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Post by Alexis on Oct 18, 2007 17:45:21 GMT
True, but burkii flowers are distinctive. There should be a few ssp. purpurea and ssp. venosa (not burkii) flowers on Google. I don't know if I've got any flower photos from my own cultivated plants I could post.
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Post by Dave Evans on Oct 18, 2007 23:28:59 GMT
Yeah I agree about there being some photos of S. purpurea venosa, but I also saw so many very oddly colored flower too, regardless of the possible species. I think some of the photos are extremely low quality and the colors have actually become different from their true-life color. Many older models of digital cameras have trouble correctly recording colors that are red and purple-ish.
S. rosea flowers seem to show the largest amount of diversity in coloration, from pale cream (nearly white) through deep pink and even lilac. Colors often seen on the flowers of species of Pinguicula.
The main difference I've seen in coloration is the S. purpurea purpurea nearly always tend toward deep purple and also can develop a bronze tint to the whole plant. I've seen much less of the bronze tinting in S. purpurea venosa, but it still shows up here and there.
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Post by Alexis on Oct 19, 2007 23:00:35 GMT
Exactly. You've nailed my point on the head there.
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kath
Full Member
Posts: 79
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Post by kath on Feb 27, 2008 4:00:14 GMT
1)The pitcher characteristics of S. rosea are somewhat different (larger hood, big lip, etc.) than those of S. purpurea. For example, the lip is thicker for S. rosea (2.6-7.5 mm) than for S. purpurea (0.7-3.1 mm). The lip character has been shown, in subsequent papers, to be particularly reliable. 2)Sarracenia rosea is the only Sarracenia with pink petals (except for some hybrids). The petals of S. purpurea are brick red to purplish red. 3)The flowers of S. rosea are larger (petals 4.5-6.4 cm long), and are on shorter peduncles (16-35 cm), than you see in Sarracenia purpurea (petals 2.2-5.3 cm; peduncles 22-79 cm). (From www.sarracenia.com/faq/faq5542.html)
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kath
Full Member
Posts: 79
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Post by kath on Feb 28, 2008 3:54:30 GMT
More information: Symbiotic mites serve as flags for potential realignments in our present classification scheme of the Sarraceniaceae. Members of the genus Sarraceniopus (family Histiostomatidae) are small, pale, slow-moving mites that inhabit pitchers of the Sarraceniaceae. Feeding stages of all the species of Sarraceniopus appear to live only in pitchers. In this specialized habitat, these mites filter-feed upon bacteria, which are usually abundant there. Four species have been described in Sarraceniopus. In addition, I have discovered at least 10 undescribed species in my studies of the Sarraceniaceae. The mites possess two clear advantages for use in the systematics of the plants: their high degree of host specificity and their likely cospeciation with the plants. One example of how the mites are useful in the systematics of the plants is the support they provide for the recognition of Sarracenia rosea as distinct from Sarracenia purpurea, since different mites live in these two hosts. cars.desu.edu/faculty/rnaczi/PitcherPlntSystematics.htmPitcher shape (lip width, mouth diameter, and pitcher width) in Florida panhandle populations differed significantly from pitcher shape of all other populations, even after accounting for environmental correlations. In contrast, the northern and southern subspecies of S. purpurea (the latter exclusive of the Florida panhandle populations) cannot be distinguished based on these morphological measurements alone. These results support a recent proposal that identifies the Florida populations as a distinct species, Sarracenia rosea. www.amjbot.org/cgi/content/abstract/91/11/1930?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=sarracenia&searchid=1&resourcetype=HWCIT
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Post by Alexis on Feb 28, 2008 23:26:58 GMT
Which purpurea are you referring to? There are more physical pitcher differences between ssp. purpurea and ssp. venosa than between ssp. venosa and var. burkii!
Correct. Why should this be enough to make it a whole new species though? Petal colour is given great weighting purely because of the visual aspect. At what point does the colour become important? If the petals were red-pink instead of pink/white/magenta, would it be less of an argument to make it a whole new species because the petals weren't far enough away from the red of the northern plants?
Yes, but ssp. purpurea and ssp. venosa flowers are also different. Why not sarracenia purpurea and sarracenia venosa?
And I assume ssp. purpurea has different hosts than ssp. venosa? Isn't this just a location factor? Surely plants further south will host southern species of mite. Would hosts transported from burkii into venosa not be able to survive?
I don't deny this, but you cannot have ssp. purpurea, ssp. venosa and species rosea. The only classification I would support would be species purpurea, species venosa and species rosea OR species purpurea ssp. purpurea / venosa / rosea. Personally I would ditch rosea and only use burkii, but that's my opinion.
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Post by BarryRice on Feb 29, 2008 20:30:29 GMT
This horse is being beaten a lot, but I'm offering up the notion that while I use the system of S. purpurea subsp. purpurea, S. purpurea subsp. venosa, and S. rosea, I'm pondering the evidence that the first two entities should just be merged and give us S. purpurea and S. rosea, with no subspecies delineations. There is interesting support for such a perspective.
B
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Post by Brian Barnes on Mar 1, 2008 12:28:41 GMT
Gosh, i must be getting old. I still call mine "Louis Burke" ;D LOL! Bri.
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Post by Aidan on Mar 1, 2008 18:08:55 GMT
Perhaps it's a little revisionist, but here's a thought... How about we have just S. purpurea - period, full stop, end of story, game over!
We could also have plain old S. flava. Who needs varieties? The point at which one variety shades into another is arbitrary anyway and confuses everyone.
Then we could do away with the entire S. rubra complex which thoroughly confuses everyone... and of course we can lump S. oreophila in there as well, since the molecular studies show it's actually S. rubra.
Fewer species, subspecies and varieties. Problem solved! ;D
(How seriously you take this suggestion is entirely a matter for your own conscience.)
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Post by marcel on Mar 1, 2008 18:30:15 GMT
(How seriously you take this suggestion is entirely a matter for your own conscience.) What conscience Aidan? I just love keeping things simple ;D
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Post by ICPS-bob on Mar 1, 2008 18:40:23 GMT
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Post by rsivertsen on Mar 2, 2008 0:10:18 GMT
This horse is being beaten a lot, but I'm offering up the notion that while I use the system of S. purpurea subsp. purpurea, S. purpurea subsp. venosa, and S. rosea, I'm pondering the evidence that the first two entities should just be merged and give us S. purpurea and S. rosea, with no subspecies delineations. There is interesting support for such a perspective. B Maybe it's too short! Is there a caveat or rule that specifies that a name should not be longer than the plant? Perhaps we’re getting into what the original concept of Linnaeus had tried to instill in his scientific nomenclature, to avoid these complex names that translated from its original Latin to what turned out to be something like: “green, short pitcher-plant with strange, but large hood, short flower scapes, growing several meters from grandpa’s outhouse by a stream, near a flat rock” ?
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Post by Alexis on Mar 6, 2008 23:06:12 GMT
I'm interested in the notion of of merging ssp. purpurea and venosa Barry. To me, purpurea ssp. purpurea is the most distinctive of the three! If I was to merge anything, it would be "rosea" and venosa!
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Post by BarryRice on Mar 6, 2008 23:27:13 GMT
There's an interesting paper that came out of the Ellison lab that showed (if memory serves) that in S. purpurea, the subsp. we call venosa occupies territory that has never been glaciated, while what we call subsp. purpurea is in previously glaciated territory. And if you chart various characters against climate characters, you see a smooth gradation. The implication is that subsp. purpurea occurred as a northward invasion of subsp. venosa, and that since there are smooth correlations between taxonomic, environmental, and geographic characters, that really we're just seeing variation in a single entity, i.e. S. purpurea.
I encourage the interested reader to refer to the original paper, and not to rely upon my faulty characterisation.
I believe the paper of import is Ellison, Buckley, Miller, and Gotelli, 2004, Morphological variation in Sarracenia purpurea (Sarraceniaceae): geographic, environmental, and taxonomic correlates. American Journal of Botany. 91: 1930-1935.
Cheers
Barry
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Post by ICPS-bob on Mar 7, 2008 0:11:22 GMT
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