Saturday, February 16, 2008

Schoolgirl of the Underworld (Saxifraga stolonifera)

I never really gave much thought to Saxifraga stolonifera until I started working in the greenhouse. I didn't think it was a bad plant, I didn't think it was a good plant: it was one of those plants out there that other people, for some mysterious reason, found compelling and interesting, but that my eyes always skipped right past. If pressed, I might have gone as far as "cute, but not my thing."

So it was, and so it would have remained, if not for my job, where I was occasionally directly confronted with them, growing in the soil under the tables at work. This happens cause the tables are just big metal grids, basically, and things fall through the grids, especially things that have grown through the grids, which get ripped off when the plant gets picked up and moved elsewhere. Saxifraga stolonifera pretty much owns the greenhouse underworld for a lot of the year; we have a few species of weeds around as well, and the occasional other ornamental,1 but the only ornamental plant that shows up routinely is this one.

There's both too much, and not enough, information out there on Saxifraga stolonifera. A decent googling will turn up a number of sites related to outdoor gardening (including Martha Stewart her own bad self2), but none of the information in question is really relevant to growing one indoors. (Though I do now know that they're supposed to be hardy from zone 6 or 7 up to zone 10: they can and do come back from freezes.) There are also, if you dig deep enough, a lot of sites talking about specific named cultivars, but these rarely have pictures, and even when there are pictures, the pictures are usually of a whole bed of plants, so you just see a big pile of foliage and there's no close-up to show how this particular pile of foliage is different from any other.

Which maybe that's not important. I don't know. Like Pilea cadierei and Plectranthus verticillatus, this isn't a terribly common plant in stores, at least not that I've ever noticed before, but then, also like those two plants, it's easy enough to propagate that nobody should really ever have to buy it in the first place.

In any case. It's grown on me, just by virtue of seeing it around all the time. I dug five plantlets up off the floor and brought them home with me, and they've turned out to be nice, though five is, realistically, probably more than a person actually needs. I'm not sure what the official line on indoor care is, but mine have been fine so far in filtered sun, fairly cool temperatures, and all kinds of watering. (One plant was getting dripped on by a leaky plant saucer above it, so it was very wet for a very long period – it did fine. Another one didn't get water for a long time and also did just peachy.) This is essentially also the scenario on the greenhouse floor, though the greenhouse floor tends to be bright, cold, and wet, not bright, cold, and dry. Light seems to be the biggest issue: they don't need full sun, necessarily, but it does need to be a bright spot if you're growing them indoors.

Propagation is about the easiest thing imaginable: the plants produce runners (which is the reason for the "strawberry" part of "strawberry begonia") with baby plants on them, much like Chlorophytum comosum, and these plantlets will root easily in soil given half a chance to do so. Plantlets can be left to hang over the edge of the pot, if that's a look you're into; a few will inevitably root in the same pot as the mother plant, leading to a fuller plant after a while, though I kind of dig the one-pot, one-plant look, too. A newly-rooted plantlet will begin producing its own plantlets in about three to six months: larger plantlets, or plantlets in good conditions (sunny, warm), will go faster.

Unless watched fairly carefully, plantlets will land in neighboring pots, creating spontaneous dish gardens. This may or may not be something you want to see.

Pests don't seem to be a huge issue, though we had a small mealybug problem on one of the plants at work. I never was sure about the mealybugs: there was a big white fluffy mass in one spot, but it was only in that one spot, and it might have been a clutch of spider eggs or something. I know for a lot of you, spider eggs wouldn't really be an improvement, but for the plant, that's far preferable to mealybugs. I don't remember what I actually did to treat the plant, if anything, beyond cutting out the leaves with the white fluffy stuff on them.

There are flowers, though I have yet to see them in person: thus far I've only seen buds, and then only recently. The actual flowers are oddly shaped, with two long petals and three short ones, and they're not especially striking on their own, though they're pretty in large masses, I suppose.

The association has formed in my head that "strawberry begonia" (or, occasionally, "strawberry geranium," though it's not a strawberry, begonia, or geranium) is somehow related to the character "Strawberry Shortcake," the oddly dessert-themed dolls for little girls from the late 70s into the mid-80s, which seems like a hell of an odd product to be selling when people were first cluing in to the phenomenon of adolescent and pre-adolescent eating disorders, by the way. The plant and the doll aren't actually related, obviously, but they do both have a certain rounded pink fuzziness in common that locked them together in my head. I still think, awwww, adorable when I see a Saxifraga stolonifera on the greenhouse floor, but now that I've tried keeping one myself, I do at least know that it's not just another cute face. It's a cute face bent on conquering the greenhouse floor. Which is a very different thing.


Photo credits: greenhouse floor, budded plant, extreme close-up: me.
Individual flower, mass of flowers: Stan Shebs, at the Wikipedia entry for Saxifraga stolonifera.

1 Other species I've seen hanging out under the tables: a Plectranthus coleoides 'Heigh Ho, Silver' that grew from a piece that broke off of a hanging basket and managed to fall in the right spot; a couple bears-paw ferns (sorry, don't know the botanical name) that I deliberately planted, because they were in another plant's pot, but too small to sell on their own; a Pilea 'Silver Tree,' lots and lots of Bryophyllum daigremontianum, Crassula ovata, and Albuca bracteata (pregnant onion; more commonly known as Ornithogalum bracteatum or O. longibracteatum) that have grown from leaves or bulblets; one Tradescantia zebrina that I encourage to grow because it's a handy source of cuttings; a Calathea of unknown species (it was very tiny); one tiny Boston fern (Nephrolepis exaltata), a Senecio macroglossus, occasional Alternanthera dentatas, and then lots and lots of three different genuine outdoor-type weeds: Oxalis cornicularis, which drives me crazy because it's impossible to pull up, one that might be yellow rocket (Barbarea vulgaris), which is impossible to keep under control, and a third which may be velvetleaf or something closely related. Exact indentification is difficult, since for obvious reasons we try to prevent them from reaching maturity. These three weeds are the real owners of the greenhouse underworld, but they're also almost exclusively found around the edges, where the light is better: Saxifraga stolonifera can and does pop up pretty much anywhere.
2 Martha could use a staff grammarian, by the way. Somebody is heavily addicted to commas: "Mist and groom plants occasionally, remove yellowed foliage. Repot in spring if pot bound, plants may be divided if desired." Both of those sentences contain a comma splice. There are also some apostrophes on that page which are painfully out of place. It's not such a big deal, but, you know – I expect better punctuation from Martha. Martha: if you're reading this, please know that I work cheap, and I can spot a misused semicolon at 500 yards. Have your people call my people.

Friday, February 15, 2008

Random plant event: Philodendron gloriosum for Valentines Day

Extremely slow computer today, plus I'm having issues with my on-line connection and/or Blogger, so I'm sorry for the brevity, but.

The husband got me this for Valentines Day, because I'd commented on it before when we've seen it in the supermarket previously. I don't exactly know how to take care of it (part of why I hadn't bought it for myself already), but when I did a search for it yesterday evening I didn't come up with anything that sounded too scary. Let me know, if you have experience with this, but in the meantime I'm going to assume it's more or less just like any other vining-type Philodendron and treat it accordingly.

I also don't know why our grocery store can get these but we can't get them where I work; it's not the only plant like that (Ardisia elliptica is another that they can get but we can't), but it seems odd that this, the only plant of its kind I've ever seen in my life, would just be hanging out in the grocery store, and more incredible still, that it would be there without getting sold for a month or better without anybody buying it.

So it was a nice surprise.

Thursday, February 14, 2008

Random plant event: Codiaeum variegatum flowers

I had intended a plant profile to go up today, not because it was Valentine's-appropriate but just because one was due, but I'm having some trouble with finding enough information and having time to write it down. Among other things, I'm working five days per week now, instead of the four it's been since beginning the blog, and my own personal plants are beginning to need more care now that they realize spring is starting. So . . . sorry. From here until about May, at least, the profiles are going to be less frequent, and I may occasionally have to skip a day's post for one reason or another. It's possible that the slow-down will continue until September or October.

But anyway. I noticed this a few days ago. One of the Codiaeum variegatums in the greenhouse had flowered sometime within the first couple months after I started work, and I missed the whole thing, only noticing after it was all over. I wasn't expecting to see it happen again for another four months at least, if ever, but apparently they're not as seasonal or shy as I thought. This hasn't even really started to open yet, but I'll be watching. Sooner or later it will have to.

The really funny part of this is, the crotons have been hating life this last few months. I mean, they're starting to pull out of it, but some of them never get dry, some of them never get wet, all of them are too cold most of the time, there's been an intermittent spider mite problem, and I've been picking up dead leaves for months now. So this could be an act of desperation, one of those I have to reproduce before I die kind of things. I suppose we'll see.

Tuesday, February 12, 2008


I'm constantly reminded of this song lately. I don't know if it's actually good advice, but lately it seems like it must be. And yes, those are all the lyrics. It's a very short song.

Buy more stock in roses
Millionaires will always woo
Don't be shocked if roses
Make a millionaire of you

-"Roses," by Magnetic Fields (Stephin Merritt),
on the CD 69 Love Songs Vol. 2

Disclaimer: advice does not apply in Saudi Arabia.

The Iowa Pesticide Exams: I'm Not Feeling Any Safer

Road trip!1

I spent about half of my day yesterday taking the Iowa pesticide exams so I could be certified to be the guy who sets up the pesticide sprayer in the greenhouse, which is not a huge job necessarily but it's one that is supposed to be mine, and which I haven't been doing since I started, since I don't have the license to do it.

In Iowa, the tests are set up such that you have to take a core test of 50 questions (40 to pass), and then you have to take separate 35-question tests (28 to pass) to certify you for specific types of spraying.

I did just fine on the core test (46/50), and then missed the greenhouse test by four questions, one of which doesn't count, a lot of which had nothing to do with whether I knew the material or not and everything to do with the tests being written really sloppily. E.g., one of the questions I missed was asking about bugs that were resistant to pesticides, but they phrased it in such a way that it was really ambiguous whether they were asking, "Which of these pests is resistant to pesticides in general?" or "Which of these pests quickly becomes resistant to certain classes of pesticide?" The choices were like, mealybugs, spider mites, thrips, and fungus. The booklet one is supposed to study for the test had made a point of mentioning that mealybugs are resistant in general, because of the water-repellent waxy coating (which we've talked about before), but it had also emphasized that spider mites were difficult to get rid of completely because they quickly developed resistance to new pesticides. I went with the mealybugs, then considered changing it to spider mites, but talked myself out of it (everybody knows you're not supposed to second-guess yourself on standardized tests like this), and they wanted spider mites. So I get the question "wrong" not because I don't know the answer, but because they can't write the question specifically enough for me to determine which question they're even asking. This is frustrating.

There was another question like that, that was ambiguous between two answers, and I had the right one and then switched to the wrong one at the last minute. Don't remember what that one was about, though.

There was also one question where all of the answer options were wrong. And I don't mean just a little wrong, I mean, really wrong. It was something like, "Which of the following statements is ACCURATE about the greenhouse whitefly?" and then the choices were:

a. something really dumb that I don't remember
b. has black, sticky droppings
c. feeds between the upper and lower surfaces of a leaf
d. produces honeydew

Leaving aside my pedantic irritation that none of those are statements, they're sentence fragments, there's also not a true one among the bunch. For B, they're clearly hoping you'll get whitefly confused with caterpillars, for C, they're hoping you'll be confused with leafminers, for D, they're hoping you'll be confusing whitefly with scale, aphids, or mealybugs. But they neglected to put a right answer in. I went with B, figuring, well, I never really paid all that much attention to whitefly droppings before, so maybe they could be black and sticky, who knows, and the answer they wanted was D, produces honeydew. And I'm like, come on, State of Iowa, you're killing me here. So I went and talked to the guy administering the test, and he agreed with me that no, that was wrong, they don't produce honeydew, and none of those answers were correct, and so if I took the test from him again (which it looks like I'm likely to: I think the state only has just so many people doing this at any given time), he'd just give me that one, if it was the difference between passing and failing.

And it's not that terrible of a thing; there's no fee for the test (surprisingly) and the waiting period after you fail is apparently about 18 hours: I could go to Donnellson today and take the test again, but Donnellson is more than halfway across the state and anyway they need me to work 'cause it's Valentine's Week and there are rose bouquets to be assembled. Realistically, my next shot is next Monday, in West Branch.

But -- this doesn't make me feel safe at all. If you can just take the test over and over until you pass, it means you don't have to even read the book. You don't have to know anything: just show up and take the test as often as you can until you happen on a winning combination. And, hell, they let you see which ones you got wrong, and what the right answers were, right after you take it, so sooner or later, you'd see all the test questions anyway.

(public domain)

I dunno. For some reason, I was expecting that there'd be bigger obstacles than this. I mean, this is poison we're talking about: I don't really want it in the hands of any yahoo who was just stubborn enough to show up and take the test until they passed.

So I wind up disappointed twice: I'm disappointed because it's too hard, and disappointed because it's too easy. Also I'd like to take this opportunity to offer my services to the State of Iowa as a test-question writer: I could write questions that weren't ambiguous, where "statements" were actually statements and "questions" were actually questions and where one and only one of the choices for each question was actually correct. Just in case anybody's interested.

Not that I expect Mississippi is going to be mocking our pesticide-exam syntax or anything. But still. I give it two and a half stars. Missable.


1Iowa isn't all as flat as it looks in this picture, despite what you may have heard.

Monday, February 11, 2008

Teacher (Sansevieria trifasciata), Part II

(See Part I here, if you haven't already read it. Also while you're there, check out the comments. Some interesting stuff on Sansevieria's namesake.)

Okay, when we left off before, I was dangling in front of you the promise of understanding why variegated specimens of Sansevieria trifasciata revert to the plain varieties when you try to grow them from leaf sections, but not when grown from division. We'll get there, but you should bring some water with you, and maybe go to the bathroom – it's going to be a long trip, and we won't have time for a lot of stops.

Sansevieria trifasciata, NOID similar to 'Golden Hahnii'

First important concept: many variegated plants are chimeras (ki-MARE-uh). In the broadest use of the word, this means that not all cells in the plant contain identical genetic information. This is not all that uncommon, actually, in people, animals, or plants: if you are a woman who has had a baby, there are probably some of your child's cells running around in your body right now, however long ago it's been since you gave birth. Such cells have been implicated as maybe being involved in disorders like scleroderma, but at the same time may also protect against some kinds of cancer (ref 1, ref 2). The same also applies if you've ever had a blood transfusion: you're not guaranteed to have some of your donor's cells still roaming your body, but (especially with large or repeated transfusions) you may still have a small percentage of white blood cells which are not, genetically, your own. A few people out there initially develop in the womb as a fraternal twin, and "absorbed" their twin early in development, with the result that they contain two types of cells: those from one twin and those from the other. This isn't thought to be all that common, but of course how would you know? Previous cases have come to light as the result of paternity tests (in one notable case, a paternity test revealed that the "mother" of a child was not the mother of the child, which you can bet caused a lot of anguish for all involved) or in tests for potential tissue donors or recipients. I predict that we'll find out this is a lot more common than people think, whenever genetic tests are cheap enough to be routine.

Oh, and – obviously, if you absorb your identical twin at some point, no one will ever be able to tell by genetic testing, because, duh, identical. So there's no telling how often that happens. (We know it happens at least once in a while, because sometimes, er, the twin is only incompletely absorbed, and people discover tumors later in life that have teeth and fingernails in them, or weird shit like that. I'm not kidding. It happens.)

It gets waaaaaay weirder than that (Anglerfish! Mosaics! Hermaphroditism!), but I'm just trying to establish the concept here, so let's move on.

Botanical chimeras are easier to believe. Generally, what happens is that a cell in the developing tip of a plant mutates in such a way that it can no longer produce chlorophyll or some other plant pigment, or it still produces it but at a much slower rate, and then as the cells continue to divide and reproduce, this leads to some large sections of the plant which are a different color than the rest of the plant.1 There are three basic layers of cells in the developing growing tip, which are whimsically called, from outside to inside: I, II, and III (those wacky biologists!). Each of these give rise to different parts of the developing leaf. Mutations in I affect the very outermost edge of the leaf, like, say, the parts of 'Black Gold' which are yellow in this picture:

Sansevieria trifasciata 'Black Gold.'

Mutations in III affect the center of the leaf, and mutations in II affect a section in between the two. In the three simplistic drawings of leaves below, which are loosely modeled after Chlorophytum comosum 'Vittatum,' Dracaena deremensis 'Warneckei,' Sansevieria trifasciata 'Laurentii,' and Dracaena deremensis 'Lemon-Lime,' we can see examples where each layer of cells, in turn, lacks chlorophyll-producing cells. The Chlorophytum-modeled leaf lacks chlorophyll in layer III, the Dracaena 'Warneckei'-modeled leaf lacks it in layer II, and the Sansevieria-modeled leaf lacks it in layer I (though it still expresses a yellow pigment of some kind). In the Dracaena 'Lemon-Lime' leaf, we have a double mutation: layer II expresses no pigment, and layer I expresses only a little chlorophyll, along with a yellow pigment of some kind.

But wait! It gets so much better, because this explains all kinds of crazy stuff. For example, we can now gain a little bit deeper insight into what was going on with the Dracaena deremensis 'Warneckei' I reported about a long time ago: obviously, when the stem was cut and the plant had to resprout, a mutated cell in layer III that couldn't make chlorophyll was allowed to spread and be expressed in that particular growing tip, along with the original 'Warneckei' mutation that produced a chlorophyll-less layer II. The result: bigger white patch in the middle.

The actual plant. Ah, memories. . . .

You can play this game at home: which layers have to be mutated to form the reverse-variegated Chlorophytum comosum? What about turning Dracaena fragrans into D. fragrans 'Massangeana?' Does Tradescantia zebrina make more sense now, in some odd way?

Now for the disclaimers.

We need to note here that expression or lack of expression is not always as clean and precise as I've made it out to be. Dracaena sanderiana, for example, tends to have a single band of pure white or cream color along the outside edge of the leaf (the layer I cells), but then lighter and darker stripes through the rest of the leaf. My guess is that the lighter stripes are spots where cells descended from both layers I and II are laying on top of one another, so the resulting color is lighter than II but darker than I, and then the layer-III cells in the middle of the leaves are normal. But I could be wrong.

Also, all of the plants that I have discussed so far are monocots. Monocots typically have one initial seed leaf (which is where the name comes from: the opposing group, the dicots, have two: mono = "one" and di = "two"), flower parts occur in multiples of three (lilies and tulips being particularly vivid six-petaled examples of this), and leaf veins are typically parallel from base to tip, instead of branching out from a midvein like in dicots. The above discussion of variegation mostly applies to both monocots and dicots, though with dicots, layer I usually only forms the colorless epidermis of the leaf, so it would make no visible difference if those cells could produce chlorophyll or not, because you don't normally see any color in them anyway. Also it's easier to tell what's going on when all of the color variation happens along parallel straight lines, as it does with monocots. Dicots tend to have uneven boundaries between layers II and III, and so you get variegation that's either dark with light edges, or light with dark edges,

(L-R) Hoya carnosa 'Krimson Queen' and 'Exotica'

depending on which layer was affected by the original mutation.2

Wheeeee! Are we having fun yet?

So let's get to the original question, then: why, with all this crazy layering going on, can you keep the variegation in a Sansevieria trifasciata 'Laurentii' when you're propagating by division of a rhizome, but not when you're propagating from a leaf section? After all, there are yellow and green cells to begin with in both cases: why can't they just stay together?

The reason is,


A plantlet from division retains the same overall organization as the original growing tip: all three layers of its cells will, at some point, resume growing and dividing as though nothing had happened, and the descendants of green cells will be green, and the descendants of yellow cells will be yellow. There's nothing, of course, to completely rule out a new mutation springing up at some point down the road, but mostly it's going to keep going like it's been going already.

A plantlet from a leaf cutting has all kinds of obstacles to get over at first, though. Like, for one thing, it has to organize a new growing tip somewhere. First step in that process? Turning a cell into the new growing tip.

Now, I don't know how the cell decides which cell to start with, but there are really only three things that could happen from this point.

1) A layer I cell, in the yellow leaf edge, is selected as the new start point. All three layers in the new plantlet are then going to be cloned from this starting cell, and, consequently, all three layers in the new plantlet are going to share the mutation which is preventing the cells from producing chlorophyll. The new plant will have trouble making its own energy, and will be limited by the amount that the original leaf cutting can produce. When the original leaf cutting dies of old age, or when the original cutting's ability to produce food is outpaced by the demands from the new plantlet, which has got to happen sooner or later, the whole shebang dies, and it all ends with no new plantlets.

2) A layer II or III cell, which does not have the mutation preventing chlorophyll production, is selected as the new start point. All subsequent cells, in all layers, are descended from this one and are therefore capable of producing chlorophyll. This means that all three layers of cells will be green, and consequently the whole plant is green.

3) The new shoot begins with any cell, and at just the right moment, a mutation happens. A yellow cell gets the right reverse mutation to enable chlorophyll production, and we have a new cultivar, or a plant that would have been all-green gets chlorophyll production knocked out in one of the founding cells and some part of the new plant gets to be yellow, possibly resulting in a new cultivar. Either situation is a huge long shot: if you did nothing but plant Sansevieria leaf sections for the rest of your life, it's possible that you might see such a mutation occur . . . aaaaaand it's possible that you wouldn't. Or, I guess, technically one of your assistants would be the one to see it, not you, because you're not doing anything but planting leaf sections for the rest of your life. Like I said.

So that's why the variegation doesn't continue from a leaf section: one way the whole thing dies, one way it's all-green, and once every few million times, there's a new mutation that saves the whole thing but that's so rare that you'd be foolish to count on it. A similar mechanism is at work, I believe, when Hoya carnosa 'Krimson Queen' produces an a vine consisting of nothing but white leaves, though I claim no particular understanding of how Hoya plants decide to branch.

And so. Gosh, this has been a fun profile to write. I went off-track a number of times, I piled on the random details, the word count is outrageous compared to previous profiles, but I loved that moment where I understood how this type of variegation works, where it clicked, and I started putting together, oh, this is what was going on with the 'Warneckei' sport, and this is why you don't see leaves with this kind of coloration, and oh my god, why have I never noticed how similar these all are to one another before?

The structure beneath the beauty, the mechanics of it, has its own sort of beauty. I've really never understood the people who complain about how, you know, when you find out that a rainbow is just a bunch of refracted light it ruins the magic of the experience. It takes the mystery out of it, or whatever. I've always thought it made it better to have that kind of insight into the experience, to see the pieces fit together, to see the connections. Not that there's not also something to be said for just letting the pure sensory experience of a new thing (seeing Saturn in a telescope, meeting a new houseplant for the first time, hearing a piece of music that immediately becomes your favorite song ever, learning a new word) happen on its own, but if you never connect it to anything else you know, if it never does anything to flesh out your understanding of the world in general, then you've missed an opportunity to be impressed a second time by the same thing.

This is the sort of thing I love about science: it's not just that it has practical, technological applications, though those are often nice. What I like is that if you dig down deep enough, and see how it all works, there are almost always connections to be made to something you'd never have thought was related: if you're doing it right, you can almost always make familiar things strange, and vice-versa. It's the closest I ever get to feeling like a kid: that whoa moment when it clicks for me that the Earth's axis is tilted, or those dinosaur bones used to be an animal, or matter is made of atoms, or whatever.

Sansevieria trifasciata 'Hahnii'

This post is not the be-all and end-all of variegation. It works well for certain kinds of variegated plants, but you may have noticed that I didn't even try to explain where the horizontal bands of darker green come from, on Sansevieria trifasciata, so it's obviously incomplete.

It also doesn't work as an explanation for a lot of variegated plants. We need something else for Dieffenbachia, for example. And this isn't helpful with Aspidistra lurida 'Milky Way,' either, or many, many other variegates. But, you know, baby steps.


Photo credits: all are my own except for the Dracaena sanderiana picture, which was anonymously donated.

References: A lot of this post came from this site, which is actually sort of obnoxiously overcomplicated and jargony for my money, but on the plus side, it's overcomplicated and jargony enough that it sounds authoritative to me. A related post is here. The site which got me started on this whole thing, by throwing the previously-unheard of term "periclinal chimera" at me, leading me to google the term and then try to understand it, is here.

1 There are other types of botanical chimerism. Grafted plants, for example, are chimeric, and these are even more extreme than the ones we're talking about: they don't even necessarily have to be from the same species. We kind of covered this in Hylocereus undatus.
2 The uneven-edges thing is, as best as I can figure out, because some dicots have leaves which are arranged like a stack of pancakes. Each pancake in the stack has the same I-II-III organization we're talking about, but the pancakes are not identical. So, any given spot on the leaf may have no layers of pigment, one layer, two layers, etc., which results in blotches of color which get generally darker or lighter as you move from the center of the leaf to the outside, but don't do so in any kind of smooth way. It may help to look back at some of the pictures in this post, particularly Ficus benjamina 'Spearmint,' which appears to have this kind of structure. Citrus limon 'Pink Lemonade,' Codiaeum variegatum 'Andrew,' and Peperomia clusiifolia all also have leaves that look like this. They actually all look more related to one another than they do to their actual relatives.