Germination and genus

Jane McGary janemcgary@earthlink.net
Thu, 05 Feb 2015 10:34:40 PST
I've remarked before on the simultaneous germination of Colchicum 
seeds, even those planted in several years, apparently in response to 
a certain temperature sequence in winter. This year I had the 
opportunity to grow about 500 kinds of seed distributed from a seed 
bank that had been kept since the early 1990s by an individual who is 
now disabled. I volunteered to "take on" various genera -- whatever 
bulbs I could request, but also a number of dicots popular with 
alpine gardeners -- so I now have the chance to observe germination 
patterns in those. It is quite a surprise to see some of these very 
old seeds still viable.

Today two Leucocoryne species (South American Iridaceae) appeared, 
the first of the geophytes to do so; one is Leucoryne vittata, a 
beautiful plant I've never seen in nature (the seed bank held many 
collections of John Watson and Anita FLores, some of which I passed 
on to a friend who is expert in growing Andean alpines). It was no 
surprise that the first flushes of germination were in Dianthus and 
Alyssum, which I knew were immediate germinators, and other members 
of the Caryophyllaceae (Arenaria, Minuartia) and Apiaceae (crucifers 
such as Draba and Erysimum) appeared quickly. How amazing that the 
tiny seeds of alpine Draba or small Calceolaria spp. could survive as 
long as 20 years in cold storage! Some other surprises were several 
Eriogonum (likely to have long viability given that many are adapted 
to arid environments) and the showy South American composite 
Pachylaena atriplicifolia (I would not have expected survival of a composite).

I think at least some seeds are "timed" to germinate when the mature 
plant would normally begin to make its annual growth. Seeing how this 
timing is synchronized widely in a genus is very interesting. You may 
wonder how this would work for the immediate germinators that live in 
cold-winter areas. From what I've seen, some of them retain the seeds 
on the plant in the capsules until snowmelt and warming temperatures 
arrive. However, when I lived near Fairbanks, Alaska, an extreme 
climate, I saw that some native alpines I sowed germinated 
immediately and then remained under the snow as tiny seedlings until 
spring. Snow is a good insulator when there are no thaws for the whole winter.

I don't grow any tropical or subtropical plants since I have no 
frost-free facility here. Do their seeds tend to germinate 
immediately? Is the pattern similar throughout a genus, as it is in 
temperate genera?

About 20 people are growing these seed bank seeds, and we plan to 
distribute individual plants when they're ready through NARGS events 
and a couple of nurseries that are involved. There were more than 
6,000 packets involved, and PBS member Claire Cockcroft handled the 
distribution, a huge task.

Jane McGary
Portland, Oregon, USA




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