Agave virginica

Tony Avent tony@plantdelights.com
Mon, 08 Jun 2009 18:40:00 PDT
Jim:

I'm reminded of a story a couple of years ago, when a visiting European 
taxonomist/Nomenclature Code author and another arisaema expert were 
visiting. I asked them about arisaema hybrids, causing them to laugh. 
When I explained that we had crossed two species from the opposite ends 
of the arisaema family tree, the laughter became louder. Once I showed 
them the photo of the hybrid in flower, anger took over for the 
laughter....their apple cart had been upset.

Another thought...what happens when you cross a tuber (polianthes) with 
a non tuber (agave or manfreda)? Does it become a tuberous root or 
perhaps we should create a new term such as an xtuber.


Tony Avent
Plant Delights Nursery @
Juniper Level Botanic Garden
9241 Sauls Road
Raleigh, North Carolina  27603  USA
Minimum Winter Temps 0-5 F
Maximum Summer Temps 95-105F
USDA Hardiness Zone 7b
email tony@plantdelights.com
website  http://www.plantdelights.com/
phone 919 772-4794
fax  919 772-4752
"I consider every plant hardy until I have killed it myself...at least three times" - Avent



Jim McKenney wrote:
> Several things in Tony’s post deserve comment. It always fascinates me to
> see how different people come to very different conclusions even when they
> seem to start with the same basic assumptions. 
>
>  
>
> First, I would like to raise the touchy subject of just what this word
> monocarpic means. I’ve always understood the word to mean that the plant so
> described dies after blooming and setting seed. Yet many of the plants
> called monocarpic by some people do not die after blooming and setting seed.
> The main rosette of such plants dies, but by then the plant has often
> offsets  and is surrounded by offsets which perpetuate the plant. 
>
>  
>
> To me, the pup and the main plant are the same plant, pieces of one original
> seedling. If you are the sort of person who regards the pup and the main
> plant to be different plants, they you’ve got your argument cut out for you.
>
>
>  
>
> The use of this word monocarpic– whatever you think it means -  with respect
> to Agave is particularly appropriate because the nineteenth century botanist
> de Candolle who coined the word  used Agave as an example. As a result,
> there are those who take the point of view that by definition it is correct
> to call Agave monocarpic no matter what you think the word means. To these
> people, that fact that the etymology of the word seems to be saying
> something about Agave which is not necessarily true is irrelevant. 
>
>  
>
> As a result of all of this, many people now eschew the word monocarpic
> because of the ambiguities surrounding its meaning. 
>
>  
>
> Now on to this business of the significance of hybridization to taxonomy.
> Here again, where you end up in this discussion depends on where you start.
> To state the argument in one of its most radical forms, there are those who
> would say that the ability of two plants to cross and produce viable
> offspring is evidence that they are conspecific, they are the same species
> (never mind Tony’s concern about its significance at the generic level. I’m
> talking about the species level).  To those who adopt this approach, what
> the plants in question look like has nothing to do with it. 
>
>  
>
> One of the unresolved questions which taxonomists have to deal with is the
> nature of the ranks/categories they use. There are two basic schools of
> thought on this matter. One school asserts that species is a real, natural
> phenomenon – that there really is something out there which corresponds to
> what we call species. The other school of thought says that species is
> whatever we decide it is. I’ve never seen a plausible argument from either
> side in defense of the “natural” nature of genera – I think that the
> consensus on both sides is that  genera are man made.  
>
>  
>
> The “natural species” point of view will be robustly rejected by those who
> expect taxonomy to have some practical value in pigeonholing items. 
>
>  
>
> One result of this huge dichotomy in what people think is the proper
> function of taxonomy is that parallel systems of naming coexist side by
> side. To give a simple example of this, the wild typical form of Narcissus
> jonquilla is known to botanists as Narcissus jonquilla (or if you prefer N.
> jonquilla subspecies jonquilla). Yet in the horticultural literature, this
> same plant is known – and has been known for centuries - as Narcissus
> jonquilla simplex. Horticulturists like this name because it expresses what
> is important to them – it distinguishes the single- flowered form (single in
> the sense of normal flowered, not one flowered) from the various
> double-flowered forms (those forms in which the floral parts are deformed
> and multiplied). Horticulturists are concerned about a distinction which
> does not even register on modern botanists’ radar. 
>
>  
>
> Finally, those plants which result from the fusion of alien genomes really
> don’t enter into taxonomic discussions of the sort which are based on
> traditional assumptions about shared ancestry. 
>
>  
>
> So when Tony says “Wait until they see the new x Velox...a cross of Verbena
> and Phlox (reportedly a result of protoplast fusion)....we're talking
> different families. That should turn the taxonomists on their heads.” he
> might be right about it turning them on their heads, but if it does I’ll bet
> that the turning of their heads will be the result of their being bent over
> in laughter.  The little × in front of that name Velox (is there really such
> a thing?) identifies that name as a nothotaxon - it tells you that it is
> from a naming system which is distinct from the naming system used in
> traditional botany. The feelings of traditional taxonomists  might very well
> be more on the order of the feelings – not nice feelings, but undeniably
> funny – you get when you visit the shabby side of town and see – well, you
> see the sort of things which go on there. 
>
>  
>
>  
>
> Jim McKenney
>
> jimmckenney@jimmckenney.com
>
> Montgomery County, Maryland, USA, 39.03871º North, 77.09829º West, USDA zone
> 7
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