While looking over photos from my California desert trip this spring, I came upon this curious plant:
You can see most of the plant is dead (white branches), though there are two clumps of vigorous growth, shown up close here:
What’s going on here?
Answer Monday!
Castor Bean – Ricinis communis. Folks who make their living creating fabulous color displays for public gardens, municipalities, and commercial parks love ‘em. Civilian gardeners/plant geeks love ‘em. People who get their knickers in a twist about poisonous plants do not.
Pros: ridiculously rapid growth, huge leaves for that tropical look, tolerant of less-than-ideal conditions, cheap and easy to grow from seed, weird wild flowers and seed pods.
Cons: pretty darn poisonous. A few seeds (have seen figures from four to 20), chewed up to release the toxic protein ricin, will allegedly kill you. A Caster Bean seed looks like a really huge tick (head and all), which should be sufficiently repellent to anyone over ten years old. Pleh.
Beans with flowers. U.S. Botanic Garden, 2005, Washington D.C.
This topic arises because I was standing in our campus garden yesterday with said pot o’ poison (cultivar ‘Carmencita’, a red-leaf form), trying to find a place to plant it. Last summer, my department head noted them growing in front of our garden pavilion and asked that I kindly remove them. “They’re really poisonous, and kids will stick anything in their mouth, and I wouldn’t want my kids around them” (quoted best of my memory). He’s a wonderfully laid-back guy, so it struck me that he must really be concerned to bring it up. I teach Castor Bean in my Herbaceous Landscape Plants class for both the pros and the cons…heaven forbid a Hort graduate is unable to identify it, so I persuaded him into letting me keep it up if I removed the seed pods before they ripen. I’m not going to go into all the medicinal/industrial uses of castor oil (ick…I hope my generation was the last to have this foisted on us) nor the insidious uses of ricin – Google away if you’re interested.
We temperate-zone gardeners love anything tall and big-leaved to give vertical “oompf” to summer beds and container plantings. The tropical African native is considered an invasive plant throughout the subtropics; I’ve seen it in pastures and fence rows in far south Florida, the Cayman Islands and Dominican Republic. Apparently the cows and goats have learned to avoid it (natural selection?). I noticed it used en masse in the gorgeous beds lining the street in downtown St. Louis last summer, as well at several other public gardens I’ve visited over the past few years. So I’ll continue to use it in our garden’s palette of plants, but will remove the pods to keep everybody happy.
p.s. At the top of my summer reading list is Amy Stewart’s book “Wicked Plants”.
As Jason rightly guessed, this is a Schlumbergera species, specifically S. truncata, also known as the Thanksgiving cactus (which has toothed edges as shown). It’s related to the Christmas cactus (S. bridgesii – scalloped edges) and the Easter cactus (S. gaertneri, whose segments are three-sided rather than flattened). [Disclaimer: the nomenclature of this genus and its species is a mess. Even the university websites disagree on whether it’s Schlumbergera, Hatiora, or Rhipsalidopsis. Now you know why I am not a taxonomist.]
On to the more interesting question – those hairs. The green segments you see on these plants are not leaves, but flattened stems, called phylloclades (or cladodes). Phylloclade comes from the Latin word for leaf (phyllo-) and the Greek word for branch (-clade). These leaf-like branches are the primary photosynthetic organs for the plant.
So where, you may ask, are the leaves? That’s what those hairs are! And if you look at your Christmas/Easter/Thanksgiving cactus when it begins to set buds, you’ll see that the buds arise from the leaf axils – that point where the leaf joins the stem. This distinction is why these hairs are, morphologically, the true leaves of the plant.
Initially I was disappointed that no one answered the question…then Paul W. emailed to say that the post wasn’t accepting comments. We’re not sure why that happened, but Paul and perhaps many of you knew this was part of the flower of Sarracenia flava – the yellow pitcher plant:
I think this is a stunning flower whose floral structure promotes cross-pollination. Insects crawl in between the long yellow petals and the green "umbrella" to enter the flower and reach the pollen:
Before they reach the anthers, however, their backs rub up against the stigma, which are five tiny points at the "spokes" of the umbrella. Pollen already on their backs will be transferred to the stigma before new pollen is gathered, so that the chances of selfing are reduced:
So thanks, Paul, for being so persistant that you emailed me to supply the answer and alert me to the comment fail!
What is this "green disk of mystery?" It’s about 2" in diameter:
Answer on Monday – have a great weekend!
Recently I have been fascinated by the native wildflower field I planted last fall. Although I seeded it with the same mixture of seeds (mixed with sand to spread them evenly), you can see that we have clumps of different flowers throughout the area.
Figure 1. Descanso Gardens, California
The area where the wildflowers were planted had several 1-2 foot raised mounds; some were in the shape of keyholes. These were built with silty sand from a nearby seasonal stream that had some erosion problems in a rainy year.
Small differences between the temperature, moisture, light and soil on the different parts of each mound have favored different species of wildflowers. In one of the keyholes, I even found some miner’s lettuce (Claytonia perfoliata), a species I had not seeded that favors wetter areas. If I sampled for insects, I bet I might find a similar patchy distribution as well.
As an ecologist/biologist, I am really fascinated by the way that species diversity can be affected by topography, climate, moisture, and soils. As a gardener, I like that I could create conditions that favor different plants just by moving soil around. Plus I think that the waves of color are lovely as well.
Rachel Young is the head of the California Garden at Descanso Gardens, just outside Los Angeles. She has an MS degree in Ecology and Evolutionary biology from UCLA and lectures on various garden and horticulture related topics.
A few of you bravely hazarded guesses about this plant, and while it is a contorted specimen, it’s actually Ulmus glabra ‘Camperdownii’, otherwise known as Camperdown elm. Here’s a photo of a lovely example at Marymoor Park near Seattle:
As plant geeks already know, this odd tree was propagated from a mutant branch discovered on the Earl of Camperdown’s estate in Scotland in the 1800s. All Camperdown elms are grown from cuttings originating from this single tree grafted onto a Ulmus spp. rootstock which supplies the straight trunk.
Though these trees don’t get terribly tall, they can become quite broad and need space for their tiers of foliage. Like other contorted trees, the branches of old Camperdown elms can meet and fuse, as you can see in the photo from Friday. And while the tree produces scads of seeds (that’s what you see in the photo above – not leaves!), they are sterile.
On a recent spring day, I photographed this Medusa-like structure:
But rather than snakes, these are branches – and they are typical of a particular type of tree commonly used in landscapes. What is it?
Answer and fun facts on Monday!
Every once in awhile I become infatuated with some idea and can’t stop for looking for information on it. It usually starts when I want to find a good quote for a particular article or column that I’m writing and then ends up swallowing two or three days. Well, it happened to me again yesterday and spilled over into today. I’m currently finishing up a project with an old friend of mine from college who happens to be a political science professor at the University of North Carolina Charlotte. We’re looking at certain environmental issues and the stances taken on them by both the left and the right. Anyway, I wanted to make a point about biotechnology — that point being that when we graft two plants together we often get different chemicals in the plant which we grafted onto the rootstock than we would get if the plant were growing on its own roots. This is because many chemicals can be translocated from the roots to the leaves or even the fruit. Anyway, I quickly found a number of nice scientific articles to back up my statement, but I also found some other fascinating information about, of all things, tomatoes. There are many plants related to tomatoes that tomatoes can be grafted onto. For example, every spring our plant propagation class grafts potato roots to a tomato top. Tomatoes can also be grafted onto eggplant (which is actually very useful because eggplant roots are very resistant to flooding unlike tomato roots).
While the above examples are interesting, they’re also relatively common knowledge among horticulturists. Here’s the part that’s not common knowledge (or perhaps I should say here’s the part that I didn’t know about — I’ve been known to be ignorant of things that other people consider common knowledge before). Tomatoes can be grafted onto tobacco, and, if they are, they will have nicotine translocated to their fruit — not a lot mind you. Most of the nicotine ends up in the leaves and stems of the tomato plant, but still, why couldn’t a nicotine-laden tomato be developed which could help smokers kick the habit — in a semi-healthy kind of way?
I also found that tomatoes could be grafted onto jimson weed. Big mistake there. Jimson weed develops some pretty nasty alkaloids, and they end up in the tomato fruit. So, if you eat the fruit, your done for. In fact, I found an instance where 5 people were killed because they ate tomatoes grafted onto jimson roots. I am now curious about what happens if you graft tomato onto deadly nightshade — but not curious enough to actually try it.
More from our Ornamental Plant Production class tour across the state. One of our stops was James River Nurseries, Inc. Owner Mike Hildebrand has a built a unique and diverse business – they not only grow but do landscape design-build-install, all in the huge market of central and northern Virginia and beyond.
Here’s some arborvitae that spent the past few weeks at one of their job sites north of Richmond, waiting to be planting. They’re now back at the nursery. I was going to make this a quiz, but it’s unfortunately just too obvious.
Wow. Poor things never even made it into the ground.