New Zealand Cactus and Succulent Journal V47N04 pag. 64-66

The genus Frailea Britton & Rose 1922

by Nick Perrin

Probably not now amongst the most well-known of cacti, the genus Frailea was dismissed by Gordon Rowley (1978) in his "The Illustrated Encyclopedia of Succulents" as

"real miniatures....A Frailea flower is a rare sight: mostly the species are cleistogamous and all one sees is the relatively large fruit full of seeds"

and that is all he has apart from the information that these plants belong in the same group as the better-known genera of Neoporteria, Notocactus and Parodia. I see in browsing through 1967 issues of this journal that the genus was probably better known then, with articles and advertisements for seedlings, but poor growth and lack of flowers probably resulted in a loss in popularity.

I became interested in these plants mainly because they are dwarfs, and partly from a desire to try anything. A friend suggested that if it was miniature cacti I wanted, then I should go for Blossfeldia. (I would have, but they seemed to be hard to come by, then at least, and a bit difficult to grow.)
The genus Frailea was erected in 1922 by Britton and Rose to accommodate some distinctive, dwarf plants previously classified under Echinocactus. They recognised 8 species, and named the genus in honour of one Manuel Fraile, a Spaniard born in Salamanca in 1850, who for many years cared for the cactus collections of the US Department of Agriculture, Washington DC.
By the time the noted Maltese cactophile John Borg published the first edition of "Cacti" in 1937, there were 15 species of Frailea described. Borg's book was the only comprehensive cactus book available when I began collecting, and is probably much neglected now -1 must admit this is the first time I have opened it for years - but it is a very useful update of Britton and Rose, with a gardener's bias, and it softens the huge jump from Britton and Rose to Backeberg's "Cactus Lexicon". Britton and Rose is also indispensable, because it is such a cornerstone, containing information you just can't get from Backeberg or any of the more modern texts.
David Hunt wrote the chapter on the cactus family in Hutchinson's "The Genera of Flowering Plants" published in 1967 - one of the fundamental and most respected of botanical texts. He referred to Frailea as " including 12 weakly-defined species".

Backeberg had about 16 species in his Cactus Lexicon, published just after he died in January 1966. When Walther Haage's additions were included in the English edition of "Cactus Lexicon" in 1976, there were 35 species described, but probably many are invalid or synonymous.
The type species is Frailea cataphracta which was described as Echinocactus cataphractus by Dams in 1904. The earliest described plant, however is F. pumila, described in 1838 as an Echinocactus. Their geographic distribution is Uruguay, Paraguay, southern Brazil, the narrow strip of Argentina that pokes up between Paraguay and Uruguay. This distribution is much like that of Notocactus. They are also reputed to inhabit Bolivia and Colombia, but this seems hard to believe, and there is a theory that it is wrong.
Frailea colombiana has never been found in habitat at the type locality after the first description. Ray Pearce in the Cactus and Succulent Journal of Great Britain, Vol 40 No 3 1978, reports that the late Mike Taylor "unequivocally stated that F. colombiana did not come from Colombia, and cited a "Rancho Colombia" at some more plausible location in Paraguay, Uruguay or Brazil as being the correct position, but he wasn't aware of any written verification of this theory.
The seeds in particular have been likened to those of Astrophytum, and a suggested relationship between the Mexican-Southern USA Astrophytum and the South American Frailea on this basis was supposed to make the occurrence of F. colombiana in Colombia believable. The similarity of the seeds is coincidence, and other anatomical differences between Astros and Fraileas suggest they are not closely related, much as you would expect given their widely-separate natural ranges.
CULTIVATION
"...they lack any sense of permanence. As young seedlings they can be quite attractive, but slowly and surely they become distorted and ugly, and a proportion will lower their defences and succumb to lurking diseases. This is also a feature of the allied Parodia and Notocactus to a slightly lesser degree, especially in regard to root loss in Winter..." (Roy Mottram quoted in the British Journal referred to above.)
This is certainly true in my experience. I once had a F. alacriportana and lost it. But one of my earliest cacti is F. cataphracta which is said to be difficult. I didn't know that, so I accidentally grew it beautifully. F. colombiana I grew from seed with some success and no losses, and the most pathetic, 1 inch, wrinkled, lop-sided cactus I ever grew was a thing called Frailea HU 183 (I think it was), the seed of which I was given. All plants proved identical, and it looked like a dwarf version of F. alacriportana. When I dug a few out of the seedling trays, the root disturbance apparently caused the death of all of those in an ever-expanding circle around them.
The seeds are freely produced, and germinate exceptionally well when fresh, but after a year germination is poor, and after a few years it is nil.
The more attractive species seem to be difficult to grow, so I tried grafting. One of my most successful grafts ever is of F. magnifica which grows well, while my F. asterioides (F. castanea) died after growing marginally well for several years grafted. (I am not keen on grafting, and have only ever done these two, an Echinopsis crest and an Opuntia clavarioides.)
The plants need partial shade for optimum growth, but will commonly grow all right in full sun. I have only once seen flowers, and they appeared to open only in afternoon sun when was is hot and steamy.
One thing you can count on with growing Frailea from seed is that they will all be identical with none of the normal variability that you see in other plants. As they are self fertile, they likely to be clones, and the normal species variation which results from cross-pollination will be suppressed even in wild populations. This means that inherited characters will become really entrenched, and the same species from different places may be so different as to be described as a separate species. This does happen in all cacti (or indeed, in all plants) and especially in Frailea I suspect. Of course, if this happens for a long enough time, then they do become separate species.
All things considered, there are a few attractive species and many nondescript ones, but if it's miniatures you want, then Blossfeldia may be the answer.