Wow - neat trick, Pachycereus.

[KarenRei]

I wish more plants had figured this one out!

Right now I'm in the middle of researching good edible cactus.  And honestly, Pachycereus pringlei (Cardón) isn't at the top of the list.  It's not that the fruits are tasteless or insipid like many cactus fruits - they're sort of like molasses flavoured, somewhat dry saguaro fruits.  But it's one of those cacti that has to get big to fruit, like its Saguaro cousins (at least it's faster growing than Saguaros!). It's likely the largest cactus in the world, nearly 20 meters tall and over a meter in trunk diameter. Extremely massive; you don't want to run into something like this with your car. 



But that's not what I felt the need to mention. 

We all know of plants that have symbiotic relations with nitrogen-fixing bacteria.  They release chemicals in the soil which encourage the microbes to migrate toward them, then enclose them in nodules, where they nurture them. We also know other plants that form root associations with mycorrhizal fungi; if these fungi are in the soil, the fungus infests the plant's roots, "stealing" sugars, but in exchange breaking down bound-up minerals in the soil for the plant to use.  P. pringlei takes it a step further. It can grow on bare rock because of its associations with nitrogen-fixing bacteria and rock-decomposing fungi, but it can do so anywhere because it packages these bacteria and fungi into its seeds.  Which I guess is a big advantage in a desert; things are so sparse, you can't count on the "soil" just happening to have what you need on-hand!  A bird eats the fruit, leaves its droppings with the seeds some great distance away, and it's guaranteed to have the helper species it needs on-hand.

Has anyone ever heard of any other plants doing this?

[nullzero]

I have tried a small amount of the fruit in the wild in Mexico. The fruit is pretty large, but those spines are really annoying also the seeds are really large for a cacti. At least the outer shell is not to hard to remove with tools. The colors of the flesh is really nice red, magenta, and purple. I talked to the locals they do not normally eat them, because there is much better fruit available around the same time Stenocereus sp. I tasted a small amount of semi dried its pretty sweet tasting with not to much depth of flavors, I would say its average in taste. Fruiting season is in May to June.

The ancient indigenous tribes semi cultivated these cacti in Mexico near Jalpa, MX, the pictures are taken at an ancient civilization site.

[KarenRei]

Thanks for the fruit review!  "average" seemed to be a pretty general sense I'd been getting,  but I hadn't come across the seed complaint before - good to know. 

Funny about the spines, the closely related P. pecten-aboriginum is called "Indian Comb" because locals tribes reportedly removed the spines on part of a fruit, then used it as a hairbursh 

[luketrollope]

Very interesting Karen. Do you have any more information on how the bacteria and fungi and passed along with the seed? Are the spores/ bacteria embedded in the seed or on the seed surface? It got me thinking about a plants microbiome and how that may effect the the well being of a plant. I wonder if it would be possible to inoculate seeds of other species with the same fungi and bacteria so they too could grow in poor quality soil?    Thanks

[KarenRei]

Very interesting Karen. Do you have any more information on how the bacteria and fungi and passed along with the seed? Are the spores/ bacteria embedded in the seed or on the seed surface? It got me thinking about a plants microbiome and how that may effect the the well being of a plant. I wonder if it would be possible to inoculate seeds of other species with the same fungi and bacteria so they too could grow in poor quality soil?    Thanks

Unfortunately, no, I don't have any information on how it achieves this - just that it does so on order to take its associated species along for the ride when its seeds are spread.

[Mike T]

Nitrogen and even phosphorous  fixing through micro-organism in plants is pretty common and not unique to cacti.There are thousands of mycorrhiza species,most plants have them and they date back hundreds of millions of years. The vesicle forming types are endomycorrhiza. Ectomycorrhiza are in lots of common plants like roses, orchids and Eucalypts and species are often specialised to a few plant species. The soil is full of hyphe and spores which can last quite a while after vegetation is removes. How do seedlings of plants with specialised mycorrhiza get their proper species outside their natural distribution seems a harder question to answer 

[luketrollope]

 

Nitrogen and even phosphorous  fixing through micro-organism in plants is pretty common and not unique to cacti.There are thousands of mycorrhiza species,most plants have them and they date back hundreds of millions of years. The vesicle forming types are endomycorrhiza. Ectomycorrhiza are in lots of common plants like roses, orchids and Eucalypts and species are often specialised to a few plant species. The soil is full of hyphe and spores which can last quite a while after vegetation is removes. How do seedlings of plants with specialised mycorrhiza get their proper species outside their natural distribution seems a harder question to answer 

Hi Mike thanks for that. The thing with this cactus (Pachycereus pringlei)  though is it can grow on bare rock and it's symbiotic  bacteria and fungi can break down bare rock into usable nutrients including micro nutrients. While I am aware of a lot of plants that  can fix nitrogen (did not know about phosphorus fixing plants though)  I am unaware of other plants thats symbiotic relationships (sounds kinky!) can provide all the nutrients a  plant needs for growth out of bare rock. I understand that these symbiotic relationships evolve of long periods of time but imagine with a bit of genetic engineering you could attach these microorganisms to say crop plants. Think of how much money / time and resources would be saved by not having to buy fertilizer. I imagine people have researched this topic but maybe in the future it will be possible.