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Post by Sockhom on Oct 13, 2011 22:02:00 GMT
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Post by Sockhom on Oct 18, 2011 11:43:04 GMT
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Post by wireman on Feb 24, 2012 16:43:12 GMT
I recently finished reading though the North America book (I was part of the map research team, my brother was the one who made the maps) and had a thought on the taxonomy of S. purpurea ssp. venosa var. burkei, a.k.a. S. rosea. Based on the differences in clumping growth, nectar roll size, leaf length, flower color and dimensions, and disjunct distribution, shouldn't it at least be considered a subspecies? S. purpurea ssp. purpurea and ssp. venosa and divided into subspecies based on the same merits. There are enough differences to classify the plant as S. purpurea ssp. rosea, or S. purpurea ssp. burkii, in my opinion. Either way, more research needs to be done in differentiating these taxon.
Graham
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Post by Dave Evans on Mar 14, 2012 1:09:20 GMT
S. rosea *is* a cryptic species. Botanists have looked for S. purpurea subspecies venosa in the gulf coast and in gulf coast herbariums. However, it has never been located or even been recorded in the gulf coast. All specimens are S. rosea, a cryptic species. Please see: en.wikipedia.org/wiki/Cryptic_species_complexAll McPherson has done is repeat Schnell's theory that S. p. v. has a range which extends from eastern Texas, across the Gulf Coast and up into central Virginia. This is nonsense. S. p. v. is restricted to northern Georgia, South and North Carolina, southern and central Virginia. It is exceedingly rare anymore. As per Dr. Donald Schnell, "I don't think much of S. rosea. I don't even look at purpurea anymore, after studying them locally in Virginia." This quote Dr. Schnell gave to me, gives me no confidence what-so-ever in his "opinion" of something he 'doesn't bother looking at.' S. rosea currently has a much larger range and larger populations. But, if the rate of expiration of viable habitat continues, it will soon be as rare as S. p. v..
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Post by Aidan on Mar 14, 2012 20:50:36 GMT
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Post by wireman on Mar 15, 2012 19:38:48 GMT
I was talking with Dave about this last week.
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Post by wireman on Mar 22, 2012 16:30:37 GMT
Forgot to mention this as well. There are several distinguishing features of S. rosea that were never mentioned in the book. The big ones are; S. rosea does not have a groove at the top of the hood like S. purpurea does, the hood vein fractals are completely different, S. rosea has a more vertical hood than S. purpurea, S. rosea's pitcher body is more bulbous on the bottom than S. purpurea (also influencing the more acute hood angle), etc. The flower is also a very different shape. S. purpurea's petals curve under the umbracular style, while S. rosea hold the petals flat, unlike any other Sarracenia.
Looking at the table the Stewart provided in the book of distinguishing characteristics it even present enough differences in the features that he uses to justify the subspecies to include S. rosea as a subspecies, at least (clumping habits, flower space height, hood size, etc.) The massive break in the range is even more evidence. I think Stewart is just working on so many books at once that he doesn't have the time or energy to concentrate on matters like this.
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Post by John Brittnacher on Mar 24, 2012 0:46:09 GMT
Another thing about Sarracenia rosea is it requires a much longer growing season than Sarracenia purpurea. I had a a very large plant when I moved from northern California to southern Oregon. The S. rosea declined every year until it became either let it die or give it away. I gave it away. The Sarracenia purpurea subsp. purpurea are doing better here. I didn't have a S. purpurea subsp. venosa in Davis but I do now and it is doing OK.
What I also noticed is in Davis it was not always easy to tell S. rosea from S. purpurea subsp. venosa. But here there was no question as the pitchers of S. rosea were more tubby.
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Post by wireman on May 17, 2012 22:59:37 GMT
What I also noticed is in Davis it was not always easy to tell S. rosea from S. purpurea subsp. venosa. But here there was no question as the pitchers of S. rosea were more tubby. There are some big differences, you just have to look for things you wouldn't normally think of. Being an artist, this is easy. S. purpurea has a prominent notch in the center of the hood. This is absent in S. rosea, as the peak of the hood is rounder. The color and texture of the developing pitchers is also very different. S. rosea is more of a tan color and furry, while S. purpurea is a reddish orange and smoother. I've also noticed that the glaberous v. pubescent traits of S. purpurea between ssp. purpurea and ssp. venosa doesn't exactly hold up. I found a purpurea from Wisconsin that has a pubescent exterior, very pubescent. |
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Post by Apoplast on May 17, 2012 23:48:35 GMT
Hi All - This seems like it should be really easy to solve. Stop basing decisions on solely morphological characteristics, and do a well geographically sampled molecular phylogeny (has that been done yet?). Until then, the arguments are futile. If var. burkii/rosea comprises a distinct lineage from all the other purprea lineages, then an argument can be made for it being a distinct species. If it is subsumed within any part of the purpurea lineage, then it is not (unless someone wants to start splitting up the rest of purpurea). Easy. Now someone just has to do the work (assuming nobody has yet).
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Post by meadowview on May 18, 2012 12:59:51 GMT
Hi Apoplast:
There have been a number of both molecular and morphological studies on the taxonomy of S. purpurea and S. rosea. If you do an on-line search you can read all about it, and my research and conclusions, in my 2010 Ph.D. dissertation "Ecological and genetic status of the purple pitcher plant, Sarracenia purpurea L., in Maryland and Virginia". Short story - S. rosea a distinct species with one entity for remaining group, S. purpurea, with the subspecies concept not supported at the morphological or molecular level.
Sincerely,
Phil Sheridan, Ph.D.
Director
Meadowview Biological
Research Station
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