(This is part 4 of the Wizard of Oz series of plant profiles.)
I really like Pachypodiums. I like the look of them; I like that they're not unreasonably difficult to care for; I like that I got mine outrageously cheap.1 I even like the thorns -- kinda. They certainly make it look more intense and dangerous, and along with the silvery gray (dare I say tin?) color of the trunk, they give it a sort of industrial / Alien / sculptural look. I mean, if you had never seen one before, you could maybe believe it as some kind of plant from the future, some kind of machine-plant combination made from nanobots! by space aliens! or whatever.
However. I spend a lot of my time at work moving plants from one place to another. I try not to move the Pachypodiums so much, but I still have to move things that are near them, and, well, there is only one plant that's resulted in more lost time with the tweezers, trying to pull thorns/spines out of my body.2 The Pachypodiums also like to team up with the Agaves so that one lightly pokes me from one side, causing my hand to jerk away from it involuntarily into the other plant: whether I jerk into the Pachypodium or into the Agave, I wind up getting stabbed deeply, and the Pachypodium spines like to break off in my skin, so then I have to take my hand apart to remove the broken-off piece.
If they only had a heart. Or hearts, plural, I guess. You know?
But even so. In the course of poking around the web looking for interesting stuff about the plant, I found a lot of people saying things like, "This is my favorite plant." Which is pretty high praise. I wouldn't go that far, personally, but it's been kind of delightfully unproblematic, and as we know from some of the other profiles, it's not like I necessarily object to being surrounded by plants with thorns, spines, sharp edges, potentially deadly poisons, or whatever. If that's the most dangerous kind of thrill-seeking I do, I should be able to live a long and healthy life anyway.
The common name for these, "Madagascar palm," is half correct. They are from Madagascar. Pachypodiums are not palms, however, even though they look a little (a very little, in my opinion) like one. Besides the 25ish3 described Pachypodium species, the family Apocynaceae includes several other ornamentals like Nerium oleander (oleander), Adenium obesum (desert rose), which I'll be profiling shortly, Mandevilla/Dipladenia,4 Vinca, Catharanthus (also - incorrectly - called Vinca), and Plumeria (frangipani). Of these, few are grown indoors, though I've heard of Adenium, Nerium, and Plumeria being used as houseplants to some degree or another.5 (Of course, with Plumeria, pretty much the only person I know to attempt it indoors is WCW, who is always pushing the envelope on what range of species might be called "houseplants.")
Pachypodium's closest relatives would be Mandevilla, Adenium, and Nerium, which are all not only in the same family but are also in the same subfamily. The family resemblance is not particularly obvious from the various growth habits: it's not a vine like Mandevilla or a dense shrub like Nerium, and although young plants resemble a spiny Adenium, the similarities fade with age as the plant's trunk elongates. The stems of Mandevilla, Adenium and Plumeria do all, at some point in the plant's life, have the same gray-metallic sheen to them. Also the flowers are fairly similar in all the cultivated plants: five-petaled, usually red, pink, or white with a yellow center, and often though not always trumpet-shaped. So the family resemblance is there; you just have to look for it a little.
Pachypodiums flower too, but it's uncommon, and plants have to be fairly large, apparently, before it happens. It's not likely to happen indoors. I'm told the flowers are white, trumpet-shaped, and fragrant. There are pictures of varying quality at these four sites: (1) (2) (3) (4). I especially recommend #4.
Another common feature of the Apocynaceae is poison.6 All parts of Pachypodiums are poisonous, though I've never had any reactions as extreme as the one described here, which describes pain, numbness and swelling as the result of being stabbed by a thorn. I've heard rumors that the entire plant may not be poisonous: plantzafrica.com claims that the pith at the center of P. geayi can be strained through a cloth to yield a really unpleasant-sounding but technically edible sap. (Don't try this yourself, obviously.) I didn't see this confirmed anywhere else, though, so I'm kind of still skeptical about it being true.
Also unconfirmed: Plantzafrica.com also claims that certain rural African peoples use P. geayi as a makeshift beehive, after hollowing it out, though there are no details about how this is done or why it would be necessary. Nice bit of coincidence: in the movie, the Wicked Witch of the West threatens to turn the Tin Woodsman into a beehive.
But I'm digressing.
P. geayi and P. lamerei are, as best as I can tell, the two most commonly grown indoor species, and not particularly easy to tell apart because there aren't a lot of pictures of the two side-by-side around to compare to. Most Pachypodiums in the retail horticulture world are P. lamerei: the main way to tell it apart from P. geayi is that geayi has small hairs on the leaves, particularly on the underside, and the leaves tend to be longer, darker, and bluer in color than on lamerei. The absence of hairs doesn't necessarily mean you have lamerei (sometimes geayi doesn't have the hairs, especially on young plants), but if hairs are present, then it probably is geayi. I thought for a very long time that my plant was probably geayi, then was informed by a PATSP reader that no, I probably had lamerei like everybody else.
Those websites expressing an opinion said that lamerei is the easier of the two to grow.
These can do very well indoors, though like a lot of plants, they do benefit from time outdoors if you can swing it for them.7, 8
LIGHT: The more, the better, within reason. These are best in a bright, large, unobstructed south window. They might get by in an east or west, but I make no promises. Haven't tried it, don't intend to. My own plant is in a south window but has to compete with a lot of other plants, and gets moved around a lot, so its situation is probably best described as partly-filtered sun, and this is apparently acceptable.
WATERING: This is a little bit tricky. During the winter, they go semi-dormant and need very little. During the summer, they need to be watered much more often. How much is "very little?" How frequently is "much more often?" Well. During the summer, the plant is relatively flexible, and it's not a big deal to water when the soil is dry to about half the depth of the pot. During the winter, aim for watering a couple days after the soil gets completely dry. (The thick trunk stores water. It'll be okay.) During the spring and fall, letting it go almost but not completely dry is good. Watering too much will result in leaves yellowing and dropping. Watering way too much will result in rot. The best defense against overwatering, if you're worried that you just won't be able to help yourself, is to use a clay pot and soil with really excellent drainage. Underwatering is really hard to do, but leaves will turn crispy and drop, and I'm guessing the trunk will also shrivel as the plant uses up the water it's stored. The shriveling may or may not actually be noticeable.
HUMIDITY: They don't care.
TEMPERATURE: Information about this on-line varies, and I don't have any personal experience with trying to see how cold they'll let me get. The most conservative range, from what I see, is 50-100ºF (10-37ºC); a few sites say you might be able to go down to just above freezing, but I wouldn't try it. Our plants at work have, until recently, been along a wall in the greenhouse, where they get hot, dry air blown directly at them from underneath whenever the heater comes on. This has been a problem only insofar as the heat dries out the soil faster, and leaves me confused as to when I should water, which I have a tendency to overdo with the succulents anyway. But the heat itself is not the problem.
PESTS: I've never had a problem with pests on mine, or the ones at work. Rot can be a big problem, even on well-established plants, particularly if the plant has been injured. Mealybugs are not unheard of, and spider mites are a problem for everything else in the Apocynaceae, so I wouldn't be surprised by spider mites. None of these are particularly likely, persistent, or damaging, but they are contagious, so it's good to keep an eye out anyway.
PROPAGATION: Usually, Pachypodium are grown from seed, and different websites report different degrees of success getting the seeds to sprout. The seeds don't store well, and are best used as soon as possible. They are also somewhat slow to germinate (about a month?) and not necessarily all that easy to find in the first place. As plants will occasionally branch on their own, sometimes from the base, people do occasionally take cuttings, for which the procedure is more or less the same as for cacti or Euphorbias: cut off a piece (mind the sap! And the thorns!), let it callous and dry in a bright but sunless spot for a week or two, then plant it upright in soil with unbelievably good drainage and water very conservatively until there are signs of rooting. If your plant begins to rot, taking a cutting of a healthy part of the stem, if one exists, is your best bet at salvaging something.
GROOMING: Plants will usually shed leaves in the fall or winter, as they go dormant, though if you slow down watering properly, this is less likely: they don't have to drop leaves, necessarily. There shouldn't be a lot of leaves to clean up if your plant does defoliate, mostly because your average Pachypodium doesn't have all that many to begin with. The down side is that they're harder to clean up than your average dropped leaf, because of their tendency to wedge themselves between, or impale themselves on, the thorns.
FEEDING: More or less what you'd expect. Light to normal for spring and summer, slow down in fall, don't feed in winter.
There are no cultivars of Pachypodium as far as I can tell: if there are varieties grown for the color of their flowers or the variegation on their leaves, I couldn't find any. There are also no thornless varieties, at least not of these species (other Pachypodium species may be less extreme, with the thorns), though on older plants, the thorns sometimes get broken off, leaving a smooth patch. I did find some pictures of a cristate plant, which is satisfyingly different, and even freakier and more alien-looking, but also probably not available for sale.
According to the movie, one's "heart is not judged by how much you love, but by how much you are loved by others." This is really questionable logic (like the Wizard's other pronouncements, actually), but in this case, it kinda works. Spiny, complicated and poisonous though they are, people do love Pachypodiums. Myself included. Just, you know, tempered with a certain amount of respect. And fear.9
Photo credits: Tin Woodsman photo via shawnnacox.com. Pachypodium pictures are my own.