Friday, January 18, 2008

Unsung Hero (Hylocereus undatus)

Pity poor Hylocereus undatus.1 Though a perfectly interesting species in its own right, you'll never see it when you're looking over the plants at your local Lowe's or supermarket or garden center or wherever you buy them, even if you're looking directly at it. Why's that? Because 99.99% of the time, you're seeing this:



These brightly-colored cacti are actually two different species of cacti grafted together. The top plant in these photos is a Gymnocalycium species, often called "moon cactus," which has mutated in such a way that it is unable (or maybe just unwilling: they seem kind of spoiled if you ask me) to produce the chlorophyll it needs to photosynthesize. These have been around for years: I remember seeing them as a little kid. The ones I remember, though, were always kind of a neon red: the pinks and yellows and oranges and purples like in the picture are a semi-new development.

The Gymnocalycium produces offsets pretty easily, even when grafted, and the offsets so produced can be grafted to a new base, perpetuating the plant, though it's my understanding that even the best grafts only last a few years, as the base grows faster than the Gymnocalycium. After that point, the difference in speed between the two becomes too great for the graft to hold together, and the two split apart. Some of the sites I ran across in researching this one seemed to be suggesting that the Gymnocalycium, if removed from the base and replanted, will remain colored until it dies from lack of food; other sites implied that severed grafts would spontaneously begin to produce chlorophyll even though they never had previously, and could be planted on their own. My personal suspicion is that both are true: the "purple" grafts, if you look closely, do contain some green, towards the center of the plant:



So they probably could begin making food for themselves if they really needed to. Peanut butter sandwiches, at least. At the same time, the neon yellow and orange and pink give no indication of having any green pigment in them whatsoever, and so I would guess that those probably couldn't make it on their own. We do have a few plain green Gymnocalycium at work, but they don't do anything terribly interesting and just look like your ordinary small green beanbag-shaped cactus. A couple of them do color up a little in the summer: they stay green but have a red / purple cast to them, especially on the most exposed portions of the plants. It's not especially attractive: mostly they just look kind of burnt.

But who cares about the Gymnocalyciums anyway, right? What we're really interested in is the base, the sad little, put-upon, servant of a plant that's doing all the heavy lifting.



The above is my own personal plant. I got it from Lowe's, after an excruciating wait to see whether anybody else was going to take it. It was one of a number of grafted cacti they had, all of them Gymnocalycium/Hylocereus types, but on this particular one, the graft had come off, and there were sprouts from each corner of the Hylocereus. I wanted to buy it, but the original plant was like $3.47, which seemed like a lot for a plant that was kinda, you know, broken. So I waited, and waited, and then finally there it was, waiting for me, on the half-price racks.

It's done well for me so far. It grew really quickly when it first arrived, and has settled down a little bit now that we're in the middle of winter. One of the bigger surprises was the sudden appearance of aerial roots from the center of the stem segments:



This is perfectly normal, just not something I was expecting to see. The aerial roots are like aerial roots on anything else: they're not mandatory. If you don't like them, you can cut them off; if they dry up and die, the plant isn't necessarily hurt any.

The thing I was most surprised about, though, was that when I started looking into it, I found out that this was the same plant that gives us the dragon fruit, or pitaya. As a bonus surprise, I found out that "dragon fruit" really existed: I'd actually assumed that there was probably no such thing. (Based on the name, it sounded like a marketing ploy to me, and it's not like I'd seen any in the grocery store.)2 But they are real, and they look like this:

Photo: Allen Timothy Chang, at the Wikipedia entry for pitaya


I think you'll agree that "dragon fruit" seems like an appropriate name. The interior of the fruit is full of small, crunchy black seeds, which are (I hear) pretty easily sprouted; the pulp surrounding the seeds is white, pink, or red, depending on its ancestry. It is apparently typical for the fruit to be served chilled, and the flesh scooped out of the rind with a spoon. The taste is said to be something like a melon or kiwi (the crunchy seeds contribute to the kiwi comparison): sweet, but not intense.

The flowers are also kind of a big deal:

Photo: "roychai," at the Wikipedia entry for pitaya


The flowers are short-lived, opening only for one night. They're pretty damned elaborate, as you can see from the picture, and are heavily scented. By all accounts, they're awesome flowers, but alas, I've never seen one of those in person either.

Plants have to be large, if not old, in order to set blooms and fruit. Mine clearly has a ways to go. They are supposed to grow faster and do better in general if you give them something to hang onto, like with Monstera deliciosa, though since they get big (20 feet is not unheard of), you're going to want to choose something you can add to over time. They will climb trees in the wild, though they're not picky, and will attach to burlap-covered poles, concrete walls, slow-moving pets, or whatever.3 At least a couple places I ran across on-line seemed to be suggesting that it's reasonable to expect blooms at about two years old and / or two feet tall; to get fruit you need somewhat bigger plants, and the flowers have to be pollinated. I haven't seen anybody address the question of whether plants are self-fertile.

Care is fairly typical cactus, though since this is a jungle species (the Hylocereus genus as a whole is native to the Caribbean and Central America south to the northmost part of South America), it's somewhat more flexible about certain things. Full sun is desirable indoors; the plant can be moved outside during the summer but should be shaded from the hottest summer sun, and obviously one will want to make any big shifts in light level somewhat gradually. The plant adapts to a pretty wide range of soils, and tolerates very hot and very cold conditions (up to 110ºF/43ºC, down to freezing or below, though they can only withstand short periods of cold, so don't push this too hard). Humidity is essentially a non-issue.

Propagation is said to be pretty simple: they root easily from cuttings that have been allowed to dry for a day or two: stand the cutting up on a well-draining soil and water when the soil gets dry, and the plant will handle the rest. It's also supposed to be a piece of cake to sprout seeds, if you're lucky enough to get a fruit to take seeds from: my understanding is that a moist but not soggy, fairly loose soil mix, seeds sprinkled around on top, and a plastic bag over the top of the mix is all you really need. Seedlings can be transplanted when they've grown beyond their seed leaves.

I'm a little clueless on watering; I've been going with the standard cactus approach of letting it get pretty dry between waterings, which with my plant winds up being about every 10-14 days. So far, so good, though I have seen a few things around the net that suggest that this needs to be cut back even further during the winter. So far, there are no complaints, so I'm inclined to keep doing what I've been doing. But we'll see how it goes.

I'm going to assume mealybugs can be a problem, because when the hell are they ever not, but I haven't had any yet.

They're known for getting kind of top-heavy. Wider, shallower pots are sometimes advised for this, to lower the center of gravity, but you still have to bear in mind that the roots only need as much soil as they need, and you can't move them into a pot that's larger than they need without there being some consequences.

I don't expect to get fruit from this plant. I don't even really expect flowers, to tell the truth. But I do like it, all the same, for being this totally cool plant that was hidden in plain sight: crazy flowers, alien-looking fruit, a tree-climbing cactus, and the only time I ever saw it, it was relegated to being the low-key servant for some lazy-ass Gymnocalycium that won't even make their own chlorophyll. Not that you should go to your local plant supplier and start liberating the Hylocereus by knocking off their grafts: that would be wrong, if amusing ("Grow, my pretties! Grow and be free!"). But, you know, sooner or later you'll see one where the graft has come off on its own, through normal handling or whatever,4 and depending on where you find yourself, you may be able to get it for a song, if you ask the right people. And it'd be worth getting.

-

Photo credits: fruit and flower as noted in text; all others are my own.
1 (Some or all of this post will also apply to the closely-related species Hylocereus trigonus. The differences between H. trigonus and H. undatus are small enough that I couldn't determine how anyone tells them apart. So feel free to pity H. trigonus as well, if you are so moved.)
2 (I can sometimes be too skeptical for my own good.)
3 There is considerable on-line disagreement about exactly how fast these grow, with some sides saying they're practically a blur and others saying that they take forever to get anywhere. Based on the speed of my own, thus far, and the information at this site, I lean towards blur, but your results may vary, especially if you and I actually own different species. Selenicereus spp. are similar-looking, and also have big Las-Vegas-showgirl flower production extravaganzas, but appear to work much more slowly. Also different Hylocereus species can, I think, reasonably be expected to grow at differing speeds. Anyone with actual information about this, even anecdotal, is encouraged to share in the comments.
4 Thus far, nothing like this has happened to the batch we got a couple weeks ago, for which I am grateful. They've actually even sold pretty well. I'm not a fan of grafted cacti, never have been, and I liked them even less well when I read that the graft isn't stable for more than a few years, so I was kind of against ordering them in the first place, but apparently the rest of the world likes the damn garish and fake things better than I do.


34 comments:

waterroots said...

Oh my...I never knew that about this plant. I thought it was (top and bottom) one plant. Well, you certainly do learn something new every day. Poor thing. I wonder if it would sell as well if it went solo.

And I've seen that fruit at the grocery store, just recently though. I wondered what it was, even poked it a couple of times. But I never bought it; it's something I've never seen before and had no clue what the heck it is, or what it might taste like. Well, now I'm curious enough to want to try it, especially because of the 'Unsung Hero' in this story...

Thanks for the info; it was very interesting.

Sarah S said...

I always see these at Home Depot. It seems to be the only plant they can sell without damaging/nearly killing first.

I like it that you've touched on the topic of calculated and opportunistic plant-shopping in this post. The method behind each of our plant madnesses is very interesting to me - I guess I just wish I could go plant shopping with all of you!

sheila said...

Interesting to see what a dragonfruit likes. I'm addicted to the dragonfruit flavored "vitamin water" drink!

I have a red one of these things that has been sittin on my kitchen windowsill for way more than a couple of years. The red has faded over time, the red part has grown some, I don't think the green one has at all. I splash a little water in there every few weeks? months? whenever I can't remember doing it last. The soil is so compacted that there's hardly any left. But the graft shows no sign of separating. (Maybe with better care, the bottom would be outgrowing the top and it would become an issue?))

mr_subjunctive said...

I haven't actually had one of the grafts myself, like I said, so I was just going by what I've seen elsewhere w/r/t how long they last. The Hylocereus part of it certainly is capable of growing fast, if it wants to, though they don't seem to grow as much when they're grafted, probably because they lack a growing tip. I'll have to look into this and do an unfinished-business post if I find out anything interesting.

Tracy said...

I did see one of these at the grocery store tonight. 4 bucks, so I had to try it. Inside is more or less the same as a kiwi fruit. Flavor....coconutty.....very light, sweet taste. I thought they were pretty good, I would eat them again. I saved some seeds to, gonna have to try it out and grow my own.

maria elba said...

i, too, purchased one of these when i saw that the top part had dried up and fallen off and noticed a side shoot growing out with roots and all...i'm a sucker for plants that i know no one else will buy..anywho..i had no idea what this plant was and this brought me to you. i couldn't find it in any of my books...except one page about grafting cacti and all they talked about was the top colorful cactus and completely ignored what they were grafting it onto...so yes, i just wanted to thank you for such a great blog. and the plant thanks you since i can now treat it properly..i'm hoping she thrives this summer once i can get her outdoors in full sun...i live in colorado, so i basically have no real summer and just a nice extended spring and shoot straight into fall, but i like it that way...and now i'm done babbling, thanks again!!

playaj said...

a H. undatus at my place bloomed profusely last august. it even produced a pitaya, which went un harvested, but i think birds or other critters ate it. pictures: http://playaj.blogs.com/garden/epiphyllum_bloom_aug_2007_010.jpg, http://playaj.blogs.com/garden/epiphyllum_bloom_aug_2007_012.jpg
my hand measures 9-1/2 inches from tip of index to tip of thumb, so you have an idea how huge the flower is. no strong fragrance however. for the last 15 years, it has been slowly maneuvering up the side of a garage in San Diego, with the heavier top parts supported by still connected, but unused electric lines leading to an adjacent garage.

XP_2600 said...

Well, thanks for the nice information, i was breeding cactus for about ten years, i am no longer doing now, well i did many success grafting but i never do it with gymnocalycium, i would like ask you why always they use Hylocereus? dont you recommend another genus as a stock instead of Hylocereus?!

mr_subjunctive said...

My guess for why they always use Hylocereus as the base is because it's cheap and easy to grow as much as you need in a short time. Plus apparently it accepts grafts easily. There may be other species that would work as well, or better, but I don't know enough about the process to be able to recommend one.

XP_2600 said...

Thanks so much.

Anonymous said...

I have over 10 hylocereus in my backyard (in S. California), and the 4 plants that have bloomed so far are almost all in full sun (one this year made three fruit!).

If you are lucky enough to get blooms, they may even be self-fertile. However to get fruit, you'll have to help them by moving the pollen from the edges into the center part of the bloom (and you can only do this on the ONE night that they bloom).

So good luck ... hope you get some fruit!

Homegrown Evolution said...

Damn, I love this blog. I too thought those things were one plant. Who would have guessed the folks at the big box stores would be messing around with dragonfruit! Keep up the good work!

Anonymous said...

Well, that's a surprise. I knew these were two different cacti, one of them being obviously mutated.. But the pitaya part is a shocker. considering the price for a fruit (red skin, white flesh goes for $2 a pound, and red flesh is $8 a pound) and the price of the plant itself ($18 at Home Depot and around that price in nurseries), it's unusual to see this expensive plant in such an arrangement. But then, it explains the price for the sick-looking hybrid being so high.

Anonymous said...

Wow, this blog has been around a while. The comment I saw about the red flesh and the white flesh prices: The different colored flesh and skin comes from a different Hylocereus. I have been researching the plant for the past few months in little bits because I decided to look up dragon fruit to see if it was real and got hooked on the idea of having my own plant. So far I think I have found about 6 different types of Hylocereus and ehow says you have to cross pollinate to get fruit. I am not sure how true since it is the only site I have seen say that.

keith said...

I have one of these too. The graft died, and left the bottom. I was shocked to see side sprouts I thought the plant was dead for sure, then I thought the aerial roots were some spine. My plant has two long side shoots that are getting larger. I wonder if mine will live for a long time being I live in New York, U.S. and it's on my windowsill.

jnodrog said...

I recently rescued a cactus from a friend for whom it seemed a burden, and was ready to trash it. AFter some googling and picture identification, I have decided that it must be a hylocereus. It was big and sprawling, with half broken branches hanging over the pot. Almost as soon as I got it, it started sprouting new shoots vertically upward, growing up to about 3 ft in less than 2 months. The new shoots are also sending out masses of aerial roots. It also tends to have droplets on the aerioles of the new shoots, but sometimes these dry up into minute crystals. Her's the strangest thing of all: The soil remains moist for at least 3 weeks, so it seems to have stopped drinking water from the soil. Could it be that it is getting all of it's water needs from the air, and is even maintaining the moisture in the soil? Other cacti in the same room and same environment are bone dry within a week. Any ideas, Mr Subjunctive? By the way, I have spectacular photos of all of the above, and would post them here if I knew how.

mr_subjunctive said...

jnodrog:

My first thought was that maybe the roots of the plant have rotted out to the point where maybe there are no roots present to take up water, but that would be pretty obvious, because the plant would be falling out of the pot, and there'd be smells, and etc.

So then I thought mealybugs. Droplets of honeydew on the plant are common with mealybugs, mealybugs seem to like cacti more than most other plants, and for some reason plants that have mealybugs tend to use less water. I've never heard of a plant using that much less, but it's something to look for, if you haven't already. Especially since the plant was previously having problems for someone else, who may not have known what mealybugs looked like. (?)

Otherwise, I don't know. It certainly could be that it gets enough moisture through the aerial roots that it doesn't need to use the soil roots, though I've never seen that before, and I was under the impression that the aerial roots were mostly for anchoring the plant to a tree, not water-collecting. You didn't say whether the plant is in a particularly humid room, so I'm assuming it's in ordinary house conditions, which makes me even more suspicious about whether it could be absorbing that much water from the air.

Anonymous said...

This article helped so much. Thank you!!

Charlie said...

I saw many of these growing as epiphytes in Trinidad. I had one grown from offshoots of a grafted plant (the graft stayed on but i later lost both in a plague of mealybugs).

In response to XP_2600:
I've heard that Opuntia humifusa (O. compressa) makes excellent rootstock. It is often used for cacti that grow slowly or have weak roots and buried when they are mature. Cacti grown on opuntia are said to flower more prolifically and at a much younger age than those grown on another rootstock or even their own roots. It also has the advantage of being impervious to over watering, root rot, and cold (mine lived outdoors and survived -30 degrees) and is generally damn near indestructible.

Anonymous said...

Just bought myself one of these just to get rid of the top (never liked those anyway) I was just looking for the Hylocereus undatus but it's damn near impossible to get it here without the graft. Sowing one is not really an option either (Rather too impatient for it.)

Anonymous said...

Since several weeks my hylocereus has a new shoot and even started making an areal root. The shoot is rather long compaired to it's width but it is doing fine :) The time it took to make a shoot after it had been cut was surprisingly short. The new soil I put it in consisted of normal planting soil with a part of sand. I am keeping it relatively moist and thus far it is doing great even while the days are short :)

Without this page I would never have had this plant and I hope I will be enjoying it a whole wile longer :)

Ps. I am not quite sure which species it is as there are several species and there is no real way of telling which one it is at the moment =/

Suzanne Mastropietro said...

I've been curious about this fruit, but find them a tad pricey at my local Whole Foods to even try. I've also seen them at 99 Ranch, which is an Asian grocery, but, unfortunately, there were far too many bruises and lingering flies >_<

Perhaps a trip to Lowe's to purchase the plant will both satisfy my curiosity and add a little color to my drab living room environment. Thanks for the info!

misskatzen said...

I grew several of these from seeds, about 4 years ago. I love trying new and odd looking fruits whenever possible. The Dragon fruit definitely fit the bill. It was tasty, but I wanted to try my hand at growing one from seed. At the time I didn't realize the Dragon fruit came from a cactus, so I was quite surprised when I started looking up their care.

They took a long time to go from seed to seedling, and even longer to go from small, fragile cactus, to something I could transplant.

I've given all, but one, away to friends over the years. The one I kept had been the fastest grower and seemed to be the healthiest. Now, it's about three feet tall.

I water it like most of my other plants, but not like my succulents or cacti, with no problems. I can be a bit overzealous with the watering, so thankfully it's pretty hardy. I've had it in full to low light. It's always happy and is a fast grower. It even put on a couple more inches this winter.

Thank you for sharing your knowledge and wit. I've been on a plant identification kick today, and your blog has been a humorous stop. It's so getting bookmarked and visited again.

Anonymous said...

Another informative and fun profile.

In it you said "bear in mind that the roots only need as much soil as they need, and you can't move them into a pot that's larger than they need without there being some consequences." Have you a post regarding this position on soil and container size? If so, can you direct me to that post?

Thanks. Gonna just call myself Texas Anon. Never have posted a public query to a blog (or news articles and net things of that ilk)so not sure how to tag them stay private.

mr_subjunctive said...

Texas Anon:

I don't think I have a post about that question specifically, but the basic issue is that roots need both air and water. If you have too much soil around the roots, then when it's wet, it will block most of the air from getting to the roots, and the roots will die.

The situation is somewhat more flexible for plants being grown in containers outdoors, since those tend to dry out a lot faster, but for indoor plants, I don't recommend potting a plant up in a pot that leaves more than about an inch of space all the way around the roots.

Anonymous said...

Thanks. I was never sure why pot size is generally restricted. I have not followed that much myself. I tend to have a container available and stick a plant in and expect the plant to fill it up. Sometimes I put more than one plant in to get there faster, sometimes not. Generally nowadays it is outdoors in a usually dry,windy and low humidity situation so it's basically been successful, but it may explain some past failures.

Texas anon

jnodrog said...

I think I read somewhere that this plant is a saprophyte in its native environment. i.e. it does not necessarily grow in the ground but it hitches a ride on trees.

mr_subjunctive said...

jnodrog:

You mean epiphyte. Saprophytes grow on dead organic matter.

Anonymous said...

We moved to this house 4/09(SoCal Orange County). It had this ugly 6 foot cactus on the property line which I hated. So, in my infinite wisdom, I had the gardener chop the thing down to 1 foot when the neighboring house was empty. Well, the stupid cactus grew back to 6 foot in 1 year. As I was contemplating what to do with it, I staggered out one early morning(conquest unknown)and found these incredibly awesome yellow and white flowers on the cactus.Every AM there were new flowers and by noon the flowers were closed and droopy. So again last summer, the flowers were back and I am waiting for them again this year. We had some scraps that fell off the cactus last year and we potted them up in Supersoil and basically ignored them except for occasional watering. Those are now probably 4 feet high and are banished to a brick wall at the back of my garden. We had some work done on our house recently and the workmen somehow knocked some of the branches off the original plant. My husband(who is NOT a gardener)promptly chopped up the pieces and potted them up in Supersoil.Some of the chunks were stuck in the pots upside down! Needless to say, we now have 13 more plants to add to our menagerie. The plants are growing well with all kinds of strange appendages. I just found the name of these cacti somewhere and realized they are nightblooming. We have had no problems with pests so far. Did not know about the pollination thing-read somewhere they were hermaphroditic. May try the pollination thing if I can manage the hours. Anyway, thanks for your blog and all the great info. My new rule is to never chop any plant down until I have seen all four seasons of it. I am a long time, very amateur gardener and should have known better. I still don't like cactus.

LatinLady said...

Thank you for the excellent & extremely informative post. You have a trooper there. I have always been interested in learning more about the Hylocereus and am now going to purchase one to watch it grow in its own right on my New York window sill. You've converted me!

I'm guilty of purchasing a beautiful orange grafted moon cactus full of pups - At first for its beauty, then I decided to go into mad science, experimental mode.

I cut the top off the ugly, marred bottom segment of my Opuntia and rooted it - It's now its own 4-segment Opuntia and growing very nicely. I sliced a 1/4 inch off the remaining bottom section and took two of the pups off the Moon Cactus and grafted them onto this segment of the Opuntia (aka Tuna/Nopal - the one that grows cactus pears). These grafted very well and are growing, have increased in orange color and are doing spectacularly.

I took another pup off the Moon Cactus and grafted it onto another baby Opuntia. This also grafted very well. I now have one two-headed Opuntia and one baby single headed Opuntia graft. I can't wait to see what these do on Opuntia.

Now here's the really mad science part - I cut the 5" tall Hylocereus part of my original Moon Cactus straight across the center, grafting yet another pup onto the rooted piece of Hylocereus to duplicate a new Moon Cactus. I placed the cut top piece, containing the mother Moon Cactus and 6 attached pups on relatively dry (a little water) cactus mix. I'm waiting to see if this piece of Hylocereus will root. After three weeks, the mother Moon Cactus & pups look great but the Hylocereus has not rooted. The question is, will it.

I believe the Hylocereus is a hardy cactus and am hoping it will root when cut - We'll see. I did notice that there is a thick, woody center that looks like a stick/woody reed in the center at the bottom of this cut portion. It has not rotted or anything, so I'm keeping my fingers crossed.

Thanks again for the great post and keep your fingers (and eyes and toes) crossed for my little experiment.

Anonymous said...

Great blog, thanks! I wanted to let the fans of this 'unsung hero' know that I just purchased a 2.5 qt sized one at Home Depot in Chico, CA. They are from "Smart Planet; drought tolerant plants", in green plastic pots, for only $5.48! Hopefully all of the Home Depots are carrying them. Good luck to all!

Lou comptoo said...

I ran into that strange fruit in the supermarket and liked it. I went looking for a dragon fruit cactus. I bought one on line and planted it in 2011 about 2 years ago.
A week ago we noticed something growing from one of the limbs. Low and behold it was a flower and then a second one. What beautiful flowers and very large white in color. First one bloomed and 2 nights later the other,
I now hope that I may get 2 fruits in their place. I Wish I could post a picture to show you.

Taram0810 said...

If the lazy bum of a red ball on mine falls off accidentally (not bc it rotted or anything) can I graft a new one on the same plant? Also sometimes there's like 5+ mini colored balls sprouting off the main large one. Can I use one of them to graft? Thanks!!!

mr_subjunctive said...

Taram0810:

I haven't done any of this personally, but my guesses would be that yes, you could graft a new top onto the same base, though you would need to re-cut the base, and yes, you can graft with one of the offsets from the top.

The only caution I would have about using one of the offsets would be that you'll need to remember that if the plant on top is too small when you make the graft, it's liable to pull free of the base as it gets bigger while the base stays the same size. Ideally you'd want to re-graft with an offset that's about the same size as the original top was.