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Article: Drosera graminifolia and D. spiralis

Paulo Minatel

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Hi there,

A new article on Brazilian Drosera taxonomy just got published:

Gonella, P.M., Rivadavia, F. & Sano, P.T. (2012) Re-establishment of Drosera spiralis (Droseraceae), and a new circumscription of D. graminifolia. Phytotaxa 75: 43-57.


Here the abstract of the paper:

"Drosera graminifolia and D. spiralis have long been considered conspecific, but new morphological and ecological data support the recognition of these taxa as distinct species. Both species are here described and illustrated, including observations on ecology, habitat, and conservation status, together with a distribution map, line drawings, photographs, and a table containing the distinctive characters."

Here are the answers for those who ever asked themselves about the differences between Drosera graminifolia and D. spiralis (as you can see in the article, there are many)!

Here you can see a brief illustrated guide, showing the main differences between both species: https://www.facebook...70251137&type=1

And here, one of the figures of the article, illustrating Drosera graminifolia:


In case you want the pdf of the article, just PM me sending your email address! :wink:

All the best!

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Glad you liked it! ;)

Robert Gibson asked me a very valid question yesterday: did spiralis really deserve to be a species? Or better as a subspecies?

After first seeing these plants in the wild in the early 90's, it was immediately obvious to me that the northern plants (D.spiralis) were different from type D.graminifolia. But it took me 20 years of field and lab work to finally acquire a better understanding of just how different they truly were, together with the help of many friends and botanists along the way, including in the latter years my co-author Paulo Gonella. And the main question discussed always seemed to be the taxonomic rank: species, subspecies, or variety?

According to botanical rules, the geographic separation alone is sufficient to classify graminifolia and spiralis at subspecific level, and as not varieties. But we could go on for another 20 years or more discussing here whether all the morphological/ecological differences listed in our article justify a separation at species level, since everyone has slightly different species concepts and there is no quantitative line that you can draw in the sand that would convince everyone one way or another.

However in my mind, the choice for species (versus subspecies) boils down to two main arguments:

1.) "Forget the long thread leaves" argument: Thread-leaved sundews are rare. The long narrow leaves are an unusual character that stand out and draw all our attention away from the rest of the plants, something that is hard to ignore and that we repeatedly keep going back to whenever discussing the taxa involved. It's a taxonomic distraction. So much so that some people have even suggested in the past a close relationship between graminifolia/spiralis and filiformis/tracyi - although we now know for sure that this is merely a good example of convergent evolution for leaf shape. And it was thanks to discussions with Barry Rice about the separation of D.filiformis and D.tracyi that I was finally convinced that D.graminifolia and D.spiralis are also good species. Barry had a very simple argument: forget for a minute that filiformis and tracyi have long thread leaves, pretend they have a more typical spatulate-leaved flat rosette, and now apply all the other characters that distinguish the two taxa. It took me a few seconds to work out this mental exercise, imagining something like a D.spatulata as a starting point (representing D.filiformis), and then applying one by one the characters that distinguish D.tracyi. The resulting imaginary plant was not only very different from the original D.spatulata model I'd started with, but it was something that I would most likely consider a good species -- if I ever came across it in Australia. Surprised at my own conclusion (until then I was not convinced filiformis and tracyi should be different species), I immediately performed the same mental exercise with graminifolia and spiralis (which are far more different from each other than filiformis/tracyi), starting with a D.spatulata-like model representing graminifolia, and then adding one-by-one the main characters that distinguish spiralis:

- much shorter petioles

- much larger stipules

- less hairy backside of the leaves

- totally different glandular trichome type on leaves and scapes

- glandular tentacles present on sepals

- irregular circinate leaf vernation

- thicker leaves with semi-circular petiole cross-section

- leaf apex narrower

- smaller, rounder seed

- separate geographic distribution

- different kind of habitat

- different flowering periods

And I was immediately convinced: morphologically and ecologically these characters would be more than sufficient to separate at specific level any two closely related rosetted taxa with spatulate leaves. D.graminifolia and D.spiralis were finally good species in my head.

2.) The argument for conservation: D.graminifolia is a narrow endemic (whereas D.spiralis is widespread) only know from small populations on 4 peaks. Although inside a park, they sit right next to huge mining areas (see Google Earth), which in the late 90's nearly caused their extinction due to some kind of pollution/acid rain effect that annihilated nearly all the vegetation on those mountain tops (and certainly resulting in the extinction of other endemic species that I have no knowledge of, as well as possibly locally eradicating G.violacea and U.reniformis - BTW, Caraça is the type location for the latter). At the type site of D.graminifolia on the Pico da Carapuça, the population was reduced to a single healthy adult plant in the early 2000's and the beautiful orange Sphagnum carpets I'd first seen in 1992 were gone. Fortunately, they have recovered quite well over the past 10 years, I am not sure why. Whatever pollutant was being spilled must've stopped. I'm sure it was pure luck though, and not a conscious decision from the mining companies, assuming they even knew what they were causing. Therefore, moving forward (and ignoring the possible dooming effects of the genetic bottle neck caused by the population crash), the best chance for future conservation of this taxon (in case it ever runs into trouble again) is to classify it at species level. Saving a mere subspecies simply doesn't attract as much conservation attention.

Best wishes and happy holidays to all! :)

Fernando Rivadavia

Edited by Fernando Rivadavia
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I've grown small plants of both. They didn't looks the same; nor did they grow the same. Pretty clear to me.

I just wish these gems become a little more available...

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Yes, all plants previously known as "graminifolia" that are not from the Serra do Caraça, are in fact D.spiralis.

Unfortunately true D.graminifolia is not only rare in cultivation, but also in the wild where it is critically endangered.

Best wishes,

Fernando Rivadavia

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Hi Aymeric,

The D. graminifolia "Nortensis" are the D. spiralis plants from the northern range of this species, around the towns of Grão Mogol to Itacambira. This paragraph of the paper deals with this "morphotype":

Rivadavia (1996) suggests that plants from the northern range of D. spiralis could be classified as a distinct subspecies, based mainly on their more robust habit. This variation in the leaf size is exemplified in Fig. 4, which depicts: the shorter petiole commonly observed in plants from the southern range (Fig. 4C), as well as the long petiole more common in plants of the northern range (Fig. 4D). Albeit the recorded extremes in leaf length, a continuum of variation is clear when comparing plants across the distribution range, and no other distinctive characters were observed for the northern populations which would justify separation as a distinct taxon at subspecific or varietal rank.

All the best,

Edited by Paulo Minatel
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Congratulations, really a very informative article.

The differences are now clearly visible.

These special trichomes for sure are the biggest difference but on the first sight it´s nearly impossible to see this difference, the much longer petioles and the rather broader leafes are better visible.

Are the leafes less "succulent" as in D. spiralis?

I know a "plant" that also shows some of these traits but it has only 13cm long leafes, oh, i will better not continue.....

Of course i took a closer look at my plants and of course all of them are D. spiralis as they are not from the Serra do Caraça but a few differences have been visible. Partially the translucent secretion has different colouration, the size seems also to be different and the eglandular hairs along the margins do not exist on the petioles.

Here are some pictures (not my best ones) of the petioles of the Diamantina form, i hope nobody has something against it and if it´s the case i can delete them immediately:

nearly all trichomes are colourless, only a few are reddish or yellowish and not a single hair is visible



Here are some pictures of the Itacambira form:

nearly all trichomes are reddish and the petiole is hairy along the margins



and something "closely related", just a joke



Best regards,


Edited by Daniel O.
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Thanks Fernando, in each case the leafes i examined have been from two different seed grown plants and the differences have been the same.

Yes, the last two pictures show the petioles of young plants of D. camporupestris x spiralis.

Best regards,


Edited by Daniel O.
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  • 1 year later...

Hey Dani, did you ever obtain D.graminifolia? I would be very interested in someday seeing an artificial cross between D.graminifolia and D.spiralis. I wonder what the glandular trichomes would look like in the hybrid... Would we have something intermediate between the "TSG" and regular glandualr trichomes? Or would we have a mixture of both?

P.S. Any new hybrids to show us? :)

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Hi Fernando,

no, i do not grow D. graminifolia. Hopefully i will receive some D. graminifolia seed one day.

For sure it would be interesting to see the hybrid between D. spiralis and D. graminifolia. Do you think that this hybrid exists in nature?

About new hybrids, yes, i think i can show these days my next one, it´s again a hybrid with D. spec. "Bahia". :wink:

Best regards,


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