OMINOUS HOUSEPLANTS
Poinsettia Absolved
Sunny temperature reaching the 50s a few days ago enticed me outdoors for pruning. Today, with temperatures in the 20s, I’m back indoors (except for a very pleasant cross-country ski tour earlier) looking over what plants I have, or might have, growing indoors. Their ominous or not so ominous sides.
Mention poisonous houseplants and most people immediately think of poinsettias. Actually, poinsettia’s bad reputation is unfounded. The plant’s not really poisonous. Only a masochist would be able to ingest enough of this foul tasting plant to cause the occasional cases of vomitting that have been reported. This is not to pooh-pooh the toxicity of all houseplants. Many are poisonous.
No sane adult walks around the house plucking houseplant leaves to eat; the greatest danger from poisoning is to children. Ten percent of the inquiries to poison control centers across the nation concern plant poisonings, and the bulk of those inquiries concern children younger than three years. (But in only a small percentage of these cases does the child actually have symptoms of poisonings.)
Common Culprits
Years ago, I hosted philodendron and dumbcane (Diffenbachia spp.), two very common houseplants, in my home. These two plants are responsible for the first and second most reported poisonings, respectively.
Variegated philodendron
They are in the Araceae Family, a group of plants with needle-like crystals of calcium oxalate in their leaves and stems. When chewed, the crystals cause immediate pain in the mouth and throat, which commonly leads to swelling. This makes speech difficult and is the origin for the common name “dumbcane” for Diffenbachia species. Ingest enough leaves of either plant and vomiting and diarrhea, even death, could follow. Other houseplants in this family include elephant’s ear (Alocasia spp.), flamingo flower (Anthurium spp.), and caladium (Caladium bicolor).
Anthurium
Caladium
The “philodendron” that I grew and many people grow is commonly known as Swiss cheese plant, for its large, holey leaves. Botanically, it’s not a Philodendron, although it was originally classified as one. Now it’s botanical name is Monstera deliciosa. Deliciosa! A poisonous plant? This is one member of the Araceae that bears an edible fruit. The fruit resembles an ear of corn and tastes something like a combination of pineapple and banana. That’s when it’s ripe. Unripe, not so tasty, rich in oxalic acid, and poisonous.
Poinsettias are ranked third as far as the number of reported (not actual) poisonings nationwide. Although poinsettia really is not toxic, it’s a member of the Spurge Family, a family which includes many toxic plants. Guilt by association, perhaps. Members of the Spurge Family contain a milky latex in their sap, and this latex can cause dermatitis. A houseplant Spurge that does warrant caution is the Crown-of-Thorns, which, as long as we are talking about danger to children, also is heavily armed with stout thorns.
Now is the time of year when blooms on forced bulbs carry gardeners through the last leg of winter before spring planting. Most of these bulbs are in the Lily Family,
another family with many poisonous members. The daintiness of Lily-of-the-Valley belies the fact that it contains a potent cardiac glycoside (much like the digitalis found in foxgloves), which even leaches into the water of cut flowers. Hyacinths are wonderfully fragrant, yet also toxic. All parts of sunny daffodils contain lycorine, a toxin that can cause dermatitis with skin contact, and diarrhea and convulsions if ingested.
That toxin, lycorine, also is found in another winter bulb, amaryllis (Hippeastrum spp.), though amaryllis is not in the Lily Family.
And More
A few other houseplants in widely scattered plant families also are worth mentioning for their toxicity. Jerusalem cherry (Solanum pseudocapsicum), a houseplant with brightly colored berries, is in the Deadly Nightshade Family. The family name should tell you something about the plant’s toxic properties. Not all members of the family are toxic in the amounts normally ingested; if so, we’d have to give up eating tomatoes, eggplants, peppers, and potatoes.
Mistletoe is not a houseplant per se, yet it is a plant in the house at Christmas. The white berries, which tend to fall to the ground as the plants dry out, are toxic.
English ivy is a plant that is grown both indoors and outdoors. Unfortunately, its leaves are also toxic.
I don’t like to cast a somber cloud over these houseplants, but it’s important to know which are toxic so as to keep them beyond the inquisitive reach of very young hands. If a child does manage to ingest a plant, save part of the plant for positive identification, and then call a poison control center (http://www.aapcc.org/DNN/). It is not always advisable to induce vomiting, because this can further spread irritating materials.
Now why does an otherwise friendly looking plant — a philodendron, for instance — have to strike a menacing chord with a toxin in its leaves? Inside our homes, overwatering or underwatering probably is the major threat to any houseplant’s existence. But out in the jungle, a philodendron needs some way to ward off a big gorilla who might find the leaves an appetizing salad. In this case, a burning, swollen mouth is a good deterrent.
AN ICEY BEGINNING, WITH KIWIS
Pruning Weather
Yesterday was a fine day for pruning, windless with a sunny sky and a temperature of 19 degrees Fahrenheit. The ice storm had turned this part of the world into a crystal palace, with branches clothed in thick, clear sleeves of ice. 
From an auspicious vantage point, a pear tree glowed like a subdued holiday tree as hints of sunlight’s reds and blues refracted from the natural prisms on the branches.
Witchhazel flowers
What a pleasant setting for pruning! The usual recommendation is to hold off pruning until after the coldest part of winter, which typically occurs in late January and early February, is over. I’ll admit to rushing outdoors, pruning shears in hand, before that time period, with some plants not long after they dropped their leaves in autumn. That was with plants, such as gooseberries and currants, least likely to be damaged by cold weather.
I was anxious to begin pruning in earnest as an excuse to get outdoors and because I have lots of plants to prune, mostly fruit plants. It all needs to be done before leaves unfurl in spring. And, as spring inches closer, sowing seeds, spreading compost, and other gardening activities increasingly vie for my time.
So I’m out in the crystal palace working on my hardy kiwifruit vines (Actinidia arguta and A. kolomikta). In case you’re unfamiliar with this plant, it’s a dead ringer for the fuzzy, kiwis you see in the markets — except that hardy kiwifruit is grape-size with a smooth, edible skin. The resemblance is even greater beneath the skin — except that hardy kiwis are sweeter and more aromatic. And while a fuzzy kiwi vine will sulk or die back below 10 degrees Fahrenheit, hardy kiwis tolerate winter weather below minus 20 degrees Fahrenheit.
Kiwi Training and Pruning
A hardy kiwi vine bears fruits on new, growing shoots originating off one-year-old stems. 
The goals in pruning are to keep the plant reined in to a convenient size for easy harvest, to eliminate enough stems so that those that remain bathe in sunlight and air, and to coax growth of new stems off which will emerge, the following year’s fruiting shoots.
Kiwi vine, before pruning
Pruning also removes plenty of one-year-old stems. That cuts down yield but lets the vines pump more goodness into fruits that remain, for better flavor. (Pruning kiwis is described and also diagrammed in my book The Pruning Book.)
Training a kiwi vine to some sort of system keeps the vigorous growth organized. My plants grow on a trellis of metal or locust T-posts spaced 15 feet apart, with 5 wires (actually nylon monofilament) running perpendicular to and spaced out across to the tops of the T’s. Each kiwi trunk runs from ground level up to the middle wire, at which point it bifurcates into two permanent arms, called cordons, running in opposite directions along the middle wire. Fruiting arms grow out perpendicularly to the cordons and the wires, draping themselves over the two outermost wires on either side of the the cordons.
I actually began pruning a couple of weeks ago, starting to disentangle the stems by walking along on either side of the row with my cordless hedge shear, shortening any stems to a few inches beyond the outermost wires. Yesterday I began cutting any two-year-old stem — any stem that fruited last summer — back to its origin or to a one-year-old stem near the its origin. The one-year-old stems, those a little more than pencil thick of moderate vigor, will bear fruiting shoots this year in late summer or fall.
After all this pruning, plenty of one-year-old stems remain, too many for top notch fruit. So I’ll move down the cordons and remove enough one-year-old stems so that none is closer than eight to twelve inches from its neighbor.
Not done yet. In spring, after growth has begun, I’ll clip each one-year-old stem back to about 18 inches.
If you grow grapes, you probably noted that they bear and can be pruned similarly to the kiwis. I even grow some grape vines along the same trellis as the kiwi vines.
The main difference is that grape vines’ one-year-old shoots can be cut back more severely than the kiwi stems. Mine get shortened to a couple of buds each, which is only about three inches, from the cordon; it’s called spur pruning. Everything else is the same.
Ice is Nice, Sometimes
Those sleeves of ice on the kiwis actually made pruning easier. A sharp tug on a cut stem quickly disentangled it and let it slide free from its neighbors.
All this ice did, of course, weigh down branches of large trees which, coupled with strong winds after the storm, sent many limbs plummeting to the ground. Particularly surprising were my birch trees, a tree known for the limberness of its trunk, a characteristic immortalized in Robert Frost’s poem Birches:
I’d like to go by climbing a birch tree,
And climb black branches up a snow-white trunk
Toward heaven, till the tree could bear no more,
But dipped its top and set me down again.
That would be good both going and coming back.
One could do worse than be a swinger of birches.
This storm was more than two of my multi-stemmed birches’ trunks could bear; they cracked. But Mr. Frost was writing about white birches. Mine are river birches.
A HOUSEPLANT, AN “ALMOND,” AND PAPER
Easiest Houseplant of All?!
What with the frigid temperatures and snow-blanketed ground outside, at least here in New York’s mid-Hudson Valley, I turn my attention indoors to a houseplant. To anyone claiming a non-green thumb, this is a houseplant even you can grow.
Most common problems in growing houseplants (garden plants also) come from improper watering. Too many houseplants suffer short lives, either withering in soil allowed to go bone dry between waterings, or gasping for air in constantly waterlogged soil. Also bad off yet are those plants forced to alternately suffer from both extremes.
The plant I have in mind is umbrella plant (Cyperus alternifolius); it requires no skill at all in watering. Because it’s native to shallow waters, you never need to decide whether or not to water. Water is always needed! The way to grow this plant is by standing its pot in a deep saucer which is always kept filled with a couple of inches of water. What could be simpler?
One caution, though. The top edge of the saucer does have to be below the rim of the pot. Umbrella plants like their roots constantly bathed in water, but not their stems.
Lest you think that umbrella plant sacrifices good looks for ease of care, it doesn’t. Picture a graceful clump of bare, slender stems, each stem capped with a whorl of leaves that radiate out like the ribs of a denuded umbrella.
The stems are two to four feet tall, each leaf four to eight inches long. A dwarf form of the plant, botanically C. albostriatus, grows only a foot or so high, and has grassy leaves growing in amongst the stems at the base of the plant. There’s also a variegated form of umbrella plant, and a wispy one with especially thin leaves and stems. 
Umbrella plants aren’t finicky about care other than watering. They grow best in sunny windows, but get along in any bright room. As far as potting soil, your regular homemade or packaged mix will suffice. Umbrella plants like a near-neutral pH, as do most other houseplants.
Want More?
As the clump of stems ages and expands, they eventually get overcrowded in the pot, calling out to be repotted. You could move it to a yet larger pot, or make new plants by pulling apart, cutting if necessary, the large clumps to make smaller clumps and potting each of them separately.
One way wild umbrella plants propagate is by taking root where their leaves touch ground when the stems arch over. You can mimic this habit indoors if you want to increase your umbrella plant holdings without dividing the clump. Fold the leaves down around the stem with a rubber band, as if you were closing the umbrella. Cut the stem a few inches below the whorl of leaves and poke the umbrella, leaves pointing upward, into some potting soil — kept constantly moist, of course.
An Almondy Relative
Though you may be unfamiliar with umbrella plant, you probably have come across its near-relatives either in the garden or in literature. One relative is yellow nutsedge (C. esculentum), a plant usually considered a weed and inhabiting wet soils from Maine down to the tropics.
The edible nutsedge, also C, esculentum, usually called chufa or earth almond, is not invasive, at least in what I’ve read from many sources, and in my experiences growing the plants. It’s a perennial that has been cultivated since prehistoric times and was an important food in ancient Egypt.
But esculentum in the botanical name means “edible,” and refers to the sweet, nut-like tubers the plant produces below ground. I grow this plant, and now consider it quite esculentum, with a taste and texture not unlike fresh coconut. 
The main challenge with this plant is clearing and separating the almond-sized tubers from soil and small stones.
Storage improves their flavor, but they must be dried for storage, at which point they become almost rock hard. Give them an overnight soaking and they’re ready to eat as a snack or incorporate into other edibles or drinkables.
Paper Plant
Umbrella plant’s other famous relative is papyrus (C. papyrus), a plant that once grew wild along the Nile River. In ancient times, papyrus was used not only to make paper, but also to build boats and as food. Papyrus looks much like umbrella plant, and being subtropical, also would make a good houseplant. But with stems that may soar to fifteen feet in height, except for the diminutive variety King Tut, this species is too tall for most living rooms.
The Egyptians never recorded their method for making papyrus into paper but the Romans learned the process from the Egyptians and Pliny the Elder, a Roman, wrote about it in the first century B.C.
Genuine, Egyptian papyrus
Here’s how: You put on your toga and sandals (the latter also once made from papyrus), and prune down a few umbrella plant stalks. Cut the stalks into strips and, after soaking them in water for a day, lay them side by side in two perpendicular layers. Make a sandwich of the woven mat surrounded on either side by cloth, to absorb moisture, surrounded on either side with pieces of wood, then press.
In Egyptian sunlight, you could figure on the paper being dry and ready for use after about three weeks. Cut it to size to fit your printer.
