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Dudleya Albums

Since ‘discovering’ Dudleya during a visit to California, in 2008, I have been baffled by their variability in habitat and the difficulty in deciding what species (singular or plural) that I’m seeing. I travelled along the Californian coastal area from Eureka, CA, close to the border with Oregon, down to the southern point of Baja.

Naturally I looked for an authoritative work in literature to help me. I learned that Reid Moran’s 1951 thesis ‘A Revision of Dudleya’ was still the respected reference work, but not readily available, although I now know at least one person with a photo copy of it. I was therefore very pleased to make an impulse purchase of the one and only published monograph of the Genus, or rather genera: The Dudleya and Hasseanthus Handbook. I was both pleased and disappointed as ultimately it has provided little help in identifying the Dudleya (and Hasseanthus) that I have seen and photographed since then.

I was however impressed with the total lack of pretence by the author that his book would solve all my problems of identification. I’ll quote the following from his ‘Nomenclatural Policy section:

‘… regardless of how accurate the descriptions or how good the color pictures it will be nearly impossible, with perhaps a very few exceptions, to POSITIVELY identify a plant. Many of the species have such a great deal of variation within them that at the extremes they might well be considered different species altogether.’

‘However, to further confuse the issue, the species hybridize in nature and tend to intergrade between one location and another, so even though the two extremes may be distinct species they may be connected by a series of intermediate forms leading to the possibility forms leading to to the possibly erroneous conclusion that they are all a single species.’  

How refreshing! Reading this section for the first time three years after I bought the book, I feel faced with the same dilemmas.  So why did the author carry on writing his book and why do I still refer to it? Mr Thompson died in 2009, so I can’t ask him that question. I refer to the book for its pictures of named Dudleya taxa from specific locations. Sometimes they help to put a name to a plant that I have photographed at that location. It’s a problem that I have also encountered in the Cactaceae as soon as I start taking anything more than a casual interest in a specific genus. There are more useful observations to be quoted:

‘ Even though plants grown in containers may differ from those found in the field this is not thought to be objectionable since the majority of collectors will probably be growing their plants in containers this making identification easier.’

WRONG! My need is to identify plants found in nature. But is does provide an interesting insight. If plants look markedly different in cultivation compared to those in nature, then this could indicate that the differences seen for these genera are largely influenced by environmental factors, rather than genetic ones.

It seems that the identification of Dudleya s.l. relies heavily on the characteristics of their inflorescence. It is therefore unfortunate that my observations are mainly from early Spring, February to early April, when most plants are not yet in flower and last year’s flower spike remnants have disappeared.

With these wisdoms in mind and numerous images of Dudleya in habitat as memories of past travels, I intend to post them here, mostly as ‘Dudleya sp.’ in the hope that people more experienced then I can suggest a name AND provide a reason why this is the correct name for these plants.

Fortunately I have found that at least some taxa, such as D. pachyphytum and D. (H.) blochmaniae ssp. brevifolia, are clearly distinct and that I have seen and photographed plants that match their description at the locations from where they have been cited. They each have an album included below.

In any event, I hope that you will agree that these albums show some wonderful plants, often growing in very photogenic settings and that despite the lack of botanical names, you will enjoy browsing through them.




s.n. D. blochmanniae (Eastwood) Moran ssp brevifolia (Moran) Moran


Other photo albums are for plants at specific locations for which I’d welcome ID suggestions, particularly if it is possible to provide the rational for such suggestions.


Various Internet resources list two species of Dudleya that are endemic to Isla Cedros: Dudleya pachyphytum and Dudleya cedrosensis. Some of the Internet resources report that the name D. cedrosensis is invalid. Detailed searches for images of the illusive D. cedrosensis failed to produce results. So what were the Dudleya, other than the relatively easy to ID D. pachyphytum, that we saw during our three days plus stay on the island?

The variable D. albiflora has been reported from the island and we saw some plants that might be this species

Are these that Species?


There was a very distinct plant that grew forming large clumps, but seemed to be very limited in distribution. Could this be D. cedrosensis nom. inval.? Is it even a Dudleya? No buds, flowers or remains seen


And what name should we use for this plant? Could it be a hybrid, with D. pachyphytum as one of the parents? So D. pachyphytum x X?


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