Squash-like plant, vines form secondary root systems?

[Spinnor]

We have some type of squash plant growing in a small garden. It remarkable how much it has spread. I would think it advantageous for such a plant to form additional root systems, try as I might I do not see them on this plant. Is that typical of squash and pumpkin type plants, no additional root systems? Seems with parts of the plant quite a distance from the original roots that it would make evolutionary sense for the vines to put new roots down from time to time as it grows along the ground?

Thanks for any help!

 

[jim mcnamara]

Do not try to out-dumb evolution. You will get a headache. Why questions often have a single answer in evolutionary context.: because.

We cannot work backwards in a time warp and see why some plants did X while others did Z.

Good question, though!

Adventitious roots ( what you are talking about) are great to get additional "grab" on a substrate like a rock or a twig. Tendrils are modified leaves that answer that same problem. Most domesticated and wild squashes may have small tendrils, and usually no adventitious roots. Why?

Next issues - squashes are a taxonomic disaster zone. There are several species of Cucurbita that humans have interbred, and generally messed around with forever, almost, likely since the end of the last glaciation ~10000ya, Cucurbita pepo is the modern name for all this mishmash, it is a "lumping ground" because the floral structures have remained unchanged. Everything else is all over the map.

Discussion: http://cuke.hort.ncsu.edu/cgc/cgc10/cgc10-36.html talks cucurbit biological pathways based on enzyme samples for North and South America. C pepo is best called a human derived species IMO.

So you may have a stink melon and not a squash. Wild cucurbits all taste uniformly horrible. Some domesticated ones are not meant for eating and also taste equally bad. It won't kill you to try it - cooked well done - to see if it is possible to eat. Have a spit-it-out bowl ready.

Bottom line: I don't know why and I don't know anyone who is self-confident enough to say anything other than 'I do not know'

 

[Spinnor]

Will take a picture when light, I think the wife cooks and eats them.

 

[BillTre]

I saw some article on these plants recently but could not find it.
I find cross-hybridizations interesting. Are they different levels of polyploid?

More why questions for you Jim:
My understanding is that big fruits are often an aid to the plant in that something eats them which results in the seeds being more widely distributed.
So what's with the bad tasting fruits?
Is that just human taste?
Does the uneaten fruit act as a fertilizer?

 

[Spinnor]

So could the answer to my question be that vine type plants in the wild grew up things so that their vines would normally not be near the ground?

Thanks!

 

[jim mcnamara]

Fruits act to facilitate seed distribution - you have probably heard of the so-called 'constipated bird theory' of seed distribution.

Example: Arceuthobium spp, mistletoes that infects pines and cedars in N America, have small white fruits that contain a single seed. The seed has to pass through a bird's digestive tract before it will germinate. Digestion also activates a sticky, gummy resin on the seed surface that holds the defecated seed in place - if it is lucky enough to have been dropped on a susceptible gymnosperm tree.

Bitterness (Saponin) is a sort of a biochemical byproduct that usually relates to "pest control". In the case of squash - e.g., winter squash - that do not have physical damage from bugs or fungi, will dry and form a harder ball, which acts as a seed time capsule. You can do this at home - wash a blemish free acorn squash in a borax solution - in the US '20 Mule Team Borax' is available. This kills off any surface fungal spores. The hardball squash will last for years. This is the same idea with gourds which are the easiest curcurbit to dry and turn into a hard ball. No borax needed in the wild.

The "reason" for the time capsule thing - wild squash require seed stratification(cold period) to germinate.

Since the seeds do not survive animal digestive tracts, and need to get cold exposure, a time capsule is good safe long term storage. Bare seeds on the surface are more likely to be eaten. Alternatively, an animal like a ground squirrel can bury the seed, also good. Either way, the seed is kept safe during the cold season, and survives until once again gets some warmth and moisture. So if vertebrates stomp the dried capsules -> voila, more squash plants. Getting buried seeds to the surface is a lot more iffy. So. Some seeds will germinate as deep as 12 cm - see link below.

This is a very interesting link about stinky melons which are roadside plants here in New Mexico. My neighbors on the reservation made rattles, bowls, and soap from them:
https://en.wikipedia.org/wiki/Cucurbita_foetidissima

Since most curcurbit seeds need a dormant cool period the fruits themselves do not provide nutrition, only "pesticides" and allelochemical compounds.
https://en.wikipedia.org/wiki/Allelopathy

"pesticide" concept related to allelopathy:
https://en.wikipedia.org/wiki/Plant_defense_against_herbivory

@BillTre - that should give you what you need to get an idea about plant reproductive strategies. The word strategy may imply cognition, but in this context there is none. Plants do not think. Period.

 

[jim mcnamara]

@Spinnor - those look like pumpkin sports to me. A sport is a descendant of a domesticated species on its way to reverting to more locally well-adapted wild traits. This happens a lot in cultivated fields. Another term used is an escape variety - the plant has escaped captivity I guess is the meaning.

Most pumpkins' parentage is Cucurbita maxima. https://en.wikipedia.org/wiki/Cucurbita_maxima. This is part of the taxonomy mess I talked about - Economic Botany is full of problems like this, best suited to DNA analysis. Humans have messed with, experimented on, and practiced selective breeding on plants for the last 8-10 thousand years.

And. For all kinds of purposes and end results - C maxima is now bred for diverse uses: pies, punkin chunkin, jack'o'lanterns, and animal food. To name a few.
[nonsense]
Here is a real first world "sport" for you, punkin chunkin it is called around here. People here do not seem to be able to say pumpkin, for reasons I don't get.

http://alibi.com/events/167620/20th-Annual-Punkin-Chunkin.html

There is a farmer in Moriarty NM that has bred and sells really hard, dense, symmetrical "pumpkins" for ballistic use. Go figure. He started with sugar (pie) pumpkins and crossed them with some kind of gourd. I think. I am told those things get shot for large distances. Resisting internal and external ballistic forces is a major problem since the pumpkin has to hit the ground still in pumpkin form to count as valid in the contest. It does not survive impact.
[/nonsense]

 

[jim mcnamara]

@Spinnor

So could the answer to my question be that vine type plants in the wild grew up things so that their vines would normally not be near the ground?

Probably not - if you read the articles I cited earlier and follow the links in the C pepo or some of the links in the pumpkin article, there are pictures of ancestors.
Most cucurbits require full sun. All of the curcurbits I have seen grow well in open spaces and on the ground. The domesticated ones can be coerced into hanging on a fence or whatever. The wild ones I saw in South America were all ground dwellers at higher altitude, well above dense forest - called the Altiplano.
https://en.wikipedia.org/wiki/Altiplano.

This link (also above) shows what I mean, the plants are primarily adapted as ground dwelling full-sun species, tree climbing means partial shade.
https://en.wikipedia.org/wiki/Cucurbita_foetidissima

 

[Spinnor]

Fruits act to facilitate seed distribution. ...

Biology is so complex and interesting, thank you Jim!

 

[BillTre]

Very informative @jim mcnamara! Fun stuff.
You are a font of botanical information.

 

[Hairry]

FWIW...

I've grown squashes and relatives several times; in my garden all seem to form adventitious roots along the vine. I bet if a segment of the vine was covered (with soil, or even in a bag containing like sphagnum moss and water- dark and moist are the triggers) you'd get those roots. And yes, squashes are hybrids, often of several species. Systematics is not real helpful but I several curcurbit genomes have been sequenced.
https://link.springer.com/chapter/10.1007/7397_2017_1

ciao!

 

[Spinnor]

FWIW...

I've grown squashes and relatives several times; in my garden all seem to form adventitious roots along the vine. I bet if a segment of the vine was covered (with soil, or even in a bag containing like sphagnum moss and water- dark and moist are the triggers) you'd get those roots. And yes, squashes are hybrids, often of several species. Systematics is not real helpful but I several curcurbit genomes have been sequenced.
https://link.springer.com/chapter/10.1007/7397_2017_1

ciao!

I will take a closer look for adventitious roots!

 

[jim mcnamara]

@Hairry - yep squashes are a mess just like corn, wheat, and other crop plants. This is no surprise - we select plants that do not have germination requirements, are fairly uniform in lots of traits, and are derived from all manner of other plants. DNA can help to sort out plant lineages, so can elementary Biochemistry.

The article I posted shows biochemical data which is an acceptable proxy for DNA when you work in state university Agriculture labs, i.e., underfunded.
http://cuke.hort.ncsu.edu/cgc/cgc10/cgc10-36.html.
Things like polyphenols, saponins and so on are mostly derived from the ancestral species.
http://cuke.hort.ncsu.edu/cgc/cgc10/cgc10-36.html

 

[NascentOxygen]

The trailing pumpkins I see growing do put down clumps of wispy roots out along the stems, but they seem more designed for stability (so that the big top-heavy leaves are kept upright and directed towards the sky) than for extracting extra nutrients. Without these anchor points, in blustery conditions the trailing stems could all end up blowing back and forth and becoming a tight tangle, unfit for collecting much sunlight or rain. Though I have noticed, on a hot day if I lift up one of the long stems out of the soil for a few metres to relocate it out of the way, the leaves on the uprooted vine will soon show some wilting, I guess this confirms the secondary roots must be involved in collecting moisture from the soil.

 

[Spinnor]

I guess this confirms the secondary roots must be involved in collecting moisture from the soil.

I've grown squashes and relatives several times; in my garden all seem to form adventitious roots along the vine.

Could that be an advantageous root system? Give a gentle pull.

If you can't find what you are looking for, keep looking.

 

[NascentOxygen]

It would be an interesting experiment to neatly sever one of the stems from a healthy vine that's nearing maturity, to see whether the small roots if left undisturbed along the stem will develop into a strong root system sufficient to support the vine into sustained fruit production.

 

[jim mcnamara]

Interesting pumpkin "geneology" -
https://phys.org/news/2017-10-pumpkin-genomes-sequenced-revealing-uncommon.html

 

[Spinnor]

Interesting pumpkin "geneology" -
https://phys.org/news/2017-10-pumpkin-genomes-sequenced-revealing-uncommon.html

This is a good time to study Biology or not!?

In another universe I would hope I studied Biology, had smaller feet and was a bit taller.

 

[Spinnor]

It would be an interesting experiment to neatly sever one of the stems from a healthy vine that's nearing maturity, to see whether the small roots if left undisturbed along the stem will develop into a strong root system sufficient to support the vine into sustained fruit production.

Might try that next year when the wife isn't looking at her pumpkin plant.

 

[BillTre]

This is a good time to study Biology or not!?

I would say yes!

Watson and Crick described the structure of DNA in 1953.
Since then biology has been getting continuously more interesting, at an increasing rate.
Modern molecular genetics/biology, combined with traditional methods while using computers to critically analyze huge amounts of data (not just sequences) has lead to a golden age in the understanding of biology.

 

[Hairry]

It would be an interesting experiment to neatly sever one of the stems from a healthy vine that's nearing maturity, to see whether the small roots if left undisturbed along the stem will develop into a strong root system sufficient to support the vine into sustained fruit production.

This very thing happens annually in my garden. Each year my thick stemmed/large leaved curcurbits are victims of squash vine borer caterpillars. Their eggs are laid on the underside of the leaves, the babies crawl onto a petiole, and dig in... petioles are hollow, so they crawl to and start eating the central, solid vine, typically near the soil end. As these eat and grow into full-sized (>1 inch) caterpillars, the vines are eaten from the inside out, leaving the outer wall hollowed out, the leaves severed from the original roots, and damaged tissue succumbs to (limited) secondary bacterial/oomycete/fungal attack. If secondary roots get established, the plant survives.

The lazy/organic answer is to heap soil over the vine so adventitious roots take over as the stem is physically separated from the roots, allowing continued growth and harvest of fruits (I usually grow "summer squash"...in my case pattipans and/or yellow zucchini; I avoid "crookneck" types as flavorless). I currently have one "bush type" (i.e., very short vine) plant that has easily 2 feet of dead vine at the original root end, and 3 feet of living vine with lots of roots; it is a F2 plant originating from the variety "Sebring". Tasty, but not terribly prolific this year.

Cukes seem to be immune to the borer- maybe their stems are too small (~0.5-1 cm diameter vs. 2-3 cm diameter for the squash above).

The moth itself is fascinating- the adults very strongly resemble big nasty wasps in appearance and behavior. Nice camouflage. They pupate in the soil- I find them annually.

Happy halloween!