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Andreas Fleischmann

Drosera anglica var. pusilla/ D. kihlmanii

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Today I found the time to sort out some more habitat photographs of mine ;).

One of my favourite fens (or marl bogs, i.e. a swampy area where nutrient-poor but calcareous water seeps through the ground) is a small protected site between Munich and Rosenheim, in southern Bavaria.

In these nutrient poor soils of high pH-values several rare plants grow, including a few CPs.

calcarous_habitat.jpg

Overview of the marl seepage area, dominated by reed (Phragmites australe). Note the scattered growing rosettes of Pinguicula vulgaris.

P_vulgaris_LW01.jpg

Interestingly, the plants of P. vulgaris growing at this site have a very pale flower colour, some flowers appear almost pure white with age.

P_vulgaris_LW02.jpg

Moreover, the leaves of P. vulgaris from this site usually turn dark maroon in late spring/summer when exposed to full sunlight.

P_vulgaris_LW03.jpg

The rosettes first have a yellowish-green colouration (like usually found in P. vulgaris) in early stage of growth. This colour is kept in plants growing in the shade of taller grasses and sedges.

But what makes this location so special to me is the fact that you can find D. anglica growing there, side by side with P. vulgaris! A Drosera growing in alkaline calcareous soil! This ecological feature of D. anglica, that it can tolerate soils of high pH (growing conditions which would kill almost any other Drosera!) can be explained as a heritage it got from one of its parents (you may be familiar with the hybrid origin of autopolyploid D. anglica ;)), namely D. linearis (the only other Drosera I know of that usually grows in alkaline marl soils).

D_anglica_pusilla_habit02.jpg

However, these marl-bog D. anglica stay much smaller in size than their sisters growing in peaty sphagnum bogs (which is still the preferred habitat of D. anglica).

D_anglica_pusilla_leaf.jpg

The leaves are smaller, and the lamina is obovate in outline and much shorter than in “typical” D. anglica. The leaves of these fen-growing D. anglica almost look like leaves of D. intermedia!

D_anglica_pusilla_habit01.jpg

Flower stalks of the “marl-bog-form” of D. anglica are much more stunted than in D. anglica growing in peat bogs, and they are usally only single-flowered (rarely bearing up to 3 flowers).

This minute “form” of D. anglica has been first described as “D. anglica var. pusilla” by the botanist A. O. Kihlman from the Kola peninsular of Skandinavia/Russia (interestingly the type is from a sphagum bog!), and was turned into a “D. anglica f. pusilla” by Diels. A new (and superfluous ;)) name, “Drosera kihlmanii” was given to this minute D. anglica by the Russian botanist Sergei Ikonnikov in 2001 (in the Fl. Vostochnoĭ Evropȳ 10, in Russian).

For several years, I thought that this small size and other different features would just be ecologically induced by the less appropriate growing conditions for Drosera anglica in the fen bogs. However, plants in cultivation grown from seed (which I was allowed to collect from this site for research purposes) stay that small in size, leaf shape and number of flowers is constantly low, too! Even plants grown in acidic soils, i.e. in milled sphagnum or pure peat, side by side with “typical” D. anglica, stay minute and few-flowered in cultivation! Thus maybe this phenotype is indeed genetically fixed? This would mean that a distinct taxonomic treatment of this diminuitive D. anglica (by using a distinct name on whatever taxonomic level) is probably even reasonable. I personally will choose the original variety rank for this taxon from now on ;).

An additional fact that did convince me of D. anglica var. pusilla being really different from D. anglica var. anglica: I discovered “typical” D. anglica in several Alpine marl fens this year! These D. anglica kept their “typical look” (long petioles, long narrowly obovate to oblong lamina, long flower stalks bearing several flowers), although they grew in alkaline soils (identical growing conditions to D. anglica var. pusilla, which I can only confirm from a few marl bogs in SE Bavaria so far).

However I admit that more research (and cultivation experiments) will be needed to reveal the true nature of that strange D. anglica var. pusilla ;). But at least I can already exclude any hybrid influence of either D. intermedia or D. rotundifolia!

And last but not least, this special fen is famous for some other rare bog plants, like the endangered orchid Liparis loesielii, or some more common plants of alkaline bogs, like Tofieldia calyculata (Melanthiaceae (formerly placed in the lily-family, like almost every monocot ;)). I hope you enjoy...

Liparis01.jpg

Liparis02.jpg

Tofieldia.jpg

All the best,

Andreas

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Aside from peat, do they need someting like sand for drainage?

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Fantastic photos!

Here in Japan, you can see D. rotundifolia growing in some limestone regions.

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Hi Andreas,

That is an interesting report. Have you tried crossing this variety with the normal one?

Thanks for sharing your pictures, experiences and thoughts.

Regards,

Sebastian

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Thanks for all the information about this unique plant Andreas. I have been growing indoors and studying the diminutive “alpine form”. Here are my observations: It grew terribly slow till having leaves little more than one inch long, and then stopped increasing in size. Decreasing the light hours promptly stimulated winter bud formation. When a bud was well formed I bagged the pot and put it in the fridge for 4 weeks. After taking it out, I found that it was infected with a fungus and had begun to rot; but it soon went into rapid growth and a single flowered stalk appeared. The plant is tiny, even smaller than the tropical growing Hawaiian D. anglica which I also grow.

     I’d like to also mention that I managed to cross pollinate the first flower of my alpine plant with that of the Hawaiian. The hybrid seedlings are growing well. It will be interesting to see how they turn out.

~Ivan in Southern California

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