Thanksgiving this year was spent road-tripping through Baja California, with botany on the brain. What’s new? Two plants really stuck out, dotting the landscape along most of our route. Looking back at photos, they really felt like buddies, plant buddies of the Baja. Who are they? The Boojum and ever present cacti!

Starting from Tecate, and down the Pacific side of the peninsula, and almost reaching the halfway mark of the peninsula, then back up the Gulf side, meant lots of time to look out the window and soak it all in. Additionally, the long off-trail day hikes meant more time observing the funky new-to-me plants.

The Baja peninsula, at least the northern half, (I can’t yet speak to the bottom half) is expansive, wild, and pretty much totally empty from human establishments. Perhaps surprisingly to most, the Baja is incredibly, incredibly, incredibly biodiverse. It has “700 plant endemic species, 25 endemic species of terrestrial fauna, and 740 marine endemic species with 40% of all marine mammals in the world” (Convention on Biological Diversity).

en-dem-ic

of a plant or animal, native and restricted to a certain place.

Oxford Dictionary

At times during our long walks, it really felt like I was in an imaginary land inside Dr. Suess’s mind. The equivalent to the Truffula trees was the Boojum tree, a common name that’s as fun spoken as written. Boojum trees dotted the landscapes at various densities throughout most of our travels in Baja California, and they were always next to a diverse array, in sizes and shapes, of cacti!

This trip was like most of our other trips where we saw sooo much in such a short amount of time that I now find myself with the time to learn and process what I saw. So, today’s blog post is my interpretation of the natural history of Boojum Trees, and the cacti that we came across, that were, in my perspective, tall plant buddies of Baja California. 

Boojum Tree

If you are thinking the Boojum tree resembles an ocotillo (pictured below), you’re on the right track, as it’s a member of the Ocotillo family (Fouquieriaceae). The Boojum tree thrives in various habitats within the Baja Peninsula, which it’s nearly endemic to. Except for some populations in mainland Mexico, which were thought to be brought over by the Seri Indigenous Peoples.

The characteristic thick grayish-white bark and stout tapering trunk can reach up to 20m in height, the tallest is 26.4m in height. Holy cow! That’s over 86 feet! Imagine stacking roughly 14, six-foot people on top of each other!

Throughout the trunk, spiny pencil-like branches extend outward, which host thin green to blue-green obovate leaves. Rain means growth for Boojum trees, which is when leaf and mass growth occurs. Leaves drop in dry times, and this pattern is known as a plant being drought-deciduous. 

At the tips of the branches from July to August gorgeous clusters of creamy-white tubular flowers appear, which apparently smell like honey! Flowers attract various pollinators like flies, bugs, and hummingbirds. Meanwhile, spiders lurk in the shadows, waiting to ambush their insect prey who seek the nectar. 

Notable desert-dwelling adaptations include the thick thick bark which is essentially resistant to animal penetration. Plants with thick, giant, fleshy stems are called sarcocaulescent. However, two types of lifeforms get through, one being parasites, and the other being ball-moss and boojum-net lichen epiphytes who hang out on the trunk and branches. 

It’s good to note the Spanish name for the boojum tree is “cirio,” which means ‘candle’ in English due to its resemblance to tall wax candles.

Cacti

Mexican Giant Cactus, Pachycereus pringlei

iNaturalst: Near-ish La Lomita

Starting off with a banger, a big boy banger at that. While Mexican Giant is a great name, but the Spanish name Cardón seems to be what most people call it.

Cardóns can reach up to 20m tall! Muy alto! That’s 65 feet! To support all that height, the trunks are thick, up to 1.5m wide, which can relate to up to 10 tons. These cacti can be over 200 years old!

Adaptations to growing in the various Sonoran desert ecoregions include: storing water in the stem, causing the stem to swell and appear flesh/succulent. The ribs of the cactus stem allow for expansion when it stores excess water for later dry spells. Without leaves, the green stems are the site of photosynthesis. Below the soil’s surface, its shallow root system allows water to be slurped up quickly whenever the rare rain events arrive.

Bats pollinate the Cardón’s white flowers at night, but during the day, birds and bees will also take advantage of the abundant pollen and nectar. Other animals arrive when the fruit is ripe, including mammals, bats, and birds which help disperse the seeds within the red or white flesh. As true trees are a rarity in the Baja, hawks take advantage of the Cardón’s height and stability and build their nests in the higher branches.

Indigenous Peoples utilize many parts of the Cardón. It was both a food source and a source of materials for “fishing spears, poles, beds, fences, corrals, house walls, and rafters (Baja Plant Field Guide). Both the fruit and seeds are consumed via various methods, and the flesh is also a source of medicine by ranchers.

Candelabra Cactus, Myrtillocactus cochal

iNaturalist: San Gregorio Ranch

Candelabra is a great common name, as you can see. It can grow up to 3m (10ft) tall, as well as wide, and grows all along the Baja.

Anatomically, it has 6-8 rounded ribs, with “marble-sized, globose fruit,” which is edible, and consumed by the Indigenous Peoples, apparently its flavor is “currant-like.” But today, it’s used for making “drinks, candy, empanadas, and marmalade (Baja California Plant Field Guide).

Senita Cactus, Lophocereus schottii

iNaturalist: Near-ish La Lomita

While these photos only show 6-20 shoots, this species can have up to 100! Each shoot has 4-13 ribs, which are quite prominent. That top bristly balaclava-esc hat of spines is called the terminal pseudocephalium, which can get up to 1 meter long.

While we found this one with fruit that some critters enjoyed, apparently it’s not usually chosen to eat by us humans.Like other flowering plants of desert regions, this cactus is only pollinated by one species, the senita moth. This moth requires the cacti throughout its lifecycle; eggs are laid in various parts of the flower, the larvae crawl towards the flower’s ovary and eats it, and overwinters inside. It pupates in the cactus stem, and after adults emerge they feed on the flowers, unknowingly collecting pollen which then pollinates the cacti. Additionally, the adults mate and hang out on the cactus spines. This relationship is called obligate mutualism.

Stenocereus thurberi ssp. thurberi

iNaturalist: San Gregorio Ranch

This cactus is a subspecies of the Organ Pipe Cactus, Stenocereus thurberi. This is one of two subspecies based on its distribution and height. S thurberi is found in Mexico and in the US in rocky deserts. Depending on where it is throughout its range determines how trunk-y or branched it is.

It has a white to cream flower that is mostly bat-pollinated, so it opens at night.

Its fruits are tennis ball-sized, and taste like watermelon. According to the Baja California Plant Field Guide, when the fruit ripens, for a period of about two months out of the year, it causes a “state of euphoria” in the Indigenous population because otherwise they were “generally hungry,” according to missionary records. During harvest time, groups would travel and mix with other groups, which was a time to establish “the social and religious structure of their society.”

Ponderings. . .

Clearly, this tall and thick morphology provides great adaptations to living in the harsh, demanding, and diverse conditions within the Baja peninsula and beyond. The ability to slurp up water when available, to expand, and to hold onto it for later makes total sense in a desert ecosystem, but why the height? The desert can be very windy, so the thickness of the branches and trunks of the cacti and Boojum tree keeps it stable in one place. But there must be more evolutionary and natural history reasons. . .

Perhaps being tall provides a slight advantage to signal to pollinators from afar like “hey, hey I have juicy nectar for you, come visit meee!” Creating flowers is an expensive endeavor, so of course a plant wants to maximize the use of its flowers to ensure reproduction.

A larger and “fatter” plant means less surface area for photosynthesis, gas exchange, and heat loss compared to a “skinnier” plant of the same mass. In a desert ecosystem, managing heat loss is of the utmost importance. On a similar thought trail, desert plants have smaller leaves because smaller leaves don’t get as hot as larger leaves, which are bigger and thicker. So I’d imagine it’s a similar scenario for our lanky desert pals. The larger, denser mass plants, the more potential to overheat. Think about it, I’m not aware of really large round cacti in this ecosystem.

Flowing along with that train of thought, it makes me think about barrel cactus, which are much more. . . well. . . barrel-shaped! I’ve seen keel-ed over cactus with giant chunks taken out the sides, perhaps a critter was able to enter and excavate the insides. With a fatty frame, there would be more edible goods in one area in a rotund plant than a tall and skinny one. That’s not to say critters don’t go for the tall cacti, woodpeckers and other animals make homes within their branches, but it’s in the interest of the animal to not entirely kill the plant.

Additionally, we got a glimpse of the dense fog that rolls through parts of the Baja on a few days of our trip. Cactus spines and Boojum branches catch the fog, in turn dripping the water along the trunk, making it available to the cells to soak up. So, it’s easy to imagine how a cacti or Boojum tree that grows above its surrounding neighbors can take advantage of the open arial space to grab the available fog. Additionally, the greater height would mean more surface area for the drips to drip down and a higher chance for it to be absorbed into the plant.

In conclusion. . .there is no conclusion. . .

Thanks for reading my thinkings and thoughts on this topic, usually these ramblings get jotted into my nature journal, but right now I’m all about reminding myself that adults. . .aka me, need play time too. These blogs are my current mental playtime. Hope you enjoyed my dive into exploring a few tall and lanky plant buddies of Baja California.

Happy Botanizing!

Resources & References:

• Baja California Plant Field Guide
• Upiga Senita Moth, Wikipedia page
• World of Succulents, Myrtillocactus cochal
• Heat Beating Desert Adaptations of the Cactus, Nature Comes Standard