Date: Mon, 02 Feb 1998 21:55:14 -0800 From: Denis Daly <dalymob@bigpond.com> To: cp@opus.hpl.hp.com Message-Id: <aabcdefg458$foo@default> Subject: Cephalotus Seed. Is it Recalcitrant?
Dear Frank and list
I have found that Cephalotus seed need to be sown almost
immediately they are harvested in autumn. They will remain in the
pot (moist) until spring when they will germinate.
I used a batch of seeds collected from my own plants. Half were
sown immediately (in autumn and germinated the following spring)
while half were stored over winter and sown in spring. None
germinated. [2]
I believe that Cephalotus seeds are likely to be Recalcitrant.
Moist cold storage (stratification) is useless if the seeds have
dried out and died before you stratified them.
The term recalcitrant is applied to seeds that remain viable for
as little as a few days,
months, or at most a year. [1]. However recalcitrant seeds are
short lived primarily due to their
sensitivity to reduced moisture content. [1]
Recalcitrant seeds must retain a reasonably high moisture content
of around 30 to 50% if
they are to remain capable of germination. [1] The time of
viability of most recalcitrant seeds,
particularly temperate species, can be increased if the seeds are
stored moist at temperatures just above freezing. [1]
Seeds likely to be Recalcitrant:- 1) Seeds that are produced in spring
or early summer and germinate very soon after they fall to the ground.
[1] (e.g. Dionaea, Sarracenia (possibly if it's early enough in the
season), Highland Nepenthes, certain Drosera, Heliamphora.)
2) Seeds of tropical plants that grow under conditions of high
humidity and temperature. [1]
(e.g. Lowland Nepenthes, some Mexican Pinguicula, certain
Drosera.)
3) Seeds that mature in Autumn and spend the winter in moist or
even frozen soil awaiting the
spring. [1]
(e.g. Dionaea, Sarracenia, Darlingtonia, Heliamphora, Cephalotus,
certain Drosera, Utricularia, N. khasiana, US & European and some
Mexican Pinguicula)
4) Many seeds of temperate aquatic plants. [1]
(e.g. Aquatic Utricularia, Genlisea, Aldrovanda,)
While I have cited various species of carnivorous plants to fall
into the categories of natural seed storage that can lead to the
species evolving Recalcitrant seeds it should be noted that it
does not necessarily follow that the seeds are Recalcitrant. I do
not have scientific proof but I believe that the possibility that
many carnivorous plant seeds are Recalcitrant.
Note that stratification is the same as moist cold storage. What
matters is how much the seed might dry out before you put it into
stratification (moist cold storage). For details see reference 3.
References
[1] HARMANN Hudson T., KESTER Dale E. & DAVIES Fred T. JR, Plant
Propagation Principles and Practices, Prentice Hall Career and
Technology, New Jersey, Fifth Edition, 1990, ISBN 0-13-681016-0.
[2] DALY Denis, Propagation of some Specific Species of
Carnivorous Plants, FlyTrap News Vol 9 No 1,
July/August/September, 1995, The Carnivorous Plant society of NSW,
ISSN 1323-8159.
[3] DALY Denis, Storage of seeds .... are we killing them?,
FlyTrap News Vol 10 No 4, April/May/June, 1997, The Carnivorous
Plant society of NSW, ISSN 1323-8159.
Regards
Denis Daly
P.S. Food for thought?
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