillo, Fouquieria splendens (Fouquieriaceae) is a shrub distributed in arid zones of Mexico and southwestern United States. In Mapimi Biosphere Reserve, Durango, it has not leaves for most of the year; these emerge after the first rain. Inflorescences emerge in March, being bright red and lasting only a month. These inflorescences are highly sought after by animals, including insects, birds and the mule deer (Odocoileus hemionus). The objectives of this study were: 1) quantify the inflorescences produced by each plant (during March), 2) estimate inflorescence availability for mule deer, and 3) quantify its contribution in biomass (fresh weight) and nutrient content. This will contribute to understand why deer consume these flowers in the dry season. In March 2012 a field sampling was carried out in the Mapimi Biosphere Reserve, to measure the characteristics of each individual plant, quantify the number of inflorescences produced, the number available for mule deer, and the nutrients they contribute. The nearest-neighbor method was used, measuring 30 ocotillo individuals in nine sites. Inflorescences were collected from different plants to estimate fresh weight and determine nutrient content by proximal chemical analysis. A total of 270 ocotillo plants were sampled. There was a positive correlation between plant diameter and number of both branches and inflorescences. An average of 30 inflorescences was observed, and their availability for deer was 42 % (3,306/7,951) of the total. The average weight of 74 inflorescences collected was 74.8 ± 20.4 g; each plant produced up to 3 kg. These contain high levels of protein (15 % dry basis), carbohydrate (67 %), and 3,085.98 kcal/kg of metabolizable energy; 85 % are digestible nutrients. The mule deer selects plants with high nutritional values that are available in critical seasons such as the dry season. To note, ocotillo flowers emerge when there is food shortage (dry season), and are consumed by deer. A positive correlation was found between number of branches, plant diameter and total number of inflorescences (and its availability). Ocotillo flowers represent an important nutritional resource for deer, because inflorescences have high protein and sugar levels, in addition to having digestible nutrients and that each plant produces around 1.5 kg of inflorescences available for deer in the dry season.

Are growth rings accurate fingerprints of plant age in a stem-succulent, drought-deciduous shrub growing in the Chihuahuan Desert?

Ocotillo (Fouquieria splendens), an iconic plant of the Chihuahuan and Sonoran Deserts in the United States and Mexico, has the reputation of being a long-lived shrub capable of attaining ages of two centuries or more. However, evidence of this potential longevity is lacking given that 104 years has been the oldest confirmed age recorded. The recent finding that growth rings can be accurately counted in the woody trunks of ocotillo has provided an opportunity to determine whether these rings merely identify the punctuated, sporadic growth common in this plant, or whether they actually represent ocotillo age. In seedlings studied for 22 years in southern New Mexico, growth rings enumerated in their trunks equaled total plant age. This apparent equivalence between growth rings and age was in spite of the fact that no measurable stem elongation occurred in up to nine of the 22 years of study in an ocotillo that also had no stem elongation in four consecutive years. A mature ocotillo harvested at this site that had 107 growth rings further supports the reality of a century-plus lifespan for ocotillo. The puzzle of longevity in this distinctive shrub of the desert Southwest can now be addressed with future research, but the possibilities go beyond the determination of maximum lifespan. These possibilities include dendrochronological studies that may well allow important analyses of patterns related to climate change in deserts where biological monitors of change are not always present or obvious.

Tracking growth and age in the drought-deciduous shrubFouquieria splendens(ocotillo) in the Chihuahuan Desert: The role of wood rings and stem segments

Abstract I studied growth and longevity of the C3 drought-deciduous shrub Fouquieria splendens (ocotillo) growing in the Chihuahuan Desert in New Mexico for 22 years through the analysis of rings produced in trunks and stems. Ocotillos studied had 1–64 stems longer than 40 cm, maximum stem lengths of 50–370 cm, and 21–107 growth rings in their trunks. Although trunk rings were positively related to stem rings immediately above the trunks, the base of the largest stems immediately above the trunks had up to 58% fewer rings than the trunks. One growth ring was added to every existing stem segment only in years when a new terminal segment was produced on that stem, and adjacent segments produced in the same year had only one growth ring each. While the 107 growth rings in the trunk of the presumably oldest ocotillo in this study closely match the oldest ocotillo age derived from direct evidence (104 years), the challenge now is to discover whether ocotillo trunk rings really are annual rings.

Forecasting climate change impacts to plant community composition in the Sonoran Desert region

AbstractHotter and drier conditions projected for the southwestern United States can have a large impact on the abundance and composition of long‐lived desert plant species. We used long‐term vegetation monitoring results from 39 large plots across four protected sites in the Sonoran Desert region to determine how plant species have responded to past climate variability. This cross‐site analysis identified the plant species and functional types susceptible to climate change, the magnitude of their responses, and potential climate thresholds. In the relatively mesic mesquite savanna communities, perennial grasses declined with a decrease in annual precipitation, cacti increased, and there was a reversal of the Prosopis velutina expansion experienced in the 20th century in response to increasing mean annual temperature (MAT). In the more xeric Arizona Upland communities, the dominant leguminous tree, Cercidium microphyllum, declined on hillslopes, and the shrub Fouquieria splendens decreased, especially on south‐ and west‐facing slopes in response to increasing MAT. In the most xeric shrublands, the codominant species Larrea tridentata and its hemiparasite Krameria grayi decreased with a decrease in cool season precipitation and increased aridity, respectively. This regional‐scale assessment of plant species response to recent climate variability is critical for forecasting future shifts in plant community composition, structure, and productivity.

Understanding Interaction Effects of Climate Change and Fire Management on Bird Distributions through Combined Process and Habitat Models

Avian conservation efforts must account for changes in vegetation composition and structure associated with climate change. We modeled vegetation change and the probability of occurrence of birds to project changes in winter bird distributions associated with climate change and fire management in the northern Chihuahuan Desert (southwestern U.S.A.). We simulated vegetation change in a process-based model (Landscape and Fire Simulator) in which anticipated climate change was associated with doubling of current atmospheric carbon dioxide over the next 50 years. We estimated the relative probability of bird occurrence on the basis of statistical models derived from field observations of birds and data on vegetation type, topography, and roads. We selected 3 focal species, Scaled Quail (Callipepla squamata), Loggerhead Shrike (Lanius ludovicianus), and Rock Wren (Salpinctes obsoletus), that had a range of probabilities of occurrence for our study area. Our simulations projected increases in relative probability of bird occurrence in shrubland and decreases in grassland and Yucca spp. and ocotillo (Fouquieria splendens) vegetation. Generally, the relative probability of occurrence of all 3 species was highest in shrubland because leaf-area index values were lower in shrubland. This high probability of occurrence likely is related to the species' use of open vegetation for foraging. Fire suppression had little effect on projected vegetation composition because as climate changed there was less fuel and burned area. Our results show that if future water limits on plant type are considered, models that incorporate spatial data may suggest how and where different species of birds may respond to vegetation changes.

Flowers are Produced on Stems Shorter than One Meter in the Desert Shrub Ocotillo (Fouquieria splendens)

Abstract The minimum length of stem required for production of flowers in the C3 desert shrub ocotillo (Fouquieria splendens) has been widely accepted as 1 m since 1943. Long-term studies in the Chihuahuan Desert indicate that this threshold is no longer acceptable. During 2003–2006, 15 ocotillo stems shorter than 1 m produced 1–32 flowers each. The shortest stem on which flowers were produced was 62 cm long. Although fully capable of producing flowers, the contribution of stems <1 m long to overall production of flowers was small, accounting for only 0.49% of all flower-bearing stems. Stems <1 m long can no longer be excluded from studies of allocation to reproduction in ocotillo because of their assumed inability to produce flowers.

Dry Mass Partitioning and Gas Exchange for Young Ocotillos (Fouquieria splendens) in the Sonoran Desert

A continuum of juvenile to reproductively mature ocotillos (Fouquieria splendens) was studied to determine changes in dry mass partitioning and production in relation to plant morphology. Gas exchange and productivity for 1‐yr‐old plants were also studied under controlled temperatures typical of winter, spring, and summer, which are the seasons that receive rain in the Sonoran Desert. Root:shoot ratios of young ocotillos decreased with total plant dry mass, suggesting smaller plants need relatively more soil resources than do larger plants. Young ocotillos had a greater scaling exponent for plant height versus total plant dry mass than for basal diameter versus total plant dry mass, which is indicative of their shoot morphology. Average rooting depth increased only 0.05 m per meter increase in plant height, reflecting the dependence of ocotillos on shallow soil water and explaining their rapid phenological responses to light rainfall events. Young ocotillos experienced maximal CO2 uptake when exposed to s...

Can zinc influence nutrient resorption? A test with the drought-deciduous desert shrub Fouquieria splendens (ocotillo)

Paradoxically low nitrogen resorption efficiency in the drought-deciduous desert shrub Fouquieria splendens Engelm (ocotillo) triggered tests of the hypotheses that resorption is often low in this species and that resorption is influenced by zinc. Resorption efficiency and proficiency were measured in 1989 and 1994 at two sites in the Chihuahuan Desert in plants to which zinc, or zinc and nitrogen were added. Resorption of nitrogen, phosphorus, and zinc in unfertilized plants varied temporally and spatially, but was both efficient (66%, 49%, and 40%, respectively) and proficient (0.55%, 0.09%, and 9.4 μg g−1, respectively) as determined by comparison to worldwide resorption patterns in a wide variety of other species. Applications of zinc had no significant effect on the resorption of nitrogen and phosphorus, but did influence the resorption of zinc. Resorption of zinc was significantly less efficient in zinc-treated plants than controls at only one of the two sites in one of the 2 years, yet resorption of zinc was significantly less proficient in zinc-treated plants than controls in both years and at both sites. This pattern of zinc resorption adds insight into the continuing debate regarding the relationship between fertility and resorption because the data used to fuel the debate have almost exclusively described macronutrients, not trace metals. The high variability in resorption among individuals, sites, and years observed for F. splendens may well be an attribute of many desert-dwelling, drought-deciduous plants. When senescence is controlled primarily by water availability rather than photoperiod, especially in a landscape characterized by unpredictable amounts and timing of precipitation, high variability in associated processes such as resorption may be inevitable.

LOSS OF LONG-SHOOT LEAVES MAY MASK TERMINAL STEM SEGMENT AGE IN OCOTILLO (FOUQUIERIA SPLENDENS)

Abstract Short-shoot leaves on the terminal stem segments of the drought-deciduous desert shrub ocotillo (Fouquieria splendens) are retained long after long-shoot leaves are lost through senescence and abscission. This formerly unreported observation has relevance for determining whether a terminal stem segment is new or old, because newly produced segments are routinely associated with the presence of long-shoot leaves. It is now clear that the absence of long-shoot leaves on a terminal stem segment cannot be used as unequivocal evidence that the segment is old. The relatively rapid loss of long-shoot leaves from new terminal stem segments may be an adaptation to reduce herbivory by accelerating maturation of the spine that develops from tissues left by each senescing long-shoot petiole.

Biochemical changes and development of leaf tracheary elements of a desert plant Fouquieria splendens ssp. breviflora exposed to water stress

Fouquieria splendens ssp. breviflora is a species of the family Fouquieriaceae, growing in arid zones of México, between 700 and 2100 m above sea level (a.s.l). This species characteristically forms leaf buds under conditions of adequate water supply. The physiological response of this species was studied under varying conditions of irrigation in soil and water, using stems collected during two seasons: dry and rainy; evaluating the foliar material produced the quantity of free proline and total protein and anatomical foliar changes in the water conduction systems. This species displayed distinctive adaptive mechanisms involving the development of foliar fascicles, differentiation of vessels with formation of tracheal elements, and, metabolically, a high proline and total protein content in the stems of the dry season, showing that the responses observed in F. splendens spp. breviflora are adaptive physiological responses that take place simultaneously, being evidence of the first mechanisms of response to water‐stress conditions. Thus, this species is regarded as a poikilohydric plant, as it is capable of the regulation of its metabolism during bud development when flooding events occur in the species' habitat after a prolonged dry and desiccation period.

Decomposition rate of ocotillo (Fouquieria splendens) wood in the desert of southern California and its use in estimating adult survival by life-cycle graph analysis

Dead and downed ocotillos (Fouquieria splendens) are common in the Colorado Desert of southern California and pose a question concerning the life-span of adult plants that have been reported to be long-lived: if ocotillo is long-lived, decay rates must be very slow. Our study focused on decomposition and disintegration of above-ground ocotillo wood over 14 years to obtain a rate of change in dead mass. Disintegration rate was used in a new application of life-cycle graph analysis to calculate persistence time of carcasses, which in turn was used to estimate adult survival rates. We conclude that previous estimates of life spans may be too conservative and half-life of adult shrubs is over 200 years. Our approach to estimating adult survival from decay rates provides an independent test of survival transitions based on live plants for some species and so is an additional tool for developing life cycle models.