Re: Propagation/Germination
- Subject: Re: Propagation/Germination
- From: T* &* M* R*
- Date: Thu, 19 Jul 2001 16:16:33 +1200
William Glover wrote:
always exercise patience with seeds. While
> > visiting the Nairobi
> > Arboretum in December 1999 I collected a number of
> > seeds - the size of an
> > English walnut - of Castrospermum australae (Moreton
> > Bay Chestnut) .. one of the seeds I kept germinated a few
> > weeks ago a year and a half after it was potted up. This is the record
> > for slow germination to date, but I am still of hope that one if not both of
> > the two seeds - weighing more than 25 pounds each - of Lodoicea
> > maldivica, the celebrated Coco de Mer (or Double Coconut) brought
> > back from Praslin Island in the Seychelles and planted in the ground
> > here early last year will germinate before this year is up. The coco de
> > mer is a slow learner in every respect and viable seeds can take two years
> > to germinate.
Hi William (or are you known as Bill?)
Your mention of the Nairobi Arboretum gave me a strong dose of
nostalgia. As a Nairobi schoolchild in the early 1940s the Arboretum was
a useful resource for our botany lessons. Oddly there are only two items
I really remember clearly - a Norfolk Island Pine (Araucaria
heterophylla) and a tub filled with the Sensitive Plant (Mimosa pudica)
which we kids delighted in "teasing". No surprise I recall the Mimosa,
but why that particular tree is a total mystery! I am glad to hear the
Arboretum has actually survived. So much has gone there, I though it
might have been cut for firewood by now!
In fact, since living in NZ, I have only once more seen the Sensitive
plant but the Norfolk pine has become a real part of my day-to day
landscape, as it is widely planted around Wellington Harbour and the
seaside suburbs of my district - not very far at all from its native
island. It is a real seaside species, often in nature coming up in beach
sand like a coconut.. Nairobi must be the most inland place it has ever
grown, just a sad exile perhaps..
I wonder if you will have success with the Coco de Mer. I have the
impression it is a real relict species and very hard to establish
outside its natural home. I remember the Nairobi museum had a couple of
the amazing nuts. Tony has had the luck to once visit the Seychelles and
see it growing, which I never have.
I am not very familar with how long seeds take to germinate once
planted, but I have seen a good deal of data on longevity of stored
seeds. In general I believe the legumes are among the most long-lasting.
I recall there ws a herbarium (I think is France) which had the
misfortune to be set on fire during the Second World War. The
conflagration ws successfully extinguished, but much of the collection
was doused with water. When botanists endeavoured to dry out the
herbarium pages they were astonished to find the moisture had germinated
a lot of old legume specimens, many having been held in the collection
for more than 100 years. it is rare to find such old seeds with a
documented date and I gather some time was spent on seeking sheets which
held legumes but had not been wetted and trying out their seeds too. I
forget the final winner, but I think it could have been as old as 200
years.
Non-botanists may be interested to know why the legumes should behave
like this. It is because of a very effective survival mechanism in many
of their species which ensures a proportion of the seeds produced each
season have unusually thick coats which initially resist entry by air or
water ("hard" seeds). After a number of years the coats gradually soften
until finally they become permeable and germination can occur. In the
wild it can be a great protection against long years of drought, but may
be nuisence to growers who prefer all the seeds of a crop like clover to
grerminate simultaneously and ways have been found, by abrasion or acids
for instance, to break through the coat and release the seed without
waiting for nature.
Apart from having an impermeable overcoat other conditions which keep
air from seeds may prolong dormancy. Seeds of the lotus which were
buried deep in the anaerobic mud of a pond in (If I remember correctly)
Korea germinated after an estimated 500 years.
Claims have been made for wheat from Egyptian tombs having germinated
and grown when planted. However unless the embryo is somehow kept from
obtaining oxygen even a really dry atmosphere will not prevent it
respiring enough to gradually exhaust its food resources and death will
come after a few years. In fact any grain they have found has simply
turned to a sort of charcoal, as the air has slowly burned away its
life, and there is no way it could be grown.
Now if they had got round to sealing it in a vacuum flask!...
Moira
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, New Zealand, SW Pacific. 12 hours ahead of Greenwich Time
