(Editor's Note: This article was originally published on May 30, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
Crassula is a monster genus of hundreds of species and many hundreds more hybrids and cultivars. There is no way for me to cover them all in a single article... nor would I want to since it is not one of my areas of ‘expertise' (I lose a lot of Crassulas still... until I get through that hurdle I will try to avoid pretending I know a lot about them). Many species of Crassulas have a unique way of growing with their leaves stacked upon each other and with the stem running right up the middle of them. I call these the stacked Crassulas, though I don't know if anyone else does, so don't start thinking this is some official descriptive term. In a sort of therapeutic effort to separate these stacked Crassulas apart in my mind, I am writing this article to introduce the new succulent grower to these fascinating plants, and to help me sort out what's what.
Some Crassula perforatas in one of my pots (along with numerous other succulents)
From looking through many sites on the web it has become clear that I am not the only confused person out there, and that many others mix up these names, call this that, that this etc. I am not sure that all the forms of these stacked Crassulas have been named officially, or if they have, that information has not been released to the public.
a variety of stacked Crassulas in pots along with other succulents; this green plant is an unknown one- looks like Crassula perforata but has flowers more like Crassula rupestris... who knows?
In some sense, all Crassulas are stacked with leaves surrounding a central stem. But the plants I am going to concentrate are the ones that grow straight up and not the mounding or rosette varieties. The basic species most of these are patterned after are Crassula perforata and Crassula rupestris. Then there are the dinky stacked Crassulas, mucosa and pyramidalis. And there are the short, clumping stacked ones, Crassula marchandii and columella. And then there are the Crassula capitella thyrsiflora varieties which qualify as stacked plants. And of course there are probably dozens more, but these are some of the most common ones found in cultivation. Then of course there are many more dozens of hybrids of these, and of other Crassulas that happen to form stacks. Some are common (listed below) and others fairly rare (not listed below).
variety of stacked Crassulas in the yard
Crassula perforata- This plant is also called String of Buttons and (incorrectly) Crassula Pagoda (and a variety of other common names several nurseries have obviously made up). It also has a lot of synonyms, though the only one I see used frequently is Crassula conjuncta. Crassula perforata is an aggressively suckering plant (seems to spread below ground, but only centimeters away) with a skinny, 2mm stem upon which are stacked succulent triangular leaves of various colors (depending on the variety). These colors also change a bit depending on the season, temperature, water availability and exposure to light (which is probably redundant, as those parameters are what change with the seasons). The triangular leaves are stacked in such a way that they give the impression of a tall, square-edged plant. In this species, there is just a little bit of space (several millimeters) between each leaf. Flowers in spring are not too exciting, and most gardeners trim them off after realizing this, as the dead, dried sticks are very unattractive once flowering is over. This plant does not seem to branch much, at least not in the way the similar Crassula rupestris does.
Crassula perforata colony in botanical garden, and then in pot and my own garden
Several varieties of variegated Crassula perforata
This is a pretty hardy plant and I have abused it severely (not a rare plant and cheap and easy to replace) with overwatering, underwatering, blasting exposure to 100F+ full sun, deep, dark shade, crammed it into other containers with seemingly no root space to spare... and it just grows through it all. Full, hot sun does make it look sad and can really damage it if it's not acclimated to such abuse. It is a plant that seems to prefer a bit of protection in mid summer in a hot, dry climate. But it still looks good enough in sunny exposures that I have not been prompted to much plants I put in such locations.
Shots showing the less than exciting flowers of Crassula perforata This plant had a leggy part and flower removed, and now is growing some new foliage
It is a great potted plant, filling small spaces with a number of colorful, tall geometric shapes. Eventually these plants grow ‘out of the pot' draping over the edges and hanging down, only to bend back up towards the sun again, making them ideal plants for low hanging pots. Eventually these get leggy and have to be cut back (though I rarely do as the legginess doesn't bother me too much). They definitely need to be cut back after flowering or there will be a multitude of dead twigs coming from your plants (if one doesn't remove these dead flowers, eventually they become necrotic and fall off on their own).
Crassula perforata getting too 'leggy' and in need of hacking back; variegated plants flowering in succulent pot, and several varieties used in pot landscape
There are several variegated versions of this plant, and some green ones as well. I do not know if the variegated versions all have individual identities, or if they all just fall under the same taxonomic category of ‘variegated' String of Buttons. But some are pale green with white strips, some are multicolored with pinks, reds, oranges and pale yellows, and some are bright green with only hints of variegation. One larger plant I called Giant Pagoda is some variation that looks a lot like a Crassula rupestris, but has the spindly flowers of Crassula perforata. I made this name up, so one very likely will discover this plant called something else in a nursery.
More shots of variegated Crassula perforata, and the 'Giant' String of Buttons (pale green plant)- I thought this might be Crassula rupestris (see below) but it flowers like Crassula perforata
Some confuse Crassula perforata with Crassula perfoliata, a much larger and brilliantly flowering plant that looks nothing like Crassula perforata.
Crassula perfoliata in first photo and Crassula perfoliata variety falcata in second
Crassula rupestris, or the Rosary Plant or Vine, is a larger plant similar stacked but with fleshier leaves that are more lancelote rather than perfectly triangular, and are often two-toned. Also this plant tends to have a greener, fleshier, wider stem than Crassula perforata does. This is a highly branching species, as are most of its hybrids and cultivars. The flowers of Crassula rupestris are probably the main distinguishing feature, being pink and globoid and actually fairly ornamental, as opposed to the linear, weedy flowers of Crassula perforata. It is this last characteristic that helps me the most tell the two species apart... but when not in flower, I can be mistaken at times.
Three color variations of Crassula rupestris (sure look a lot like Crassula perforata!)
This species is similarly tough and resilient at is Crassula perforata and I have not distinguished anything different in their cultivational requirements. It too makes a great pot plant for tall or hanging pots and is even more pushy about crawling over the edges of the pots and curving back up towards the sun. However these branch a lot and sometimes the parts of the plants hanging out of the pots become so heavy that they snap off or even uproot the entire plant and fall out. The good thing is they can be cut back and each cut off section can be left to dry a few days and replanted somewhere else (they appear to root rather easily).
Flowers are quite different from Crassula perforata; this last photo is of a particularly large version of Crassula rupestris, with leaves nearly 2x larger than in these other plants
Hybrids of these two species abound, and one of the best hybrids is that made by crossing these two (Crassula perforata x Crassula rupestris var marnieriana) : the result is a plant called Baby Necklace which is a very hardy and ornamental plant with small, rounded, fleshy leaves tightly stacked (no stem visible between the leaves) and usually multicolored (green centers with red edges)... and resembles a string of beads like one would find on a necklace. This plant does not branch much and stays fairly small (6"-12" tall) and has excellent drought and cold tolerance, though prefers some sun protection.
Crassula 'Baby's Necklace' photos
Crassula Baby's Surprise is a dinky, unicolor (pale green) version of this same hybrid
Crassula perforata x Crassula rupestris v. marnieriana Baby's Surprise
There are several varieties of Crassula rupestris that are fairly commonly found in cultivation: Crassula Tom Thumb is a variety of this species called Crassula rupestris var commutata and is basically a miniature version of Crassula rupestris. There is a variegated version of this plant, too.
Crassula rupestris var commuttata aka Crassula Tom Thumb variegated version flowering plant in my yard
shade grown and old Crassula Tom Thumbs
Crassula rupestris var monticola is a wonderful variety with slightly smaller, thick, rounded leaves that I have not had a whole lot of luck keeping alive over the winter. I will try again in the future as this is an extremely ornamental version of this species.
Crassula rupestris var monticola in partial sun, and then full sun. Last photo is a flowering plant in a show
Crassula rupestris var marnieriana (sometimes listed as Crassula marnieriana) is also referred to as the Jade Necklace or Chinese Pagoda, and is a pale green, small plant with closely stacked rounded leaves that looks a bit like a miniature version of the Baby Necklace plant.
Crassula rupestris var. marnieriana (second photo by Bootandall- thanks)
Two other stacked Crassulas that one may find fairly common in cultivation are Crassula mucosa (aka lycopodiodes) and Crassula pyramidalis. The former is an extremely common plant often found at most garden outlet centers and looks from a distance like pale green grass. But close up one can see it is a succulent make of extremely small, firm closely stacked pale to lime green leaves. I have this plant in full sun in my yard at it has never given me a problem (though it did get burned a bit when temps got down around 25F). I have also grown it in deep shade but it gets pretty weak and leggy in that environment, and eventually rots and dies. It is not a super ornamental plant- more just an interesting one. Crassula ‘Imperialis' appears to be a slightly thicker variety of this species.
Crassula mucosas in my yard (full sun and probably too much shade) variegated Crassula mucosa
Close up Crassula 'imperialis' (photo by Xenomorph- thanks!)
Crassula pyramidalis is far less common but much more ornamental with extremely thin, closely spaced flat leaves forming perfect square columns 1"-4" tall and about 1cm in diameter. It seems to be a relatively hardy plant but I haven't had this one more than one winter. It is pretty slow growing.
Two other plants I especially like in this stacked group are Crassula marchandii and Crassula columella. I group them only because they are relatively short, compact, suckering plants that from mounds and are extremely ornamental. However, that is where the similarities end. Crassula marchandii is a shiny-leaved plant, usually deep green to dark maroon (depending on how much sun or cold it's getting). It has barely rounded leaves that are stacked to create a smooth, square column about 3"-5" tall.
Crassula marchandii for sale, and in a show, and lastly, out in too much sun
Crassula columella is a pale green to lime-yellow- green plant with more round-edged columns and often the leaves have reddish margins. The leaves of this species are not shiny.
Crassula collumella in my yard, and in a show
Both these plants are slow growing, hate full sun and are relatively easy to rot from overwatering. However, they are similarly easy to desiccate from under-watering, so some extra attention needs to be paid when growing these two. I have had pretty good success in pots with these plants, but not much out in the garden.
Crassula capitella is an extremely variable species with several varieties which look quite different. Variety thyrisflora is a stacked plant with longish, lancelote, pointed leaves that sit right upon each other but with each successive leaf being little shorter than the last. So this creates tapering stacks and makes for a highly ornamental look. There are two very different plants both identified, as far as I can tell, as Crassula capitella thyrsiflora. One is about 10x larger than the other so I have a hard time believing they are the same species AND variety. But I have no further information leading me to these plant's true identities, so for now I will call them Crassula capitella var thyrisflora giant form, and Crassula capietlla var thyrisflora tiny form (I suspect this latter form is really something else entirely). Both plants are easy to grow, with the latter even qualifying as a greenhouse weed, often showing up in nearby plants. Both have wonderful color in bright light (full sun) with the larger form showing a lot of red (similar to Crassula capitella Campfire) and the smaller one a dark maroon. The smaller plant has very flat leaves while the larger form has thicker, fleshier brittle leaves.
Crassula capitella var thyrsiflora 'large form' for sale, and then same plant a month later planted in the yard
plants growing agressively in ground, and in pot
Crassula capitella var thyrsiflora 'dinky form) in pot and garden
plants flowering in pot and yard
Crassula Buddha's Temple is a hybrid of Crassula perforata var minor and Crassula pyramidalis. This is a greenish skinny, tall version of Crassula Ivory Tower (see below) with flat, thin, pale-green leaves stacked tightly and folded up at the edges, forming a perfectly square column about 1" in diameter. It develops the most wonderful spherical red, orange or white flower stuck to the top of the plant. This plant is fairly hardy in the garden, but quickly gets leggy, falls over and then tends to rot if not cut back and replanted. It has really wimpy roots and seems to like being watered regularly or it dies.
Crassula Buddha's Temple in greenhouse, in my yard, and plants for sale
Crassula Buddha's Temple flower detail, and two shots of my plant branching and growing in pot. In both these photos you can glimpse the similar but silvery plant Crassula Ivory Pagoda growing near the bottom of the photos for comparison
Crassula Ivory Pagoda is a hybrid of Crassula falcata X barkleyi (Crassula barkleyi is another great stacked Crassula, but pretty rare in cultivation- see below). This plant is not one of my favorites and is a pretty wimpy garden plant. It is basically a larger, silvery, less symmetrical vesion of Crassula Buddha's Temple.
my own (not for long- these die on me easily) Crassula Ivory Pagoda and several photos by Happenstance (thanks)
Crassula Moonglow is a wonderful and extremely common stacked hybrid of Crassula deceptor X falcata. This plant is perfectly square in cross-section and ivory colored (one of the reasons it commonly gets misidentified as Ivory Tower or Ivory Pagoda), with thick, somewhat rough leaves without any space between them. I have rotted a few of these, but for the most part this is a hardy hybrid with excellent full sun tolerance (does not do well in full shade- etoliates, falls over and rots easily) and pretty good cold tolerance (down to 27F at least). It is an excellent potted plant as well as garden plant. Columns can get as high as 18" but usually fall over without support long before then. Eventually it suckers at the base and makes an attractive colonly of square, ivory ‘buildings'.
Crassula Moonglow does great in pots as well as the yard
several shots of flowering Crassula Moonglows
There are several stacked Crassulas with the name Ivory in them, and I have gotten these confused on many occasions (I think they are still some mistakes in the plantfiles I need to correct someday). Crassula Ivory Pagoda is a relatively common hybrid between two uncommon Crassulas: Crassula decpetor (an extremely ornamental species with rounded leaves but not one I have a photo of) and Crassula barklyi (aka Crassula teres, or Rattlesnake Crassula), another pretty rare plant with very tightly stacked, rounded, thinner leaves. All three plants (this hybrid and the plants its made from) are all touchy in my experience and I have had no luck keeping any of them alive. This hybrid is not the most ornamental to me, with pale, ivory wavy leaves closely stacked like a bunch of pale green pancakes starting to dry out and piled on each other somewhat haphazardly. These all rot far too easily to be members of my collection.
Crassula Ivory Tower is a more recent hybrid (between Crassula ‘Moonglow' and Crassula falcata. This hybrid is much tougher and so far I have two I have not killed yet. It is more square in shape with thick, ivory leaves. It is a pretty slow-growing plant but tolerates moderate sun, shade and the usual abuses my care has to offer. I have often mistakenly identified Crassula Moonglow as this plant, but Crassula Moonglow is about half the diameter and a much more vigorous grower... but it certainly is somewhat similar in appearance.
Crassula Ivory Tower in my garden
Several other stacked Crassulas below
Crassula barkleyi aka Crassula teres is a great looking plant, but hard to find in cultivation. I have never tried to grow this plant
Crassula plegmatoides in show, and my plant