Clusius seed

Jim McKenney
Thu, 08 Nov 2007 10:53:40 PST
Dear Ben, I certainly didn't intend to lecture you or anyone else on
genetics. My intention was simply to give readily understood examples so
that those without a technical background who are following these posts
might more easily understand what the possibilities are. 

Nor am I trying to deny that Clusius raised tulips from seed. The time spans
from planting to bloom which he reports are consistent with what we know
about tulips now. But those words "old and shriveled" strongly suggest to me
that his original gift from Busbeq included at least some bulbs or bulblets.

In an earlier post I suggested that the time span indicated by Clusius was
not long enough to achieve the level of diversity he reported. In response,
Ben suggested that perhaps Clusius started with a species which is by nature
variable. And he gave as examples of such species Tulipa clusiana and T.

Let's give some more consideration to those time spans. If Clusius planted
seed in 1573, then according to the timings he reports, he would have had
the first flowers in 1579 or 1580. The earliest-to-bloom of the second
generation would not have bloomed until 1586 or so. If as you say his
account was written in 1592, then he could have seen at most only three
generations from any original seed. And those would only have been the
tulips which bloomed in six years from seed. The second generation of the
eight year plants would not have bloomed until 1589 or 1590, only two years
before he wrote his book. 

I'll say it again: I think it is highly improbable that the variation which
seems to have occurred in the tulips of Clusius in only three generations at
most is not congruent with origin from a single species. 

Tulipa clusiana has been mentioned in this thread as an example of a species
of Tulipa which is variable, variable in a way which might help understand
the origin of the tulips of Clusius. Perhaps everyone is not aware of some
the ways in which this species in peculiar. It is worth noting that the sort
of variation seen in Tulipa clusiana in the very broad sense is sometimes
associated with varying chromosome counts. Populations of this species are
known to range from diploid to pentaploid. This species is also
stoloniferous. One consequence of this is that some of the so-called
populations are likely not sexually reproducing populations at all but in
effect clonal aggregates representing the successful colonization of an area
by stoloniferous growth. 

When in an earlier post I expressed doubt about various color forms being
sympatric, by "color forms" I had in mind sexually reproducing populations.
But with Tulipa clusiana one would expect populations which seem to be mixed
in color. But can they properly be said to be mixed? Are they properly to be
considered populations? Certainly if there are "populations" which have
resulted only from the stoloniferous growth of a distinct form, then these
"populations" are in effect no different than clones propagated in gardens.
Is there really any genetic exchange between the diploid forms and the
pentaploid forms? Isn't it possible that they simply exist side by side
without any active reproductive relationship among them? 

And so far we have not addressed the obvious question: if the tulips of
Clusius were derived from a species, which species might that be? Are we to
believe that his tulips were derived from a species now extinct?

So, although it is true that Tulipa clusiana provides a wealth of variation,
that variation comes with variation in chromosome count. I think that makes
it a dubious candidate for consideration as the source species of Clusius'

Tulipa schrenkii has been mentioned. Ben, do you believe that Tulipa
schrenkii is a likely ancestor of our garden tulips? My impression is that
Tulipa schrenkii so-called is not a species in the modern sense, but
probably the locally naturalized survivors of primitive garden tulip
populations. What does the most modern evidence say about this plant? 

Jim McKenney
Montgomery County, Maryland, USA, USDA zone 7 where it finally got cold
enough to collapse the garden impatiens. 

My Virtual Maryland Garden

Webmaster Potomac Valley Chapter, NARGS 
Editor PVC Bulletin 
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