European Utricularia

[andreasfleischmann]

Dear Utricularia-lovers,

In the following thread I’m going to try to introduce to you some of the fascinating European aquatic Utricularia species (of which wagging tongues say that they all look the same, haha! ). Maybe I can illustrate some of the vague differences to tell those neglected beauties apart from each other .

The photos were made on several fieldtrips to bogs and moors (both fens and hill moors) in southern Bavaria, that’s why two of the seven aquatic species that occur in Europe are missing: The common free floating aquatic U. vulgaris is very rare in southern Bavaria (south of the Donau river, where it is replaced by U. australis), at most sites within this range it seems to be rather introduced by CP enthusiasts than occuring naturally. The critically endangered U. bremii is confirmed for Germany from only one single fish pond in northern Bavaria, and I still haven’t seen it in flower there, that’s why I don’t show it here, too .

The most common of the small, affixed species is Utricularia minor. It grows both in shallow pools in peat bogs and hill moors as well as in alkaline fens.

A typical habitat of U. minor (and U. stygia): shallow water-logged depressions, mud bottoms (“Schlenken”), ditches and pools in a hill moor in the Allgaeu, southern Bavaria:



U. minor usually forms dense mats, quite often filling up the entire ditches and pools.



It is the smallest of the European aquatic Utrics, forming traps on both leaves and lateral stolons (however stolons can lack in minute specimens). Usually it’s just one single trap per leaf segment.



The other affixed aquatics can be found in bloom very rarely, however U. minor seems to flower more readily (especially in dry summers, when the pools start to dry up).



Flowering U. minor can be told apart from any other aquatic Utricularia (except U. bremii ) by its long, narrow lower lip (the margins are usually bent downwards) and its very short, saccate spur. The yellow rim on the palate is quite characteristic as well.

[andreasfleischmann]

Another moor species is Utricularia stygia. This species has often been misidentified as U. intermedia, and therefore it’s range in Europe is still unclear. At least in southern Germany, it is much more common than U. intermedia! Most “U. intermedia” in the herbaria are in fact U. stygia. See the differences between those 2 species below.


Typical habitat of U. stygia: a nutrient poor mud bottom in a peat bog.

Like U. minor, U. stygia usually fills up the whole pools with its leaves and stolons.


In contrast to U. minor, U. stygia (and the next two species I’m going to show) develops two different kind of stolons: green creeping stolons, which bear the segmented leaves, and pale underground stolons, which bear only traps, not leaves. U. stygia has huge traps on the underground stolons, and does only occasionally form a few single traps on the leaves:


Green surface stolon with leaves, and pale subterrean stolon bearing the traps.

The leaf segments of U. stygia are thin and narrow, and have an acute tip. Moreover, the margins of the leaf segments bear several acute spines, or projections. This can be seen especially well in the close-up photo. You can find traps on some of the leaves. (In contrast, U. intermedia never has traps on its leaves, but exclusively on the underground stolons. The leaf segments are broader in that species, the tip is more rounded, the margins appear blunt (as the spines are only very very short in U. intermedia. See photos below under that species for comparision). Leaves of U. stygia:



Close-up, note the acute tips and long spines on the margins of the leaves:


U. stygia is one of the European Utrics that are flowering only very very rarely. That’s most likely because it’s of supposed hybrid origin, and thus seems to rely more on vegetative propagation by division and hibernacula. In July 2007, I had the luck to find one single specimen in flower in a peat bog in the western Allgaeu, when I was botanising there with Jan Schlauer. Well, actually Jan was the lucky guy to discover that single flower .


Jan, who is searching scientifically accurate for flowering U. stygia, with gps and other scientific devices (dowsing-rod? ).


Jan, who has finally found a flowering specimen of U. stygia – by chance. . I don’t know which experience was more mind-blowing: the exclusive sight of a flowering U. stygia in its natural habitat, or the exclusive sight of a Jan Schlauer getting excited in the natural habitat of U. stygia, haha .

And here it is, flowering U. stygia (accompanied by Drosera intermedia):





Note the short acute spur, which is pointing downwards from the lower lip:





U. stygia can even grow outside water at the margines of the mud holes, where it seems to thrive well growing in Sphagnum. These “growth forms” of most European Utrics have been described as “forma terrestris” or such, which is completely nonsense! It’s one and the same plant than the affixed aquatic, just growing outside the water!

[andreasfleischmann]

U. intermedia grows in ditches and depressions of moors and bogs as well, but it’s more common in deeper pools and pond margins (especially if those get silt up with vegetation). It seems to like slightly more nutrient rich waters than U. stygia or U. ochroleuca do, and it also prefers slightly calcareous conditions.



Typical habitat of U. intermedia: a reed-filled bay, Ammersee lake, near Landsberg (where huge ring snakes, Natrix natrix, can be found as well. Unfortunately they had been way too fast for my camera. That’s why I was concentrating on the immobile Utrics, haha! )



As mentioned above, U. intermedia never bears any traps on its leaves, the large traps can only be found at the underground stolons. The leaves are broader than those of U. stygia, the tip is more rounded, and the margins appear blunt.



The differences between U. intermedia and U. stygia can be noticed well in the following photo, where both species grew sympatrically in a peat bog in western Allgaeu. U. stygia (narrower leaves with acute tips!) is the one within the white line:



Flower of U. intermedia:




The broadly tubular spur of U. intermedia is about as long as the lower lip of the corolla, and it has a typical constriction at half of its length. This is how flowers of U. intermdia differ from the related U. stygia and U. ochroleuca (both with a shorter spur, about half as long as lower corolla lip, narrowly tubular, without any narrowing or constriction)

[andreasfleischmann]

One of the rarest bladderworts in Germany is Utricularia ochroleuca s. str. (i.e. in its strict sense, as some authors lump it together with U. stygia). It is critically endangered and only confirmed from 2 locations in Germany: from a tiny bog near lake Bodensee, Allgaeu, and from the moor-like margins of an oligotrophic fishpond in northeastern Bavaria, close to the Czech border. I visited both locations in 2007.
It’s confined to shallow pools and ditches of very nutrient poor hill moors, like the one below (it’s the site near the Czech border).


U. ochroleuca is very similar to U. stygia in shape and size of the leaves, however it does bear traps on almost every single leaf of the surface stolons (photos from the Bodensee site).







Like U. stygia, U. ochroleuca s. str. can survive as a terrestrial in very shallow pools, too.




Whereas the plants from the Bodensee site seem to be sterile (no flower was ever observed there so far), the plants from northeastern Bavaria seem to flower more regularly (like those from populations in the Czech Republic do. The Czech plants seem to have more vigour ).
Although “ochroleuca” means “lemon yellow”, I could not note any difference in colour compared to other yellow Utricularia flowers. Well, they are all.... yellow! .





Compare the short narrow spur to that of U. intermedia (see photo above):


Flowers of both U. ochroleuca and U. intermedia for comparision (from cultivated plants).

[andreasfleischmann]

And last but not least, the most common Utricularia species of southern Germany: the freely floating aquatic U. australis. It’s growing in almost every kind of stagnant water, lakes, ponds, pools, drainage lines in moors and bogs. No matter if the water has a low or high pH-value, and it even grows well in rather nutrient rich water.

Typical habitats of U. australis in moors: drainage ditches and moor pools (“Moorauge”, how’s that called in English?)




Flowers of U. australis:






And finally, here’s the Utric-quiz:

At this site, a peat bog in the Allgaeu, 3 different aquatic Utricularia species are growing sympatrically in that shallow ditch. Can you tell which ones? Have fun!

Andreas

[BarryRice]

Hey Andreas,

If you take your species list,

U. australia
U. minor
U. intermedia
U. ochroleuca
U. stygia

and replace the U. australis with U. macrorhiza, you have the exact same list of suspects that I'm dealing with in California.

Do you have any criteria other than quadrifid glands, for telling U. ochroleuca from U. stygia? With time, I'm leaning towards treating both of these latter species as being (at least in California) of hybrid origin, with the differences between the species merely being a matter of variation in the way the parental characters are expressed in the hybrids.

What's going on in Europe might be very different, however.

But most importantly, thank you for that wonderful photograph of Jan!

B

[rsivertsen]

Hey Barry,

Might I add U. inflata and possibly U. subulata to that list as well!? - Rich

[BarryRice]

Hey Rich,

I should have been clearer, in that the list of plants I gave are those plants that can be a source of confusion (and interest). In California we also have U. gibba as a native. Now, as non-native, as you noted, we have U. subulata, U. inflata, and also U. bisquamata . Maybe more, but I haven't found them yet.

[Brian Barnes]

Hey Barry,
Seeeee......I'm not the the only one that dances happily when I find CP in the field. Jan's doing the "Stygia Shuffle" ;D ;D
Happy Growing,
Brian.