Cosmos atrosanguineus

Roger, I have grown this plant for more than ten years in what was
originally Climate Zone 9 (and is now 10) in Pebble Beach, CA, about 1000
yards from the ocean at about 150' elevation. It gets no special care in a
perennial flower bed and has now increased to 2 plants. No seed, though I
kept looking for a number of years. It even survived a gardener pulling it
up as a weed, though, of course, he didn't get much of the underground
structure. My characterization of it would be that it is fairly tough and
not all that rare, and most people think of it as a perennial and not a
tuber.

Shirley Meneice

-----Original Message-----
From: pbs-bounces@lists.ibiblio.org [mailto:pbs-bounces@lists.ibiblio.org]
On Behalf Of Rodger Whitlock
Sent: Sunday, September 16, 2012 12:38 PM
To: Pacific Bulb Society
Subject: Re: [pbs] Cosmos atrosanguineus

On 16 Sep 2012, at 9:25, James Waddick wrote:

I am sure regular readers of this forum and of the wiki are
aware of the odd history of this tuberous species. See
http://pacificbulbsociety.org/pbswiki/index.php/…

The plant was originally collected in Mexico, then believed
to have become extinct. All cultivated plants are a single clone
propagated by micro-propagation or division of its Dahlia-like
tubers. The plant is sterile and produces no seed.

It appears almost certain that more than one clone has been in cultivation,
contrary to the received truth. New commercial clones have been coming out
of
NZ, Japan, and possibly the Netherlands. I have one, 'Chocamocha',
distributed
in Canada (and, I suppose, the US) by the Proven Winners people.

This development, it seems to me, would not have come about had only one
clone
been in cultivation. A possible wrinkle is that within the last few years,
the
plant has been rediscovered in the wild, in Jalisco, Mexico, and seed
gathered.
My understanding is that that seed went to the Rancho Santa Ana Botanic
Garden,
but there's no telling just how widely it was thence spread.

The archive of this mailing list has some older discussion worth reviewing.

A few years ago a fertile seed strain was 'discovered' in
New Zealand and has slowly entered cultivation. Seedlings can be
crossed with the established clone to produce fertile seed and at
least a couple of new cultivars have been developed.

According to a member of the SRGC who kindly sent me a few seeds two years
ago,
the issue is that the plant is self-sterile and the usual commercial clone
sets
very little pollen. However, at least two SRGC members have obtained viable
seed from their own specimens.

By an odd coincidence I was recently given a small quantity
of seed of this still very rare plant. Of course, having never grown
it from seed, I'd appreciate any guidance from any of this group's
members who may have grown this species from seed or some
suggestions on how best to succeed.

Here's what I did: Seed arrived in 2010. I held it over winter and sowed it
in
spring 2011 in a 4" square pot. Generally speaking seed of the Asteraceae,
if
sown in fall or winter, tends to simply rot. I don't remember how long it
took
for seedlings to emerge once sown, but it wasn't very long.

When the seedlings had formed true leaves and were actively growing, I
potted
them on together into a 150mm high x 115mm square pot. Later in summer 2011,

they were again potted on into a single pot 210mm x 210mm.

In fall 2011, I put the pot into my carport (along with my pots of
commercial
clones) and allowed it to dry out. When colder weather approached, it went
into
cold, but frost-free, storage for the winter, bone dry, but the tubers still

potted in soil. In spring 2012, once the threat of serious freezes was past
(say, in March), the pot was brought out again into the carport, but water
was
withheld until active growth started. In this regard, the plant is similar
to
the Japanese woodlander, Pinellia cordata 'Yamazaki': no water until you
start
to see leaves emerging and even then only small amounts until you have
active
growth. Weldenia candida, another Mexican mountain plant is also best
handled
this way.

My seedlings has been potted on twice this year. They are currently in a pot

300mm high and 280mm diameter, and are flowering to beat the band. The
seedlings produce reasonable amounts of pollen. Applyied by hand to flowers
of
the usual commercial clone, I am getting significant amounts of seed: say,
between ten and twenty seeds per flower. The back cross (commercial clone
pollen on seedling flowers) is not as productive, but there is some seed
forming from it.

Using seedling pollen on 'Chocamocha' is producing lesser amounts of seed.

It is quite clear that the chocolate cosmos enjoys plenty of root room and
lots
of water during its period of active growth in summer.

It is still too rare to mess up.

In my books, it is no longer a rare plant and hasn't been for a good ten or
fifteen years since the commercial was cleaned of viruses and widely
propagated. As the generous donor of seed to me put it, nurserymen like it
because it usually dies and has to be replaced annually. It's sold here in
4"
pots for about $5 a pop.

What remains rare is seed. Some of you may be tempted to write me asking for

some, but please don't if you aren't familiar with this plant and don't have

the time and patience to bring seedlings to flower and produce seed on your
own. My private goal (method of attainment as yet uncertain!) is to convert
this plant to one which is widely grown from seed by those with the
necessary
interest. Otherwise, in not too many years, we may be back to having only a
single, sterile, virus-laden clone that challenges even the best growers to
keep alive.

--
Rodger Whitlock
Victoria, British Columbia, Canada
Z. 7-8, cool Mediterranean climate