So, okay, dear readers, I haven't posted the Philodendron hederaceum profile just yet, even though it's been in the sidebar as the next profile for, like, weeks now. There are lots of good reasons for this, which are not likely to be that interesting to you but are totally valid. (
I'm still working on it. It'll happen soonish. It's done, as of 16 March 2009.)
I've decided to take this piece out of the profile and give it its own post, because it'll shorten the actual profile and because it's also a small, manageable subject that comes up a lot. And the subject is, how do you tell the difference between a pothos (Epipremnum aureum) and heart-leaf philodendron (Philodendron hederaceum)?
So here we go, a trivial problem solved in seven easy steps (though most of the time you'll only need one or two of these to be able to make the call: #s 2, 6, and 7 are fairly decisive):
1. If the new leaves are glossy, the plant is probably an Epipremnum. If new leaves are matte, the plant is probably a Philodendron.
2. If the new leaves are folded along the midrib, the plant is probably an Epipremnum. Philodendron leaves are pretty much flat for the leaf's entire life.
3. If there is variegation in the leaves, Epipremnum leaves will have finer details, including tiny dots and streaks. Philodendron variegation has cleaner lines and is less intricate. (This has become less decisive since I first wrote this post: it's still generally true, but I have found a speckly Philodendron, which is still very uncommon in retail as far as I've seen, probably because the variegation isn't very stable and tends to disappear, and a non-speckly Epipremnum by the name of 'N'Joy,' which is getting to be fairly common in stores. I think we'll be seeing new non-speckly Epipremnums in the future, from what I've seen on-line from plant breeders. So don't rely too heavily on this one.)
4. There is also a subtle difference in the leaf tips: Philodendrons have a more exaggerated "drip tip," an extension of the end of the leaf which must serve some purpose, but which has never really been satisfactorily explained to me. Something about enabling the leaves to shed water more quickly or something. Epipremnums (and most other members of the Araceae, actually) also have these, but they're less prominent.
5. If the new growth is the same color as the old, or only slightly lighter, it's an Epipremnum. New Philodendron hederaceum1 leaves tend to be reddish, especially if the plant is in good light. I.e., the plain green variety starts out slightly olive; the yellow variety starts out reddish or orangish, etc.
6. If the petioles2 are grooved, it's an Epipremnum. Petioles which are smooth along their whole length belong to Philodendron.
7. If developing leaves are protected by a sheath, which later dries up and falls off, you have a Philodendron. If there's no sheath, it's an Epipremnum.
Does it actually matter which is which? Well, yes and no. Both plants are pretty long-suffering, vining plants with heart-shaped leaves.3 In general, if conditions are acceptable to grow one, the other would also grow there, but in some situations one or the other is preferable: Epipremnum handles neglect, low light, and dry heat better, for example. Philodendron has a slight edge when it comes to propagation, cooler temperatures,4 and overwatering. Both would prefer more light than they usually end up getting, though Philodendron, at least, will sunburn if the light is too bright: I've never known Epipremnum to burn, but the leaves get black tips and margins if it's too wet or if there's root damage (among other reasons).
There are also certain long-term differences in appearance, and if you can convince them to climb something, there will be even bigger differences in appearance: Philodendron leaves develop a velvety texture (eventually), and Epipremnum leaves get Monstera-like perforations.
I feel like being able to call things by their actual names should be a good enough reason to learn the difference all by itself, but then, I'm pedantic that way sometimes.
Photo credits: all mine.
1 I have to specify hederaceum because this is specific to it. Among Philodendrons in general, new growth is frequently redder or lighter, but not necessarily.
2 Petiole is a botany vocabulary word for the stem-like structure connecting the leaf to the actual main stem. They could have just called it "stem," but then people would have to spend a lot of time specifying which stem, over and over, and there'd be confusion, cats lying with dogs, and all that, so a new word was invented for this particular kind of stem. This is how jargon gets born, and it doesn't have to be any more intimidating to you than you want it to be.
3 (or kinda heart-shaped: with Epipremnum, the smaller leaves are usually more or less oval or lens-shaped, and they'll only appear to be heart-shaped from certain angles because the leaf is folded down the midvein. Very large, mature Epipremnum leaves are heart-shaped, but those are uncommon indoors.)
4 Though neither plant particularly likes cooler temperatures, pothos seems to be the only one that actually starts to freak out if it gets too cold: the Philodendron just sort of stops growing for a while. Pothos is especially touchy, in my experience, about getting watered with cold water, which is a problem every winter at work because we can't control the water temperature. So it alternates between drought and freezing all winter long, and then starts to recover when the cold water out of the tap warms up. The Philodendrons probably don't like the cold either, but they're less vocal about it.