Plant Species of the Borrego Desert:
Ferocactus cylindraceus, California barrel cactus Fact Sheet
Ferocactus cylindraceus, California barrel cactus Fact Sheet
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| Fig. 1. Left: Four plants of Ferocactus cylindraceus growing in one of its favorite habitats, a rocky slope. Photo taken by Tom Chester on 6 November 2006 on the Art Smith Trail on the north side of the Santa Rosa Mountains. See also an 18 year repeat photograph of this pix. Right: A beautiful "crown of flowers" from a Ferocactus cylindraceus. Photo taken by Karyn Sauber on 13 March 2022 in the Inner Pasture.
Click on the pictures for a larger version, or to go to the original iNat observation. | |
This page was just begun on 9 January 2025, and so will be incomplete for some time. It began with just a list of the tallest specimens known, but is morphing into a "Fact Sheet" page collecting various bits of info for this species.
Table of Contents
Population Characteristics (Geographic Distribution, Plant sizes, Recruitment, and Nurse Plants)
Plant Characteristics
Lifetime, Mortality, Growth Rate, etc.
Adaptations to Desert Environment by Kate Harper
Tallest Specimens of Ferocactus cylindraceus in the Borrego Desert
Measurements of Height and Width
Introduction
Everyone delights in seeing plants of Ferocactus cylindraceus, California barrel cactus. A landscape filled with barrel cacti of different heights, especially one interspersed with other desert plants, is a beautiful sight! Fig. 1 shows the stark beauty of a landscape with four barrel cacti, and a beautiful plant in full bloom with its "crown of flowers".
This species is fascinating in a number of different ways, detailed in the Plant Characteristics section. Here are four of their amazing characteristics:
- Kate Harper has found that this species has the largest number of characteristics of any of our desert species that enable it to survive in the hostile desert environment.
- Plants of this species apparently almost never die from old age. Instead, they die by falling over, whenever they have grown too long for the angle at which they are growing; from bighorn sheep breaking them open to eat them, and sometimes knocking them over; and possibly from herbivory from small mammals like rabbits. See the section on Mortality below.
- Plants of this species can apparently grow both from winter rain and from summer rain. As a result, the growth rate per year in Arizona is significantly more that of plants in California. As a result, plants of a given height can be significantly older in California. See the section on Growth Rate below.
- This species is an "ant plant". It attracts ants through its extrafloral nectaries, and the ants then defend the buds and developing fruits against predators.
Note on measurement units. Inches and feet are used in the field measurements simply because we happened to have a 12 foot small tape measure that is easy to carry around, as well as other rulers marked in inches, and because most of the time, observers report the height of a plant in feet, by comparison to their height. Because it is difficult to get accurate measurements in the field to less than one inch, measuring heights to the nearest inch is also convenient. If we are undecided about the nearest inch, we will sometimes measure to a half inch. Retaining those units for plots and histograms prevents artificial lumping that might occur after conversion to metric units.
Name Origin
Ferocactus means "fierce cactus"; "cylindraceus" means "cylindrical".
The Baja Spanish common name for a barrel cactus is Bisnaga. ABDSP Rangers named Bisnaga Alta wash for the tall specimen they had found there in 1976. In Spain, bisnaga refers to a "wild carrot", and "bisnaga alta" would mean a "tall wild carrot" (Lindsay 2001, Anza-Borrego A to Z, p. 72).
Population Characteristics
Geographic Distribution. The geographic distribution of F. cylindraceus matches almost perfectly that of the Sonoran Desert Region, with an extension to the north in the Colorado River Drainage Basin into the Mojave Desert, as far north as the latitude of St. George, Utah.
Like many species confined to the Sonoran Desert, F. cylindraceus is limited in its distribution by winter temperatures (Nobel 1980). Seedlings die below 18° F. (-9° C). It also cannot grow at the lowest elevations of the Colorado Desert since there isn't enough rainfall for seedlings to establish (Nobel and Hartsock 1986).
Fig. 2 shows the geographic distribution from two different sources, GBIF and iNat. iNat contains crowd-sourced observations. GBIF includes "research grade" iNat observations and vouchers. Both sources have a number of locations that are erroneous, from various causes, so one should be skeptical of isolated points outside of the main distributions. Click on either map to go to an interactive map of the distribution that can be panned and zoomed.
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| Fig. 2. The geographic distribution of F. cylindraceus from GBIF (left; 19,880 records) and iNat (right; 27,689), as of 14 March 2025. Click on either map to go to an interactive map of the distribution that can be panned and zoomed. | |
Plant sizes. We have measured a total of 131 live specimens, in five separate unbiased surveys of all the barrels in a given area. By "unbiased", we mean the locations were not selected to include previously-known tall specimens, and that we measured every live specimen seen in an area until we had measured at least ~20 plants. The only exception was that if a plant was in a location hard to measure, such as surrounded by Agave plants, we skipped it.
In those surveys, the plant heights range from 2.5 to 67 inches (6.4 to 170 cm), with a median size of 20 inches (51 cm). Summary data for each survey is given in Table 1, and the histogram of those heights is shown in Fig. 3.
Table 1 Summary data of Plant Heights from Each Survey
Sorted by Median Height
| Date | # Measured | Height (inches) | Location | ||
|---|---|---|---|---|---|
| Min | Median | Max | |||
| 1/24/25 | 23 | 2.5 | 14 | 53 | Canyon 41 near S2 |
| 2/8/25 | 40 | 3.5 | 14 | 64 | southern San Felipe Hills |
| 1/11/25 | 22 | 6 | 22 | 55 | near Lower Smuggler 1 |
| 1/31/25 | 29 | 3.5 | 25 | 60 | near Lower Smuggler 2 |
| 1/6/25 | 17 | 11 | 27 | 67 | Rainbow Wash |
| All | 131 | 2.5 | 20 | 67 | All |
Fig. 3. Histogram of heights of 131 measured specimens in five systematic surveys, divided into two groups.
There is a striking difference in the results! Canyon 41 and the southern San Felipe Hills have many more shorter, and presumably younger, barrels than the other three areas. Both the Canyon 41 results and the southern San Felipe Hills were ironic, for the following reasons. The Canyon 41 location was chosen since that area had a preponderance of the tall, older specimens given in Table 2! For the southern San Felipe Hills, we were a bit worred we were biasing the results toward tall specimens in the choice of area to measure there. But in both cases, we kept finding a plethora of young specimens.
The histogram for Canyon 41 + s. San Felipe Hills is strongly peaked at heights of 6 to 14 inches, whereas the histogram for the other three areas peaks at heights of 18 to 30 inches. This implies that there was fairly recent recruitment of barrel cactus in Canyon 41 + s. San Felipe Hills, but not in the other three areas.
Measurements of the growth rate of young barrels vary considerably, from 0.3 to 0.78 inches per year; see the growth rate section below. Using those growth rates, a barrel of height 6 inches now would have germinated from seed 8 to 20 years ago, and a barrel of height 14 inches would have germinated from seed 18 to 47 years ago. More work on the past growth rate is needed before this can be tied to germination years.
It is likely that most of the decline in the histogram above a plant height of 30 inches or so is due to specimens falling over and dying. The tallest specimens known here have all died from falling over within one to six years after discovery; see Table 2. Many of the shorter specimens we see are growing at significant angles from vertical, which inevitably leads to them falling over due simply to gravity as they elongate. One reference (TBS) said that such plants almost always fall over after they hydrate from the first significant rains in the year at which they reach the point where they can't withstand gravity.
The tallest plant found in the unbiased surveys was 67 inches (5.6 feet, 1.7 m) tall. Taller plants exist, but are so infrequent none have shown up in our unbiased surveys. The tallest plant known in the Borrego Desert was 10.33 feet, 3.15 m tall (see Table 2), which is just a bit taller than the 9.8 feet, 3.00 m maximum size for this species given in the Flora of North America treatment.
Recruitment. As is the case for many desert shrubs, recruitment of young plants of F. cylindraceus to join an existing population happens only in wetter than average periods. Seedlings of F. cylindraceus need a longer than average growing period in their first year in order to survive the next drought period. Jordan and Nobel 1981 (Ecology, 62:901) found that in Deep Canyon, on the northern slope of Santa Rosa Mountain, only eight of the 18 years (44%) prior to 1980 had such conditions, with 1976 the last year in that period that allowed recruitment.
The recruitment rate depends also on site. Jordan and Nobel 1982 (Bot. Gaz. 143:511) calculated that in ten sites spread across southern California that had good weather records for 22 to 30 years, suitable years for recruitment varied from 3% to 94%, including 17% at Agave Hill just above Deep Canyon, and 43% in Deep Canyon itself.
Episodic recruitment leads to peaks and valleys in the histogram of plant heights at a given location.
Nurse plants. Desert plants often establish better if seedlings germinate under the shade of another plant, which is then called a "nurse plant". Nurse plants for F. cylindraceus include Ambrosia dumosa, Ephedra aspera, and Hilaria rigida (Nobel 2002, Cacti: Biology and Uses, p. 95.)
Plant Characteristics
Lifetime: The average lifetime of a barrel cactus is much less than the maximum lifetime a plant might achieve. F. cylindraceus plants apparently almost never die from old age; most plants die from falling over, or breaking near the base, whenever they have grown too long for the angle at which they are growing.
Sometimes, the main stem of a plant might fall over, but branches (new stems at the base of a plant), might survive, and even repeat that process. The maximum lifetime in such cases might be much longer than a typical lifetime of a single-stemmed plant.
The typical maximum lifetime is said to be ~55 years in Arizona. The typical maximum lifetime is unknown in California, but possibly at least twice as long here.
The growth rate, and therefore lifetime, might be slower in California than in Arizona, since Arizona has two roughly equal rain periods per year, winter/spring and summer/fall, whereas California typically just has winter/spring rain. If the growth rate in California is half that in Arizona, the plants would take twice as long to get to the size where they fall over, making their lifetime close to twice as long. See the section on Growth Rate below.
The lifetime quoted for Arizona is apparently based on plants shorter than ~1.3 m (~4.3 feet). A 4.3 foot plant in California might be 80 years old.
Ten foot tall plants have been documented Anza Borrego Desert State Park and also in Baja California, which might be 170 years old; see the section on Growth Rate below. We'd be surprised if there weren't 10 foot tall plants in Arizona as well, which would make the maximum lifetime in Arizona be ~80 years from extrapolating the Bowers data.
More details on the Arizona lifetimes:
- Bowers, Webb and Rondeua 1995 (J. Veg. Sci. 6:551), using 355 pairs of repeat photographs at the Grand Canyon dating from 1872, found a maximum longevity of about 55 years. They also wrote: "Height - growth relationship measured over a two year period [in the Grand Canyon] indicate that a plant 90 cm tall is ca. 36 years old, and that a plant 120 cm tall (close to the maximum height) is ca. 45 yr old" (Bowers unpubl. data").
- Separately, Bowers found a maximum age of 49 years in a study of three populations in the Grand Canyon (Bowers 1997 Plant Ecology 133:37).
- The lifetime of its sister species, Ferocactus wislizeni, has been measured in Arizona, and it, too, has a maximum lifetime of ~50 years (Bowers 1997).
Mortality. F. cylindraceus plants apparently almost never die from old age. Instead, they die by falling over, or breaking near the base, whenever they have grown too long for the angle at which they are growing; from bighorn sheep breaking them open to eat them, and sometimes knocking them over; and possibly from herbivory by small mammals such as rabbits.
The inside of a barrel cactus is made of spongy tissue that stores water. There is no woody tissue that might help support the stem.
There are many fairly young plants that are dead because they had the misfortune to start growing at a significant angle from being vertical. This is generally caused because they were just trying to grow away from a plant which initially served as a "nurse plant" to help them survive their first years. Young plants that fall over usually keep their stem intact, and pull out their topmost roots from the ground.
Taller plants sometimes break near the base, leaving the very lowermost part of the stem still connected to its roots. They sometimes keep their stem intact and pull out their topmost roots from the ground, too.
Bighorn sheep have been documented to dine on a barrel cactus in ~13% of their "feeding bouts" in Harquahala Mountain and Little Harquahala Mountain in Arizona, with barrel cactus being a more important item in their diet later in the year when water and fresh vegetation is scarce (Warrick and Krausman 1989 Southwestern Naturalist 34:483.) However, many cactus plants survive the feeding bout, and go on to produce multiple terminal stems. See Bighorn Sheep Herbivory Creates Multiple Heads on Barrel Cacti.
In the Yaqui Meadow area of Borrego Valley, many of the barrels have suffered extensive herbivory at their base, with a large amount of rabbit poop nearby. Although most barrels apparently survive such herbivory, some might succumb.
Decay Rate of Dead Stems. Barrel cacti dead stems don't last long. After four years, they are almost completely decayed.
This plant was alive on 12 December 2020, but was in an advanced state of decay four years later on 12 January 2025. Since we don't know when the cactus fell over, this advanced state of decay was achieved in four years or less.
The interlocking spines appear to be the last remnants of a decaying plant.
Germination. Seed germination occurs after warm summer rains. Jordan and Nobel (1981) found maximal germination in the lab at temperatures of 29° C (84° F). Seedlings grow rapidly in their first 50 days, then more slowly afterward. A one year seedling may be 1.5 cm (0.6 inch) tall (Jordan and Nobel 1981). Seedlings are very vulnerable to drought in their first year, requiring good summer rain to germinate and grow, and then good winter rain to get big enough to survive the next summer's drought until the summer rain returns. Most years in California don't have good enough consecutive rains for seedlings to survive; see the Recruitment section above.
Growth Rate in California. Growth rates measured in California are quite variable. Our measurements so far are given below in rough order of the growth rate.
- 0.5 cm / year (0.2 inches / year) from a plant in Cool Canyon photographed on 12/31/2005 and rephotographed, and measured, on 2/21/2025. The slow growth rate is probably due to the challenging growing conditions this barrel is in, growing in a south-facing boulder, with limited water and soil.
- ~0.9 cm / year (~0.35 inches / year), an estimated growth rate from Jordan and Nobel 1982 (Botanical Gazette 143:511), using field growth measurements over three years, coupled with theoretical growth rates using weather records. They studied a young population at Agave Hill, consisting of plants up to 27 cm (10.6 inches) tall on the north side of the Santa Rosa Mountains. These plants were all growing wider as well as taller. Older plants taller than 27 cm don't increase their width by much, so they may have a different growth rate.
- ~0.8 to ~1.5 cm / year (~0.3 to 0.6 inches / year), measured by Tom from ~20 year repeat photographs of two plants that are now 27 and 37 cm (10.5 and 14.5 inches) tall.
- ~1.5 to ~1.9 cm / year (0.60 to 0.75 inches / year) from a 10 cm (4 inch) tall plant that was first spotted as a ~2.5 cm (~1 inch) plant four to five years earlier (Gaylee and Steve Rogers, private communication).
- ~2.0 cm / year (0.78 inches / year), measured by Tom from 18 year repeat photographs on the Art Smith Trail above Palm Desert. The measured barrel was ~46 inches (1.16 m) tall in 2006, and ~60 inches (1.52 m) tall in 2025.
These growth rates vary from ~0.5 to ~2.0 cm / year (0.2 to 0.8 inches / year).
Interestingly, cultivated seedlings have a very similar growth rate, having a diameter of 1.4 to 1.7 cm (0.4 to 0.5 inches) after one year, with ~six areoles.
For comparison, plants in Arizona were found to grow 3.3 cm per year (1.3 inches / year; Bowers unpubl. data) cited above. No estimate of the growth of California plants comes anywhere close to that value; our growth rates range from 15 to 60 % of the Arizona growth rate.
I've used the maximum California growth rate of 2.0 cm / year to produce the height vs. minimum age shown in Fig. 4; that curve therefore gives the minimum age of a California plant of a given height.
Fig. 4. Height / minimum age relationship for plants in California, using the maximum California growth rate of 2.0 cm / year. Plants with slower growth rates will be older than the number given by this line. The Bowers height / age relationship in Arizona is shown for comparison, for ages 36 and 45. Note that few barrel cacti live to be taller than five feet in California.
Time from Seed Germination to Flowering Plant: "Many years" is the answer most often given! Allyssa Richards is trying to answer that question for plants in the field by carbon dating spines (California Botany Society talk December 12, 2024). Cultivated specimens in "good conditions" start to bloom when their diameter is 15 to 18 cm (6 to 7 inches).
Root system. "At one site, the dry weight of the root system was only 14% that of the above-ground portion. The total area is about 3 times that of the shoot. The total length of the main roots averages 182 m (600 feet)." (Jordan and Nobel 1984). Typically, for plants that have fallen over, one only sees the main taproot, seen on this very young plant and on this older plant. The other roots are only visible when erosion has exposed them. However, this fallen plant still shows a number of its secondary roots.
The roots are shallow, found at depths of 8 to 15 cm (3 to 6 inches), which allows them to begin responding to rains within 24 hours. The perennial roots produce ephemeral rain roots (Jordan and Nobel 1984).
Stems. A barrel cactus is essentially all stem, which is heavily protected by spines. The stem has a number of ribs around its circumference that allow the stems to swell during periods of abundant water without having to increase their surface area. About 6% of the water that enters the stem is stored in the spongy tissue that makes up most of the inside of the stem. (Nobel 1977). We couldn't find what percent of the stem consists of water at its maximum hydration, but it might be something like the 90% water content of a saguaro. Mature plants can lose 81% of their stem water content without dying (Barcikowski and Nobel 1984)!
The ribs usually grow straight up the stem, but occasionally twist in either direction up the stem; see one that twists to the left going up the stem, and one that twists to the right going up the stem. We don't know what causes the twist when it occurs.
Number of stems / branches / heads. Undamaged plants have a single stem, with no branches. Plants with multiple heads at the top of their single stem have been partially eaten by bighorn sheep and survived to grow new "branches" around the edge of the cavity. Plants with multiple heads on the side of their single stem may also have resulted from bighorn sheep herbivory. See Bighorn Sheep Herbivory Creates Multiple Heads on Barrel Cacti.
Heads that arise from the base of the plant are probably caused by herbivory from small animals such as rabbits or hares.
The terminology here is a bit confusing. The new heads are called "branches" since they do branch off the main stem, and when they become long enough, they become columnar and look like branches. However, some of the new heads arise from short stems that actually look more like branches; see the second photo here.
Number of ribs. Barrel cacti have ribs around their circumference that give them the capacity to swell during periods of abundant water without having to increase their surface area. The number of ribs increases as a plant gets older, with young plants having as few as 5 or 8 ribs, and the oldest plants having 21 to 30 ribs. See a young plant with 13 ribs. Growth in the number of ribs occurs in pulses. There are often clear bulges in the diameter of the stem (looking like "love handles" near the waist of some people) when a plant has transitioned from one rib number to another, in order to accommodate the transition between different numbers of ridges.
New ribs are added at the apex of the stem between existing ridges. Since the number of total ribs on a barrel cactus, before and after a transition period, is the sum of the previous number of ribs plus the newly-created ribs, there is some similarity to the Fibonacci sequence. That sequence is constructed by starting with the numbers 1 and 1, and then getting the next number by adding the two previous numbers: 1, 1, 2, 3, 5, 8, 13, 21, 34 ...
Robberecht and Nobel 1982 (Annals of Botany, 51: 153) counted the number of ribs on 100 barrel cacti at the Deep Canyon Desert Research Center, and found about half of the barrels had a Fibonacci number of ribs at mid-height, of 5, 8, 13, or 21 ribs, producing clear peaks in the histogram of the number of ribs.
Every so often we decide to count the number of ribs on some barrels, and usually there are some barrels with a Fibonacci number of ribs, but more that don't have a Fibonacci number. In Henderson Canyon on 4 February 2025, Ted Caragozian counted 15, 18, 19, 20, 21, and 21 ribs on different barrel cacti. The closest Fibonacci numbers are 13 and 21, so this wasn't exactly great correspondence. But the numbers 8, 13, and 21 do seem to come up more often than if the number of ribs were completely random between 8 and 21.
Flowers. Flowers occur on the new growth of the current season, near the top of the barrel, at the top of a mature tubercle, in a felted area adjacent to the spine-bearing part of the areole (Benson, Native Cacti of California). See, for example, Fig. 1 (right) and these pix from: olivier20144; gmgshepherd; and graham11.
The flowers are maroon on the outside (best seen in bud) and bright yellow inside; see this pix by mlgolden.
The flowers are a typical cactus flower, with many perianth parts that are so similar they are called "tepals", since they grade from sepal-like parts on the outside of the flower to petal-like parts on the inside of the flower. The floras don't report the number of tepals, but a rough count from this picture gives a count of 30 or more per flower.
The flowers are diurnal, and may last only a day, but we haven't found a source that gives a lifetime for F. cylindraceus flowers, and we haven't measured it ourselves yet.
The floras report sizes of 3 to 6 cm (1.2 to 2.4 inches) tall and 4 to 6 cm (1.5 to 2.5 inches) wide.
Adaptations to Desert Environment, contributed by Kate Harper
Barrel Cactus is the KING of desert plant adaptations, with 14 (!!!) characteristics that help the plant conserve precious water:
Shape Adaptation
1. Shape with a low surface-to-volume ratio. Its round-to-thick-cylinder shape exposes a minimum of moisture-losing open stomata ("little mouths") to the air IN RELATIONSHIP to the volume of the plant.
Photosynthetic Adaptation
2. CAM Photosynthesis. Barrel Cactus minimizes water loss while stomata are open to take in needed CO2 (carbon dioxide) by opening their stomata ("little mouths") at night when winds have typically calmed, humidity is higher, and temperatures lower.
Leaf Adaptions
3. Leaves modified into Spines. Instead of typical leaves, the Barrel Cactus's leaves have been evolutionarily modified into stiff spines that do not photosynthesize. This means that they have decreased the surface area with moisture-losing open stomata.
4. Modified Leaf Spines that Shade the Stem. The thick, numerous spines cast a partial shade onto the stem. The shade keeps the Barrel Cactus cooler which retains more moisture.
5. Modified Leaf Spines that Increase Effectiveness of Boundary Layer. The spines stick out and break up and slow down the wind affecting the boundary layer.
Stem Adaptions
6. Succulent Stem. Succulent tissue (with 2 types of water-storing cells) allows the Barrel Cactus to save up for NOT rainy days.
7. Photosynthesizing Stem. By concentrating the photosynthetic cells in the stem tissue rather than leaves, the Barrel Cactus has cut down on the water loss from the large surface area of leaves.
8. Sunken Stomata on Stem. By putting each stomata at the bottom of a little pit, the sunken pit acts to increase the effectiveness of the Boundary Layer by protecting the immediate area from wind and concentrating moisture to increase the humidity around the stomata. This slows down moisture loss.
9. Pleated Stem that Shades the Stem. The pleats in the Barrel Cactus stem shade the stem on changing areas of the stem as the sun moves across the sky each day (metaphorically speaking).
10. Pleated Stem that Increases Effectiveness of Boundary Layer. The pleated stem creates a canyon-like protection from wind.
11. Pleated Stem that Enables the Barrel Cactus to Immediately Expand. By being able to expand without having to grow new cells, the Barrel Cactus can take advantage of heavy rain storms when much soil water is available for a brief time. The Barrel Cactus is changing its volume without having to change its surface area!
Epidermal (the outermost layer of cells) Adaptations
12. Thick Cuticle on the Epidermis. The cuticle is a waxy layer that covers the outer surface of the epidermis (outermost cells) and restricts the passage of water and gases into and out of the Barrel Cactus.
Root Adaptations
13. Extensive Shallow Roots. By having numerous shallow roots spread out in a large area, water can be captured even from a small rain event that does not wet the soil very deeply.
14. Ability to grow Rain Roots!. Moisture triggers the fast development of many thread-like additional roots that hugely increase the ability to absorb soil moisture quickly. When the soil dries out, the rain roots shrivel to minimize water loss.
Tallest Specimens of Ferocactus cylindraceus in the Borrego Desert
This table was just begun on 9 January 2025, so it will be a while before it could be considered complete. We began by listing all observed plants more than seven feet tall. But within less than two weeks, repeat observations of them revealed that these tall plants are at the very end of their lifetimes, and fall over and die within one to six years after being found.
Hence on 18 January 2025, we've begun adding specimens over six feet, to see how long those specimens live before falling over. If any reader knows of additional live plants taller than six feet (1.83 m), please let us know about them so we can add them to the table.
While surveying for specimens over six feet tall on slopes above us in Canyon 41 on 24 January 2025, we noticed an interesting phenomenon. We would often spot a candidate in the distance, only to discover that the candidate would appear to shrink whenever one of us approached it! Some specimens would be a foot or two shorter than what we estimated from a distance. Apparently, without a known scale in the pix, such as a human, we overestimated how tall distant cacti on slopes were.
We also eventually realized that there is distortion in most photos of tall barrels with a shorter scale in them that causes the deduced size of the tall barrel in the photographs to be overestimated. Measurements in the field would be significantly smaller than the height that had been deduced from the photos. Examples:
- a barrel that seemed to be 10 feet tall in this observation was actually measured to be 8 feet 4 inches tall, a discrepancy of 22%. This so far is the largest known discrepancy, probably because it had the shortest comparison scale.
- a barrel that seemed to be 7.6 feet tall in this observation was actually just 7.0 feet tall, a discrepancy of 9%. See note 5 in Table 2.
Mark Jorgensen alerted us that Park Ranger George Leetch measured a specimen at a whopping 10 feet 4 inches (10.33 feet) in 1976 in Bisnaga Alta Wash. There is a slide showing the specimen next to Leetch in the archives of ABDSP. We'll try to get a copy of that slide and permission to display that photo here.
There seems to be a gap between specimens that are close to six feet tall, and ones close to seven feet tall, and another gap between ones close to seven feet tall, and ones close to eight feet. These may or may not be real gaps; we need to add more six to seven feet tall specimens to find out whether that gap is real.
For comparison, the Flora of North America gives 300 cm = 3 m = 118 inches = 9.8 feet as the maximum size for this species. Reid Moran photographed a specimen in Baja California that was 308 cm, 10.1 feet tall, assuming the person in the photograph was 69 inches tall.
The Table gives the "Live Date", the first observation of a given living specimen, and then, for specimens that have fallen over, the "Dead Date", the first observation that found the specimen dead. Each date is linked to the iNat observation of that plant on that date. The column "Dead - Live Date" is the difference in those dates, and gives the maximum amount of time that a specimen lived after being first observed. The actual amount of time could be significantly less.
@planetaverde303 created a "FeroAtLeast6feet183cm" field which can be used to tag these specimens at iNat. You can create a map of their locations and easily view each observation. Note that some of the iNat observations are duplicates with the same location. The four Canebrake specimens, and the 1976 10.33 foot specimen, in the table can not be plotted since they don't have coordinates.
Table 2. Tallest Specimens of Ferocactus cylindraceus in the Borrego Desert
| Height (feet) | Height (m) | Location | Photographer | Live Date | Dead Date | Dead - Live Date (yrs) |
|---|---|---|---|---|---|---|
| 10.33 | 3.15 | Bisnaga Alta Wash | George Leetch | 1976 | A long time ago | -- |
| 8.33 | 2.54 | Mountain Springs Grade | Henrik Kibak | 12 January 2025 | ||
| 8.26 | 2.52 | Yaqui Flat | Don Rideout | 12 December 2020 | 12 January 2025 | 4.12 |
| ~8.2 | ~2.5 | Canebrake | Frank Colver | March 2018 | August 2023 | ~5.53 |
| ~8.1 | ~2.5 | Near S2 and Smuggler Wash | Tom Chester | 15 January 2021 | 11 January 2025 | 4.0 |
| ~8.1 | ~2.5 | Jacumba Jim Canyon | Carla Hoegen / Fred Melgert | 10 March 2025 | ||
| ~8.1 | ~2.5 | Mason Valley | Carla Hoegen / Fred Melgert | 3 February 2025 | ||
| 7.33 | 2.23 | Mountain Springs Grade | Don Rideout | 4 March 2025 | ||
| ~7.3 | ~2.2 | Canyon 41 | Tom Chester | 18 November 2018 | 16 January 2025 | 6.24 |
| ~7.21 | ~2.21 | Canyon 41 | Carla Hoegen, Fred Melgert | 17 January 2018 | 25 October 2023 | 5.8 |
| 7.08 | 2.16 | Mountain Springs Grade | Don Rideout | 4 March 2025 | ||
| >7.0 | >2.1 | Canebrake | Karyn Sauber | 23 January 2025 | ||
| 7.005 | 2.135 | Canyon 41 | Tom Chester | 19 February 2024 | ||
| 7.00 | 2.13 | Mason Valley | Don Rideout | 11 January 2025 | ||
| ~6.96 | ~2.16 | Canyon 41 | Carla Hoegen, Fred Melgert | 25 October 2023 | 16 January 2025 | 1.2 |
| 6.58 | 2.01 | Mountain Springs Grade | Tom Chester | 4 March 2025 | ||
| 6.25 | 1.90 | Hornblende Canyon | @obatalov | 17 December 2023 | ||
| 6.25 | 1.90 | Canyon 41 | Don Rideout | 24 January 2025 | ||
| ~6.25 | ~1.90 | sw San Felipe Hills | @planetaverde303 | 8 February 2025 | ||
| ~6.2 | ~1.9 | Canebrake | Karyn Sauber | 27 January 2025 | ||
| ~6.2 | ~1.9 | Canyon 41 | Don Rideout | -- | 24 January 2025 | -- |
| 6.08 | 1.85 | Bisnaga | @planetaverde303 | 8 February 2025 | ||
| 6.08 | 1.85 | Mountain Palm Springs | Tom Chester | 24 January 2025 | ||
| 6.00 | 1.83 | Canyon 41 | Tom Chester | 16 January 2025 | ||
| 6.00 | 1.83 | Lower Smuggler Canyon Wash | Don Rideout | 11 January 2025 | ||
| ~6.00 | ~1.83 | Canebrake | Karyn Sauber | -- | 21 January 2025 |
Measurements not made by using a tape measure on a live specimen are given as only approximate, using "~" in front of the number, and only to one decimal place. Even measurements made on live plants from pix with a person beside the cactus for a scale are given as only approximate due to distortion in most photos of tall barrels with a shorter scale in them.
The length of fallen plants might be greater than the height of live plants for at least three reasons. They decompress, since they no longer have their own weight pushing them down and making them shorter when standing. Even humans are a cm or so taller in the morning than in the evening, after lying in bed at night. When barrel cacti fall, they also might stretch along the uneven ground, due to tension in the stem from rocks and other objects on the ground. The stem might elongate from cracking. Older fallen plants might have some shrinkage as they dry, although examination of dead plants makes that seem unlikely.
1 I originally measured 8.9 feet by comparing the fallen-over plant to Fred Melgert's height in their photo #2. To my shock, I measured 7.25 feet in the field on 24 January 2025 (see Don's obs and the notes in my obs). The height of the dead plant must have been exaggerated by having the cactus closer to the camera than Fred was, and also by Fred not lying perfectly straight on the uneven and rocky ground surface. There is still considerable uncertainty in the new number of 7.25 feet since the height of the plant after it fell might be larger than it was when it was standing.
2 Probably dead within a year of its first observation, due to its advanced state of decay when followed up four years later.
3 Probably would have died earlier if it hadn't been staked upright.
4 Probably was dead two years earlier or so due to its state of decay.
5 I originally measured 7.60 feet for the height by comparing the plant to the height of Tom White. I was again shocked in the field when a measurement with a tape measure gave a height of 84 inches, 7.0 feet. Part of this 9% discrepancy might be explained by not knowing exactly where the base of the cactus was, since it isn't seen well in the pix and was complicated by the lean of the cactus from vertical. We noted that the base was an inch or two above the ground, due to the lean. Also, part of the discrepancy might be caused by the cactus being a bit closer to the camera than Tom was.
We later realized that most of this discrepancy was due to distortion in most photos of tall barrels with a shorter scale in them.
6 I originally measured 7.44 feet using the photograph with Fred Melgert as the scale. The downed plant was measured as 6.75 feet, and 6.92 feet, on different days, with the variance probably caused by how one measured the two parts of the broken cactus, and how well the tape measure followed the curvature of the downed cactus.
There appear to be clusters of plants at heights of 6 to <6.25 feet; 7 to <7.25 feet; and 8 to <8.25 feet; see a histogram of the heights made on 13 March 2025. Since these measurements are made to the nearest inch for measured specimens, and since there is no bias toward integer feet in measuring heights from photographs, it seems unlikely these peaks in the histogram are artificial. Presumably, it reflects the years in which those specimens were established.
So far, the largest number of specimens is from Canyon 41, with 7, then Mountain Springs Grade, with 4. Canebrake also has 4 specimens, but they may have been planted there.
Measurements of Height and Width
As of 7 March 2025, we have measured 168 specimens of Ferocactus for their height and width. A plot of the width vs. height is shown in Fig. 5.
Fig. 5. Measured height and widths for all specimens, including ones incidentally encountered.
Our plants essentially stop growing significantly in width when they reach a height of about 30 inches (75 cm). Plants 30 to 60 inches tall have widths of 10 to 14 (16) inches. Plants 60 to 100 inches tall have widths of 11 to 15 inches, just about an inch wider on average.
The small variation in width for the taller plants allow heights to be deduced from measurements of the height to width ratio in photographs. Fig. 6 shows the ratio of the height to width plotted as a function of height, for the same 168 specimens shown in Fig. 5.
Fig. 6. Ratio of the height to width plotted as a function of height.
Taxonomy and Phylogeny
The genus Ferocactus was defined by Britton & Rose in 1922 (Cact. 3:123). Plants now in Ferocactus were formerly treated under Echinocactus. The two genera have different fruit and flower characteristics.
Our F. cylindraceus was formerly called Echinocactus acanthodes, defined by Lemaire in 1859 (Cact. Gen. Nov. Sp. p. 106) (although the date is given as 1839 in Britton & Rose). Engelmann published the name Echinocactus viridescens cylindraceus in 1852, considered the correct basionym for our plants. Engelmann then promoted it to the species E. cylindraceus in 1856.
The name F. cylindraceus was published by Orcott in 1926 (Cactography 1926(1):5).
Benson defined five varieties of F. cylindraceus, with two of the varieties in California, which were distinguished by the length of the spines, the widths of the tepals, and the size of the seed, with var. lecontei having slightly shorter spines and smaller seeds, and slightly wider perianth parts, than var. cylindraceus. However, the Flora of North America treatment did not recognize any of the five varieties, saying they were "not consistently distinguishable". There also appears to be no geographic separation between the two varieties in California in Benson's map of them.
The type locality for F. cylindraceus is from our area: "Found near San Felipe, on the eastern slope of the California mountains". The modern name for that locality is the southern San Felipe Hills, where specimens of this species are abundant. See Tom's iNat posts of that area with its dense population of barrels.
Our plants were called F. acanthodes before 1979, when Taylor pointed out that name was ambiguous since it was based on a small plant of unknown origin, with the original specimen lost.
There are some 25 to 30 species in the genus Ferocactus, with a small number of species not accepted by some authorities. All of the Ferocactus species grow in Mexico. Five of those species have part of their range into the southwest United States and Texas.
The closest relative to F. cylindraceus is F. wislizeni, found in central Arizona and eastward, whereas F. cylindraceus is found in south-central Arizona and westward. The two species differ on whether the seeds are pitted or not; their flower colors; the degree to which the central spine is hooked; the degree to which adult plants lean southward; and flowering time.
The latest phylogenetic study found that Ferocactus was polyphyletic concerning Glandulicactus, Leuchtenbergia, Stenocactus and Thelocactus (Vazquez-Sanchez et al 2013).
The rest of this page is mostly historical, but showing interesting differences in widths of barrels in two places.
So far, we have measured the height and width for all specimens in a small area for two places, 17 plants from Rainbow Canyon Wash, and 21 plants from an area just north of S2 and just east of Smuggler Canyon Wash. The Rainbow Canyon Wash area was arbitrarily selected. The Smuggler area location was picked because it had a very tall specimen, 8.12 feet tall, in the past. That specimen was not measured, since it was newly-dead.
The measurements are given in Fig. 7, separately for the two areas, and with disturbed plants, mostly non-erect plants, noted. All measured plants had produced flowers in the past, as evidenced from the presence of dried flowers, or the presence of extrafloral nectaries on the areoles.
Also shown are the sizes given in the Flora of North America treatment, (20-) 45-150 (-300) x (20-) 25-40 (-50) cm. Those sizes are represented by a straight line in Fig. 7, as well as a box for the typical size of 45-150 x 25-40 cm, and separate boxes for the rarer smaller plants of 20-45 x 20-25 cm, and the rarer larger plants of 150-300 x 40-50 cm. The sizes in inches are (8-) 18-59 (-118) x (8-) 10-16 (-20) inches.
Interestingly, almost all the undisturbed plants from Rainbow Canyon Wash fall in one side of the "typical" FNA measurement box, the side where the width is greater than typical for their height, whereas almost all the plants from the Smuggler area fall on the other side of the line, where the width is less than typical for their height! Don speculated that the plants in Rainbow Canyon Wash were well-hydrated, from the 11 August 2024 monsoonal thunderstorm there, whereas the plants near Smuggler Canyon Wash were dehydrated from the very long interval without rain there. If so, the Rainbow plants have a typical diameter about 10% greater than average, and the Smuggler plants a typical diameter about 10% less than average. To see if this made sense, we tried to find quantitative info from others on the variation in diameter with hydration, without success.
After it rains a decent amount this season, if it rains, we'll remeasure some of the Smuggler plants to see if they have gotten fatter.
It is also notable that two of the three disturbed plants from Rainbow Canyon Wash are on the other side of the "typical" line from the undisturbed plants from there.
Fig. 7. Measured height and widths for undisturbed plants, and specimens that were disturbed, from two locations, along with the sizes given in the Flora of North America (FNA) treatment (see text). All specimens had produced flowers in the past.
Additional measurements of plants measured incidentally in other areas are included in Fig. 8. Only the smallest specimen showed no evidence of producing flowers so far in its lifetime.
Fig. 8. Measured height and widths for all measured specimens, including ones incidentally encountered. Only the smallest specimen showed no evidence of producing flowers so far in its lifetime.
Details on Measurements of 17 specimens in Rainbow Canyon Wash
These measurements were made by Tom, so the "I" refers to him in this section.
I was stimulated to measure some specimens after seeing the large number of very young plants of F. cylindraceus on the PCT north of Scissors Crossing. I was curious as to what the distribution in height was for the entire population. The next place I went was Rainbow Canyon wash, so I measured specimens there.
I was surprised that all the F.c. plants I measured in Rainbow Wash were plants that were mature enough to have flowered, with no very young plants in the stretch of wash I covered. Those F.c. plants were not very abundant in the wash. They became more abundant as I entered the canyon proper, but I had reached my measuring limit by then.
I measured all the specimens I could easily reach in about a 1/4 mile distance below the mouth of Rainbow Canyon. Three specimens were guarded by Agave plants et al, so I skipped measuring them. Those appeared to be typical specimens, but I couldn't get close enough to them to see if they had little stems at their base.
The 17 specimens I measured ranged from 11 to 67 inches (28 to 170 cm) in height, and 9 to 16 inches (23 to 41 cm) in width; see pictures of the smallest one. The two largest ones had fallen over; see below. I measured the plants in inches simply because I had a 12 foot long compact tape measure that only had markings in inches.
13 of those 17 specimens were single erect stems, with no stem branches anywhere on the plant, indicating that they were undisturbed and growing naturally; see photos of one example. One of those 17 specimens had a single erect stem, but also had four short stem branches at its base; see pictures. None of these 14 specimens had any significant departure from being strictly erect; i.e., they weren't leaning toward the sun like its sister species F. wislizeni is reported to do.
Three of those 17 specimens had been disturbed in some way:
- One plant had fallen over, with 30" (76 cm) of its lowermost stem lying on the ground, with its top 37" (94 cm) curving up from the ground. It had two additional short stem branches at its base, with an additional one stem branch just above where the stem curved upward from lying on the ground. See pictures.
- One plant was uprooted a bit by channel erosion, but was still mostly erect, with three stem branches at base. See pictures.
- One plant was partially fallen over, making about a 30 degree angle with the ground. See pictures.
There were a number of much taller plants on the canyon slopes that were outside the area in which I measured plants.
Details on Measurements of 22 specimens near Lower Smuggler Wash
Both authors measured 22 specimens from a small area on 11 January 2025.
(More text TBS).
We thank Kate Shapiro and Fred Melgert for comments that have improved this page.