Erythronium germination

[Diane Whitehead]

Erythroniums grow in many places in the Northern Hemisphere, and require
different circumstances to germinate. There are two basic groups: those
attractive to ants, and those not. 
http://www.ou.edu/cas/botany-micro/ben/ben356.html  describes experiments
by an amateur gardener.   Erythroniums from Japan, Europe, and Eastern
North America have elaisomes which attract ants. Those from Western North
America don't.  Ian has explained in his logs how he sows seeds of these two
groups at different depths.

I have just discovered a paper, Ecophysiology of seed germination in Erythronium
japonicum (Liliaceae) with underdeveloped embryos
   http://www.amjbot.org/cgi/content/full/89/11/1779
by Tetsuya Kondo, Nori Okubo, Taku Miura, Kazushige Honda and Yukio Ishikawa.

They tested many variables and combinations of variables -  constant,
alternating or variable temperatures, light.
They had many lab experiments, and also outdoor pot experiments.They didn't
just observe the outside of the seeds, but also sliced them open to see what
was happening to the embryos.

They found that Erythronium japonicum seeds are not able to germinate as soon
as they are shed, because the embryos are immature.  They require a hot period
for the embryo to lengthen, then a cooling period for germination. Seeds would
germinate if given 90 days at 25C, then 5C, or if they were kept around 10C
(or 15C days/5C nights).  They did not germinate if kept at these temperatures:
0°, 5°, 15°, 20° or 20° days/10°C nights .

 In nature, the seeds have germinated by November, and seedlings emerge
as the snow melts in spring.

There are other species that also have immature embryos, E. albidum, E. grandiflorum,
E. americanum, and E. rostratum.  Their temperature requirements differ, and
their embryo elongation is either later, or carries on later (closer reading of the
article needed here.)

The bibliography lists papers on germination of these Eastern U.S. species.

[Maggi Young]

Excellent information, Diane. Thank you, I need hardly tell you that Ian the Bulb Despot is delighted to have you begin this thread on his favourite plants!  Some of the links you give are new to us so we will be reading them carefully.

[Diane Whitehead]

I have discouraging information on the viability of wild-collected Erythronium seeds.

I have just dumped out all my ungerminated seeds to see how many remain, and the answer is often "not many".

A friend gave me many, perhaps more than a hundred wild E. revolutum seeds.  He had collected them in the summer of 2003 and gave them to me in late spring 2004.  As they germinated, I removed them and planted them in pots.  There were still the majority of the seeds in the bag of peat-based mix, but when I picked through it today, I found dozens of empty seedcases and no intact seeds.

I then examined wild-collected seeds I had bought from Ron Ratko. The seed had been collected in 2002 and 2003, and I bought it in spring 2004.  Two species have had some germination, but four have had none, and today I found no intact seeds.  The packets had contained a lot of seeds:  57 pusateri, 85 pluriflorum.

When seedexes include only about five seeds per packet, what chance is there of actually getting a bulb?

The only ungerminated seedex seeds that are still plump are the eight E. quinaultense that Art Guppy sent to the AGS in 2005.  They haven't germinated yet, but all eight are still good.  Art is the person who lives just north of me in Duncan, in the Cowichan Valley.  He has experimented with Erythronium for about 30 years, and wrote the article I mentioned in my first post.  I must write him and see how he treated his seeds prior to sending them to the AGS.  The AGS seeds always arrive first, and these ones were sown early in January.  All the others that disappeared were not received till later, and therefore were sown in April and May.  Could that have helped them fade away?

Now, I am just mentioning the failures.  There have been successes, but I am really surprised at how few wild seeds germinate.

[Gene Mirro]

I never place newly sown seed directly into cold conditions.  My reasoning is that the seed needs to absorb water before the germination "clock" can start.  It is very difficult for the seed to absorb cold water, because of high surface tension.  It is much easier for the seed to absorb warm water, and this is what happens in nature.  The seed is dispersed in mid-summer, gets moistened by the fall rains, and germinates in spring.  After planting the seeds in moist mix, I place the pots in sealed plastic bags, and keep them at around 20C for several weeks, and then place them in the fridge or the cold greenhouse.  Germination percentage is very high.   I use this technique on all seed which requires winter chilling, not just Erythronium.  The only evidence that I can offer is that this technique is very successful for me, and all the other techniques which I have tried are much less successful.  And believe me, I have tried all of the unsuccessful techniques.

In Ian's bulb log, he mentions soaking the seeds before sowing.  This does the same thing, assuming that they are soaked in warm water.

Diane, about the seed which is sown in spring, my theory is that the warm temperatures of the growing season cause the seed to metabolize its stored food reserves for a full year, while it is waiting for proper germination conditions.  A warm, wet seed is not inert; it needs a source of energy.  By the time a year goes by, the poor seeds are too weakened to survive, or to make sturdy seedlings.  When I get seeds at the wrong season for sowing, I place them in airtight containers and put them into the freezer at 0F.  They will last indefinitely.  This only works for seeds that can be thoroughly dried before freezing.

[Diane Whitehead]

That makes sense, Gene.  I definitely need to change my technique.  What I have had the most success with is just tossing the seeds around as soon as they are ripe, but I can only do that with seeds from my own garden or ones I collect.

I know Ron Ratko had some of his seeds in damp vermiculite in ziplocks once when he was selling seeds at a Western Winter Study Weekend, but I can't remember for sure whether that was the case with the Erythronium seeds. 

[Ian Y]

Fascinating information here from Diane and Gene.

Gene I do soak my seeds in slightly warm water and the soaking seeds remain in our house while they are soaking so they do have at least 24 hours in warm conditions before being placed outside.

The best germination results that I get are from my own garden collected erythronium seeds. As I have explained in the bulb log I store them in paper bags in a shed through the summer then soak them before I sow them around September.

Reading Gene's explanation above and the information on the links supplied by Diane I discover I have stumbled upon a similar strategy allowing a warming period for the embryo to extend before a cold period after I sow them and leave the outside for the winter.

I also get what appears like a good germination from the ones that I am letting naturalise at the top of the garden. However when I consider just how many seeds must be shed in that bed the germination rate is very low.

This takes me back to what I was saying in this weeks log regarding our high expectation of the percentage of seeds that will germinate in the first year compared to what actually happens in the wild -sporadic germination.
Some seeds may lie for several years until the conditions trigger germination while others from the same capsule may germinate immediately. The range of germination times in the wild will vary according to the slight variation in the genetic make up of the seed and or the differing micro climates of the spot the seeds were shed into, or in the case of E. japonicum where the ant may have  taken it.

I have also experienced a total failure of germination from some wild collected seeds but luckily I have managed to get some seeds from most of the species to germinate and go on to set good seed in our garden where I have more control.

[Jim_in_mi]

As I recall from one of my Hort classes long ago at "University", seeds sown in cold conditions may experience imbibition injury.  Ever since then I always let the pots stay at room temp, or warmer, for a period of time (usually a week) before they go into the fridge or outside.  Seed is designed specifically to move water into the interior, and some proteins can apparently be damaged in cold temps while absorbing water, if I recall correctly. 
Jim

[Maggi Young]

Diane, Jim, lovely to SEE you now, with your ID pix!
I think this thread shows us, again, that getting fresh seed, or storing seed in careful conditions is so important. While the occasional species seems willing to germinater, no matter what, all too often there is a limit to what the gardener can do to remedy the state of old or damaged seed.
Thank goodness none of that stops us trying, though! I would say to anyone new to this "game", don't be put off, thinking that there are nothing but difficulties in growing from seed -- try it, you may have the magic touch and be a natural!!