Friday, October 4, 2013

Promethean plants indeed: Rosularia and their cognomen (more blasts, mostly from the past...)

Prometheum (Rosularia) aizoon
Most of these are images that Ann Frazier scanned from the distant past..alas, many of the plants remained there--but at least we have their images. I knew this first lot as Rosularia for decades--then a few systematists found reason (no doubt genetic) to distinguish eight taxa--most of which I have grown...the first, alphabetically, is this wonderful miniature from Turkey. These are now named for the mythical Greek hero who stole fire and shared it with mortals, and spent eternity pinned to a cliff in the Caucasus--where, incidentally, his namesake Crassulaceae are wont to be pinned as well...

Prometheum (Rosularia) chrysantha
This is the one that is relatively widely cultivated--several large scale wholesale nurseries mass produce it in the United States. I am quite sure none of them have caught on that it has a new generic name...This was the first of these I ever grew--a plant shipped to me through the mail forty years ago this year by Joel Spingarn--who is best known for growing conifers (the Conifer Society had its very first meeting in his back yard) but he has grown many other plants as well...I have grown wide masses of this over the years, although at present it may be missing from my garden (horrors!)...its flowers are underwhelming, alas. Very pale lemonade color--I suspect everything in cultivation comes from a single clone. I wonder if there are not some brighter yellow forms in nature that would justify the name "chrysantha"...

Prometheum (Rosularia) hausknechtii
The revision does not recognize this taxon as a Prometheum, but surely it must be. Unless it's just another variation of P. aizoon? Perhaps it's all moot since this plant has perished...

Prometheum (Rosularia) muratdaghensis
I grew this gem for years as "Rosularia turkestanica" (I actually collected the latter in the wild a few years ago--a very disappointing plant, alas!)...but muratdaghensis is a delight: I have grown this from before the time it was named!

Prometheum serpentinicum with cacti and haworthia...
One of the loveliest "rosularia" is this tiny morsel from Sandras Dag where it is local and quite rare--it grows superbly and blooms itself to death unless you constantly propagate it (which is well worth doing)...this trough is much sparser this year...time to propagate!

Prometheum (Rosularia) rechingeri

Obviously closely allied to muratdaghensis, this smaller species has equally enchanting, colored rosettes, but smaller flowers and not quite as showy...after growing such masses for so long (which produced buckets of miniscule seed) I noticed it's almost gone from our collections...repeat after me: propagate! propagate! propagate!

Prometheum (Sedum) pilosum
I always suspected this wasn't a sedum! and sure enough, it's now one of the select prometheums! Alas--would that it would self sow!

Prometheum (Sedum) sempervivioides
The gorgeous rosettes are almost as lovely as the blooms: another biennial that has settled into a new generic concept: I have listed all the Prometheums currently known to science, except a rare Greek one (P. tymphaeum). I suspect there are a few undescribed species pinned to the high cliffs of the Caucasus and other Western Asian cliffsides that are occasionally pecked at by eagles!

Rosularia sedoides
I first grew this gem as "Sempervivella alba' --I think it's relatively comfortable resting under Rosularia for the time being...Much later blooming than the other species, and Himalayan in distribution...

Rosularia sempervivum
I have obtained a half dozen or more plants inder the name Rosularia sempervivum or R. libanoticum that are all relatively similar, or not. I love them all, and will continue to obtain these... this is a relatively pale specimen....

Rosularia sempervivum var. (very dwarf)

Rosularia pestallozae
Quite similar to the dwarf Rosularia sempervivum but it came under another name...

Rosularia sempervivum
This one produced enormous rosettes--worth growing in their own right!

Rosularia sempervivum ex Urs Eggli coll.

This one was paler pink than the rest and is quite persistent in the garden...

Rosularia alpestris
I still grow this, but never again as well--in fact I found it on the high Tian Shan growing in big masses in a meadow. When I returned to the meadow the following year to collect seed, the area this grew had been bulldozed for construction...I've also found it in Pakistan--a huge range for any plant!

Rosularia serrata

I end with a scan of a transparency I took in 1994 in Western Turkey, not far from Smyrna, that shows how rosularias grow in nature. Alas, this species is recalcitrant in cold winter areas, but the others we have grown successfully grow in similar situations in more central Anatolia.
I think a better name for the genus would have been Proteum: they are quite protean in their look, and more importantly, this removes the onus of eternal punishment on high, Caucasian cliffs. After all we're pampering them on miniature urban and suburban cliffs instead!


  1. Amazing collection of plants. Another set for me to watch out for.

  2. Hi Panayoti, You are the Indiana Jones of the Plant World. Your problem maintaining these species in cultivation makes me wonder how many individuals of a species must be maintained to sustain a colony. Long lived perennials can be propagated from cuttings. However, maintaining annuals or biennials means some minimum number must be kept if the species are to remain in cultivation. Too few genetically distinct individuals will bring genetic doom.

  3. Rosularia/Prometheum can be relatively long lived in a perfect microclimate. My problem has been maintaining a collection of many thousands of plants--I sometimes forget to propagate a plant that is quietly declining. And suddenly it's gone. And of course, many of these are not terribly long lived, so it's a sort of juggling to keep them in the air...fortunately, there are many hobbyists in the Denver area and nurseries that grow rare plants, so sometimes a plant I have lost reappears at one of them...and we can be off and running again! A few of the rosularias have really taken off--and these are not a problem (muratdaghense, serpentinica)--fortunately, their seed is extremely long lived: we re-generated Rosularia globulariafolia from 20 year old seed recently! So all hope isn't lost (better ransack my seed files this winter...)


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