Maxipiñon: One of the Rarest Pines in the World

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The maxipiñon (Pinus maximartinezii) is one of the rarest pines on Earth. A native of southern Sierra Madre Occidental, Mexico, nearly all individuals of this species can be found scattered over an area that collectively spans only about 3 to 6 square miles (5 – 10 km²) in size. Needless to say, the maxipiñon teeters on the brink of extinction. As a result, a lot of effort has been put forward to better understand this species and to develop plans aimed at ensuring it is not lost forever.

The maxipiñon has only been known to science for a few decades. It was described back in 1964 after botanist Jerzy Rzedowski noted some exceptionally large pine seeds for sale at a local market. He named the species in honor of Maximino Martínez, who contributed greatly to our understanding of Mexican conifers. However, it was very obvious that the maxipiñon was well known among the residents of Zacatecas.

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The reason for this are its seeds. The maxipiñon is said to produce the largest and most nutritious seeds of all the pines. As such, it is a staple of the regional diet. Conversations with local farmers suggest that it was much more common as recent as 60 years ago. Since then, its numbers have been greatly reduced. It soon became apparent that in order to save this species, we had to learn a lot more about what threatens its survival.

The most obvious place to start was recruitment. If any species is to survive, reproduction must outpace death. A survey of local markets revealed that a lot of maxipiñon seeds were being harvest from the wild. This would be fine if maxipiñon were widespread but this is not the case. Over-harvesting of seeds could spell disaster for a species with such small population sizes.

Indeed, surveys of wild maxipiñon revealed there to be only 2,000 to 2,500 mature individuals and almost no seedlings. However, mature trees do produce a considerable amount of cones. Therefore, the conclusion was made that seed harvesting may be the single largest threat to this tree. Subsequent research has suggested that seed harvests actually may not be the cause of its rarity. It turns out, maxipiñon population growth appears to be rather insensitive to the number of seeds produced each year. Instead, juvenile tree survival seems to form the biggest bottleneck to population growth.

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You see, this tree appears to be more limited by suitable germination sites than it does seed numbers. It doesn’t matter if thousands of seeds are produced if very few of them ever find a good spot to grow. Because of this, scientists feel that there are other more serious threats to the maxipiñon than seed harvesting. However, humans are still not off the hook. Other human activities proved to be far more damaging.

About 50 years ago, big changes were made to local farming practices. More and more land was being cleared for cattle grazing. Much of that clearing was done by purposefully setting fires. The bark of the maxipiñon is very thin, which makes it highly susceptible to fire. As fires burn through its habitat, many trees are killed. Those that survive must then contend with relentless overgrazing by cattle. If that wasn’t enough, the cleared land also becomes highly eroded, thus further reducing its suitability for maxipiñon regeneration. Taken together, these are the biggest threats to the ongoing survival of this pine. Its highly fragmented habitat no longer offers suitable sites for seedling growth and survival.

As with any species this rare, issues of genetic diversity also come into play. Though molecular analyses have shown that maxipiñon does not currently suffer from inbreeding, it has revealed some interesting data that give us hints into the deeper history of this species. Written in maxipiñon DNA is evidence of an extreme population bottleneck that occurred somewhere between 400 and 1000 years ago. It appears that this is not the first time this tree has undergone population decline.

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There are a few ways in which these data can be interpreted. One is that the maxipiñon evolved relatively recently from a small number of unique and isolated individuals. Perhaps a hybridization event occurred between two closely related piñon species - the weeping piñon (Pinus pinceana) and Nelson piñon (Pinus nelsonii). Another possibility, which does not rule out hybridization, is that the maxipiñon may actually be the result of artificial selection by agriculturists of the region. Considering the value of its seeds today, it is not hard to imagine farmers selecting and breeding piñon for larger seeds. It goes without saying that these claims are largely unsubstantiated and would require much more evidence to say with any certainty, however, there is plenty of evidence that civilizations like the Mayans were conserving and propagation useful tree species much earlier than this.

Despite all we have learned about the maxipiñon over the last few decades, the fate of this tree is far from secure. Ex situ conservation efforts are well underway and you can now see maxipiñon specimens growing in arboreta and botanical gardens around the world. Seeds from these populations are being used for storage and to propagate more trees. Sadly, until something is done to protect the habitat on which it relies, there is no telling how long this species will last in the wild. This is why habitat conservation efforts are so important. Please support local land conservation efforts in your area because the maxipiñon is but one species facing the loss of its habitat.

Photo Credits: [1] [2] [3] [4]

Further Reading [1] [2] [3]

Something Strange in Mexico

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I assure you that what you are looking at here is indeed a plant. I would like you to meet the peculiar Lacandonia schismatica, one of roughly 55 species belonging to the family Triuridaceae. Not a single member of this family bothers with leaves or even chlorphyll. Instead, all members are mycoheterotrophic, meaning they make their living by parasitizing fungi in the soil. However, that is not why L. schismatica is so strange. Before we get to that, however, it is worth getting to know this plant a little bit better.

The sole member of its genus, Lacandonia schismatica grows in only a few locations in the Lancandon Jungle of southeastern Mexico. Its populations are quite localized and are under threat by encroaching agricultural development. Genetic analyses of the handful of known populations revealed that there is almost no genetic diversity to speak of among the individuals of this species. All in all, these factors have landed this tiny parasite on the endangered species list.

Mature flower of  Lacandonia schismatica . Three yellowish anthers (center) surrounded by rings of red carpels. Scale bar = 0.5cm.”  [SOURCE]

Mature flower of Lacandonia schismatica. Three yellowish anthers (center) surrounded by rings of red carpels. Scale bar = 0.5cm.” [SOURCE]

To figure out why L. schismatica is so peculiar, you have to take a closer look at its flowers. If you knew what to look for, you would soon realize that L. schismatica appear to be doing things in reverse. To the best of our knowledge, L. schismatica is the only plant in the world that known to have an inverted flower arrangement. The anthers of this species are clustered in the center of the flower surrounded by a ring of 60 or so pistils. The flowers are cleistogamous, which means they are fertilized before they even open, hence the lack of genetic diversity among individuals. 

Not all of its flowers take on this appearance. Researchers have found that in any given population, a handful of unisexual flowers will sometimes be produced. Even the bisexual flowers themselves seem to exhibit at least some variation in the amount of sexual organs present. Still, when bisexual flowers are produced, they only ever exhibit this odd inverted arrangement.

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It is not quite clear how this system could have evolved in this species. Indeed, this unique floral morphology has made this species very hard to classify. Genetic analysis suggests a relation to the mycoheterotrphic family Triuridaceae. It was discovered that every once in a while, a closely related species known as Triuris brevistylis will sometimes produce flowers with a similar inverted morphology.

This suggests that the inversion evolved before the Lacandonia schismatica lineage diverged. One can only speculate at this point. The future of this species is quite uncertain. Climate change and habitat destruction could permanently alter the conditions so that this plant can no longer exist in the wild. This is further complicated by the fact that this species has proven to be quite difficult to cultivate. Only time will tell. For now, more research is needed on this peculiar plant.

Photo Credit: [1] [2] [3]

Further Reading: [1] [2] [3] [4]

The Pima Pineapple Cactus

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The Pima pineapple cactus (Coryphantha robustispina) is a federally endangered cactus native to the Sonoran Desert. It is a relatively small cactus by most standards, a fact that can make it hard to find even with a trained eye. Sadly, the plight of this cactus is shared by myriad other plant species of this arid region. Urbanization, fire, grazing, and illegal collection are an ever present threat thanks to our insatiable need to gobble up habitat we should never have occupied in the first place. 

Deserts are lands of extremes and the Pima pineapple cactus seems ready for whatever its habitat can throw its way (naturally). Plants are usually found growing individually but older specimens can take on a clustered clonal habit. During the winter months, the Pima pineapple cactus shrivels up and waits until warmth returns. Come spring, the Pima pineapple cactus begins anew. On mature specimens, flower buds begin to develop once the plant senses an increase in daylight. 

The flower buds continue to develop well into summer but seem to stop after a certain point. Then, with the onset of the summer monsoons, flower buds quickly mature and open all at once. It is thought that this evolved as a means of synchronizing reproductive events among widely spaced populations. You see, seed set in this species is best achieved via cross pollination. With such low numbers and a lot of empty space in between, these cacti must maximize the chances of cross pollination.

If they were to flower asynchronously, the chances of an insect finding its way to two different individuals is low. By flowering together in unison, the chances of cross pollination are greatly increased. No one is quite sure exactly how these cacti manage to coordinate these mass flowering events but one line of reasoning suggests that the onset of the monsoon has something to do with it. It is possible that as plants start to take up much needed water, this triggers the dormant flower buds to kick into high gear and finish their development. More work is needed to say for sure.

Seed dispersal for this species comes in the form of a species of hare called the antelope jackrabbit. Jackrabbits consume Pima fruits and disperse them across the landscape as they hop around. However, seed dispersal is just one part of the reproductive process. In order to germinate and survive, Pima pineapple cacti seeds need to end up in the right kind of habitat. Research has shown that the highest germination and survival rates occur only when there is enough water around to fuel those early months of growth. As such, years of drought can mean years of no reproduction for the Pima.

Taken together, it is no wonder then why the Pima pineapple cactus is in such bad shape. Populations can take years to recover if they even manage to at all. Sadly, humans have altered their habitat to such a degree that serious action will be needed to bring this species back from the brink of extinction. Aside from the usual suspects like habitat fragmentation and destruction, invasive species are playing a considerable role in the loss of Pima populations. 

Lehmann lovegrass (Eragrostis lehmanniana) was introduced to Arizona in the 1930's and it has since spread to cover huge swaths of land. What is most troubling about this grass is that it has significantly altered the fire regime of these desert ecosystems. Whereas there was once very little fuel for fires to burn through, dense stands of Lehmann lovegrass now offer plenty of stuff to burn. Huge, destructive fires can spread across the landscape and the native desert vegetation simply cannot handle the heat. Countless plants are killed by these burns.

Sometimes, if they are lucky, large cacti can resprout following a severe burn, however, all too often they do not. Entire populations can be killed by a single fire. What few plants remain are frequent targets of poaching. Cacti are quite a hit in the plant trade and sadly people will pay big money for rare specimens. The endangered status of the Pima pineapple cactus makes it a prized target for greedy collectors. 

The future of the Pima pineapple cactus is decidedly uncertain. Thankfully its placement on the endangered species list has afforded it a bit more attention from a conservation standpoint. Still, we know very little about this plant and more data are going to be needed if we are to develop sound conservation measures. This, my friends, is why land conservation is so important. Plants like the Pima pineapple cactus need places to grow. If we do not work harder on setting aside wild spaces, we will lose so much more than this species. 

Photo Credits: [1] [2] [3]

Further Reading: [1] [2] [3]

Common Yet Endangered Palms

Raise you hand if you have ever had a parlor palm (Chamaedorea elegans). I see most of you have raised your hands. Palms in the genus Chamaedorea are the most commonly kept palms on the market. They are small, very shade tolerant, and nearly indestructible. The clear winner in this regard is the parlor palm. We have all given these little palms a shot at one time or another. They are so common that we rarely give a second thought as to where they come from. Surely they did not evolve in a nursery. It may surprise you that for as ubiquitous as these palms are, they are actually quite threatened in the wild.

The genus Chamaedorea is endemic to sub-tropical forests of the Americas and is comprised of roughly 80 species. They are understory palms that are most at home under the deep shade of the canopy. Most species are generally pretty small, rarely growing over 10 feet. All of these factors add up to some resilient and fun houseplants. It doesn't take much to keep them happy. Every once in a while they will produce flowers. Though small, they are often brightly colored. The preferred method for mass cultivation is via seed. However, seed production outside of their native range is notoriously difficult and often requires human intervention. For this reason, a vast majority of nursery grown palms are grown from wild collected seeds.

This may not seem like a bad deal until you look at the numbers. I have seen reports of over 500 million seeds exported from Mexico annually. Couple this with the fact that many species of Chamaedorea are known to grow in very restricted ranges and suddenly the picture becomes very bleak. Over collecting of seeds has decimated wild populations. Without seeds there is no recruitment, no seedlings to take the place of adult plants.

Another considerable threat to these palms comes from the cut flower industry. Palm fronds are notoriously gorgeous and many people like to include them in their displays. Most of the leaves cut come from wild plants. Normally palm fronds are harvested in a manner that doesn't kill the plant, however, in Mexico children are often employed to collect them and their lack of experience can severely damage wild populations.

On top of all of this, the forests in which these palms grow are now being converted to agriculture. If actions are not taken to limit the abuse of wild populations, it is likely that some of the most commonly encountered house plants are going to be extinct in the wild. This is a hard pill to swallow. If you have any of these species growing in your home, take care of them. Perhaps knowing how uncertain the future is for many of these palms will earn them a little more respect.

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Here is a list of some of the most threatened species in this genus:

Chamaedorea amabilis
Chamaedorea klotzschiana
Chamaedorea metalica
Chamaedorea pumila
Chamaedorea sullivaniorum
Chamaedorea tuerckheimii

Photo Credits: Michael Wolf (http://bit.ly/16suMsf), scott.zona (http://bit.ly/1zHdUII),

Further Reading:
http://bit.ly/1ADC3mw