corydalis seeds

[Leena]

If might share a germination success story with Corydalis hydrophillic seed:
     In 2015 I had 60 Corydalis malkensis seed from the SRGC.  (So these were dried seed from 2014.) I expected they would need warm, then cool to germinate.  That is, if I could get them to germinate.

  In late March, I took 30 seeds and placed them in a sealed small baggie with a moist (not wet) piece of paper towel, but the paper towel was not in contact with the seed.  The idea was to have the seed very slowly imbibe water from water vapor only, hopefully not destroying the cell integrity of the seed as it re-hydrates.  15 days later the seed had noticeably enlarged, and I planted them in soil.  They spent the rest of summer and winter outdoors.  The following March, 25 seedlings emerged at the 4-10C range.

Apparently, many recalcitrant seeds are not actually dead when they lose water.  But due to the loss of water, cell walls are forced to shrink, but can't do it uniformly.  Instead the rigid walls crinkle up like aluminum foil.  Normal re-hydration forces these crinkles to straighten too fast.  The integrity of the cell walls break and the cells die.  But very slow water imbibing allows cell walls to slowly straighten back to the previous shape without damage. 

Rick, that is very interesting, and it gives hope with some dry rare seeds! Your theory could explain why I have never had success with some of dry Corydalis seeds. I soak them in water overnight and it is too fast most likely.

[Rick R.]

Regarding Corydalis self-fertilization, I can say for sure that my single C. nobilis plant produces viable seed.

[Lesley Cox]

I was given recently, 2 seedlings of Corydalis heterocarpa a giant Japanese corydalis. I'm told it is perennial but in any case seeds freely and grows to 60cms or so in a coolish, humusy soil. Flowers are yellow and white with a brown spot. Mine are still smallish but do need planting out from their pots. It looks (on Google) to be magnificent. Does anyone else know it?

Re C. wilsonii - my experience is that it is biennial at best, flowering well in its second year from seed then dying and seeding (best for me, into a sand plunge). A shame it doesn't last but is lovely with its yellow flowers and almost blue foliage that it is worth growing I think.

[Véronique Macrelle]

I have Corydalis heterocarpa; it tends to be biennial here as well.
I had a magnificent plant of 60 cm in the ground, very humus. it spontaneously reseeded itself all alone the following year. a pleasure, except that a drought to a little limited the number of seeds produced: this year I do not see young plants, except a sowing in pot 2 years ago.
 where maybe winter was not strong enough to germinate the seeds.
I got it from the exchange based on dry seeds: they germinated massively after the 2nd spring. They therefore support being stored dry.

[fermi de Sousa]

I was given recently, 2 seedlings of Corydalis heterocarpa a giant Japanese corydalis. I'm told it is perennial but in any case seeds freely and grows to 60cms or so in a coolish, humusy soil. Flowers are yellow and white with a brown spot. Mine are still smallish but do need planting out from their pots. It looks (on Google) to be magnificent. Does anyone else know it?

Hi Lesley,
this was passed around in Australia as C. nobilis for a long time. In my previous garden in Boronia it swamped many smaller plants and made an effect ground-cover! It self seeded everywhere as well. I never brought it up to Redesdale but I think it probably wouldn't be as aggressive here - if at all!
cheers
fermi

[Gabriela]

If might share a germination success story with Corydalis hydrophillic seed:
     In 2015 I had 60 Corydalis malkensis seed from the SRGC.  (So these were dried seed from 2014.) I expected they would need warm, then cool to germinate.  That is, if I could get them to germinate.

  In late March, I took 30 seeds and placed them in a sealed small baggie with a moist (not wet) piece of paper towel, but the paper towel was not in contact with the seed.  The idea was to have the seed very slowly imbibe water from water vapor only, hopefully not destroying the cell integrity of the seed as it re-hydrates.  15 days later the seed had noticeably enlarged, and I planted them in soil.  They spent the rest of summer and winter outdoors.  The following March, 25 seedlings emerged at the 4-10C range.

Apparently, many recalcitrant seeds are not actually dead when they lose water.  But due to the loss of water, cell walls are forced to shrink, but can't do it uniformly.  Instead the rigid walls crinkle up like aluminum foil.  Normal re-hydration forces these crinkles to straighten too fast.  The integrity of the cell walls break and the cells die.  But very slow water imbibing allows cell walls to slowly straighten back to the previous shape without damage. 

I have also germinate C. malkensis from dry seeds Rick; only that they showed up in the second year after sowing and not in great percentage. Like in other genera (Aconitum for ex.) some species of Corydalis are more or less hydrophilic, over a large range.

Slow hydration makes sense sometime, but I cannot abstain to contradict the way you described seeds dessication. I won't start adding many links here, but very shortly - it is not a  process based on shrinking of the cell walls; the cells accumulate sugars under various forms and in certain places and usually the ratio between sucrose and non-sucrose will determine the length of viability (mostly for orthodox seeds, but maybe others too).

There would be much more to say in this regards... in any case 'rigid walls that crinkle up like aluminum foil' it is a far fetched description...
 

[Rick R.]

Gabriela, I am very glad you did not abstain!  This is how we learn, and as any open minded person knows, any theory of any kind in the natural world should always be open for review.

Of course, I was not talking about orthodox seed, rather, recalcitrant (or variations of).    Saved on my PC is
THE ECOLOGY AND PHYSIOLOGY OF VIVIPAROUS AND RECALCITRANT SEEDS, Elizabeth Farnsworth
https://www.annualreviews.org/doi/pdf/10.1146/annurev.ecolsys.31.1.107
The author also references the importance of sucrose, as you note, and also on page 114 it says:

 Loss of metabolic water during prolonged drying is accompanied frequently by fusion of vacuoles, vesiculation of the endoplasmic reticulum,and free-radical peroxidation of lipid and protein components of cell membranes, leading to eventual cellular collapse (77, 129, 132, 156).   Much of this damage is manifested during rehydration.  Both the rate of dehydration and the absolute percentage of water lost determine the extent of tissue damage sustained by desiccating embryos (40, 50, 51).

So contrary to what I previously wrote, the damage happens prior to rehydration.  (Cell walls are not metioned.)  But, the consequences still often show up during rehydration.
I distinctly recall a line drawing of such a "crinkled" cell in another paper that had solidified in my mind the dubious mechanism, although I did not (or could not) save the paper it was in.  Is it a figment of my imagination?   I defer to your knowledge. 

And upon further poking around I found this paper
https://search.proquest.com/openview/9a7e9412ddaa7e37413b204efc1bf200/1?pq-origsite=gscholar&cbl=27004
whose abstract says that slow water imbibation may actually be deleterious for some recalcitrant seeds!

Oh my!

[Gabriela]

Rick - one could read articles on seeds biology, dormancy, germination.....24/7.
Understandable, most concern species with economical value but there is a lot to learn from them anyway. Problem is, not only there is no time to do so, but also not everything it is easy to understand (unless someone knows plant anatomy, chemistry, molecular biology and everything else  in between...).
I just think that is best in general to keep it simple instead of creating more confusion.

For most Corydalis species (there is no data for all), at the time of seeds dispersal the embryos are undifferentiated (in fact just a mass of cells embedded in endosperm!), and there is so much that needs to happen in the 'right' way before we can even think about seeds treatments and germination!

[Roma]

Corydalis paczowskii sown in January 2019.  I have grown this from exchange seed before but found it short lived.