toxicity of elm wood

Can the sap from an elm tree be poisonous to humans? The power company recently cut down an old elm in my garden and I brushed my hand against the stump and got a splinter.

Within about twenty minutes my hand was swollen at least twice its normal size, was very painful, quite hot to the touch and itching like crazy. I ended up in the emergency room, and had to take antibiotics, but the doctor never indicated whether the extreme reaction had anything specifically to do with the type of tree.

We have an older book on plant-induced dermatitis, Botanical Dermatology by Mitchell and Rook (Greengrass, 1979) which includes elm among the trees which can cause “woodcutter’s eczema.” However, it may not be the sap of the tree itself which is the problem, but perhaps the lichens and liverworts which may be growing on the tree (some of which contain usnic acid and other substances which irritate human skin). Here is an abstract of an article which describes this:
Frullania liverwort phytodermatitis

If one were to saw elm wood which was covered in lichen or liverwort, the dust could be an irritant. You may have gotten a splinter which had dust on it. I’m not a medical professional, so I couldn’t say with any authority what may have happened. However, a splinter of any kind can cause inflammation, and if you happen to be especially sensitive to a particular substance, whether it is the wood or sap of the elm, or traces of dust from lichens and liverworts that were on the tree’s bark when it was sawed, then there might be a connection with the severe reaction you had.

Here is a link to an article (now archived) about splinters from American Family Physician (June 15, 2003).
It does mention wood splinters as a source of severe inflammatory reactions, due to the oils and resins they contain.

A chart which originally appeared in June 1990 issue of the journal American Woodturner lists different types of wood and their toxicity. Elm is included because its dust can be an eye and skin irritant.

bioluminescence and plants that emit light

I live in Nigeria. There is a plant, I don’t know the name, but I know some of its characteristics: mostly it grows near rivers or rocky areas, sometimes it flashes light in the night like a firefly, and there are red ants that climb it. Can you tell me what plant this is?

We certainly aren’t experts on the flora of Nigeria, but what you are describing could be bioluminescence. There are definitely fungi which are bioluminescent, and it’s possible the plant you are describing is host to a fungus (such as Armillaria, Omphalotus, Tricholomopsis, or Clitocybe) which does glow or emit light in the dark. The less scientific name for this phenomenon is ‘foxfire.’ The University of California, Santa Barbara maintains a web page on bioluminescence, and answers commonly asked questions about it. Here is an excerpt:

“There are not any luminous ‘flowering’ plants which have been discovered. (That would be neat if rainforests glowed, but I think it is only likely to happen if they have something else on the vegetation in there making the light). Fungi, some of which do luminesce, are not plants, and so they don’t qualify. The only ‘plants’ which do make light are the dinoflagellates, single-celled marine algae, and they are not plants strictly speaking.”

Although I seriously doubt this is what you are seeing, there is some work being done currently on developing artificially luminescent trees (using nanotechnology and genetic engineering: ). As mentioned above, plants are not naturally luminescent themselves, though they may be host to luminescent fungi and bacteria.

Another plant that I thought of is Dictamnus, which is referred to as the ‘gas plant,’ because it exudes a volatile oil which is flammable and can be ignited with a match. Although I haven’t heard of ants being interested in this plant, it would make some sense, because ants would probably be attracted to plant oils (just as they are attracted to nectar, or to ‘honeydew’ secreted by other insects on plants).

If you could send pictures of the plant you have noticed, include close-ups so that any fungal presence on the plant would be visible. That might be helpful in identifying it and determining the cause of the firefly-like flashes of light. The other consideration is that Nigeria has a high number of gas flares in the river delta which could also look like flashes of light at night.

khat tree intoxication

Recently I met an Ethiopian couple who were picking the reddened leaves on an otherwise green bush/tree in my front yard. The man explained this was a “cat” or “chat” tree, the leaves produce a drugged like state when ingested. He asked me if he could harvest the tree, and asked me not to tell any other Somalis, Ethiopians, or Eritreans in the neighborhood about my tree. He also told me that if I lived in Mogadishu, this tree would make me a wealthy man! He ate some leaves in front of me, and I tried a couple, but they were bitter and unpalatable to my palate. I experienced a feeling of empowerment, strength, and mental alertness. Obviously the “Chat Tree” has some relationship to the “Bongo” young Somalis chew.

During the worst of the anarchy in the late 1990s in Mogadishu there was a lot of news footage of the street gangs, high on the plant they were chewing, and armed with machine guns and machetes, creating havoc.

Do you know the history of this tree?

What are the properties that cause the intoxication?

What is the tree’s botanical name?

Should I report the tree’s existence to the authorities?

Can you tell me what I have here?

p.s.-These trees are common front garden bushes that were widely planted in Perth, Western Australia. Next time I see someone hanging out under one of them, I think I will know why!

The chat, or khat tree, is Catha edulis (Celastrus edulis), and the leaves and branchlets have properties that stimulate the central nervous system. In addition to the euphoric or inebriating properties, chewing the leaves can cause irritability, decreased appetite, gastric upset, constipation, and inflammation of the mouth. Habitual use can lead to periodontal disease, and increased risk of esophageal cancer. The active compounds are Alkaloid D-norpseudoephedrine, as well as other alkaloids, and tannins. (Source: Medical Botany: Plants Affecting Human Health by Walter H. Lewis; John Wiley & Sons, 2003, 2nd ed.)

The Handbook of Medicinal Herbs by James A. Duke (CRC Press, 2002, 2nd ed.) indicates that Catha edulis has been used medicinally to treat a great number of ailments, including asthma, depression, diarrhea, glaucoma, and low blood pressure. Use of khat is an ancient, socially acceptable tradition in the Afro-Arabian culture (and became known as a recreational drug in the USA after American soldiers were exposed to its use in Somalia. Khat is subject to legal restrictions in many countries. (Medicinal Plants of the World by Ben-Erik van Wyk; Timber Press, 2004).

As for whether to report the harvesting of leaves from your tree, that would depend on whether khat use is specifically prohibited by law in Australia.

Dragon’s Blood and herbal remedies

Someone told me about an herbal remedy called Dragon’s Blood which is made of the resin of Daemonorops draco. It’s supposed to be good for relief from pain and headaches. Can you tell me more about the plant, including its medicinal uses?

The plant in question, Daemonorops draco, is a type of palm (Family: Arecaceae). Here is the USDA Germplasm Resources Information Network page about this plant.

The common name Dragon’s Blood can refer to a number of different plant resins (such as those derived from Dracaena cinnabari, Dracaena draco, and Croton). The product you mention says it is derived from the palm Daemonorops draco. The resin of this plant has a history of use in folk medicine. Some of the plants are on the IUCN Red List of Threatened Species (Dracaena cinnabari is listed as vulnerable, as of 2009). This may be of interest to you because often the products you find for sale are not well-regulated, and there may be no way of verifying that the list of plant ingredients is either valid or complete.

Here is an excerpt:
“Few commodity dealers properly distinguish the various botanical origins of Dragon’s Blood items, and over-exploitation is starting to threaten some sources.”

As for medicinal and other uses of substances called Dragon’s Blood, here is more information from Cropwatch.org:

“The term ‘Dragons Blood’ refers to a product obtained from the resin layer consisting of diterpene acids found on the surface of fruits of the climbing palms of the Daemonorops genus found in SE Asia, and often sold out of Sumatra, Malaya & Borneo. These reddish resinous products (usually encountered as granules, powder, lumps (‘cakes’), or sticks (‘reed’) used in folk medicine as an astringent and for wound healing etc., and in other applications for colouring essential oils red to dark brown, in varnishes, staining marble, for jewelry and enameling work, and for photo-engraving. Mabberley (1998) suggests Dragons Blood was produced originally from Dracaena cinnabari, later from D. draco and more recently from Daemonorops spp.; Zheng et al. (2004) confirm this view and suggest substitutes for Dracaena spp. include Pterocarpus spp., Daemonorops draco and Croton spp.”

There is also an article by Jane Pearson published by the Royal Botanic Gardens at Kew (2002) on the uses of Dragon’s Blood.

Excerpts:
“The term ‘Dragons Blood’ is interchangeably used to refer to plants from three quite different families: Dracaena cinnabari (Socotra) and Dracaena draco (Canary Islands) in the Dracaenaceae family; the palm genus Daemonorops (Malaysia), and the genus Croton (South America) in the Euphorbiaceae
family. […] Although Daemonorops resin is similar in appearance, its origin and preparation are different to Dracaena resin. The fruits are covered in small imbricate scales through which the resin exudes, forming a brittle, red resinous layer on the outside of the fruits. Collection occurs just before the fruit is fully ripe. […] Although used in the same way as Dracaena, the powdered form of Daemonorops was used extensively, especially in America, as an acid resist by photo-engravers up until the 1930s. It also appears to be used in both traditional Chinese medicine and Chinese herbal folk medicine. Daemonorops is traditionally used to stimulate the circulation, promote tissue regeneration by aiding the healing of fractures, sprains and ulcers and to control bleeding and pain.” [My note: Daemonorops draco is referred to as Xue Jie in Chinese medicine.]

Please note that we are not medical professionals, so if you are considering using a substance which claims to contain Daemonorops draco, you should consult your healthcare provider. However, I can tell you that there are ongoing concerns about contamination of patented herbal remedies. University of Minnesota has information on traditional Chinese herbal medicine and related safety concerns.

lilac and elm wood and allelopathy

I have a huge planter to fill but don’t want to buy that much soil so I want to partially fill it with wood. I’m going to plant herbs in it but I wanted to know if the wood I have would make eating the herbs inadvisable. I have roots and branches from a snake bark elm and some large pieces of lilac. None of the wood is treated but I know some wood is poisonous and wasn’t sure about these two.

Before you go ahead with using wood to fill in the planter, another trick
you might try is to put an upended smaller pot inside the large pot, if
the planter is too deep. What you are looking for is a potting medium
with good drainage.

I am not familiar with snakebark elm (there is a snakebark maple, and a
lacebark elm–might it be one of these?) so I can’t give a conclusive
answer about its wood or roots. The phenomenon of plants which are toxic
to other plants is called allelopathy. The most famously allelopathic
tree is the black walnut. Apparently, lilac wood (Syringa vulgaris) has
the ability to raise the phenolics content in the soil, according to a
2004 scientific article (now archived) I found, from the 2nd European Allelopathy Symposium.

To be on the safe side, I would avoid using the lilac and elm wood as
filler in your planter, since there are better options.

You may find the information below useful:

Local gardener Mary Preus’s book, The Northwest Herb Lover’s Handbook
(Sasquatch Books, 2000) offers a recipe for potting soil for herbs grown in containers:

8 quarts compost, earthworm castings and/or composted chicken or steer
manure
4 quarts sphagnum peat moss
4 quarts perlite
4 quarts builder’s sand
1 cup all-purpose fertilizer mix (she has another recipe for this*)
3 tablespoons ground dolomitic limestone

2 pounds fish meal or crab meal
1/2 pound greensand
1/2 pound steamed bonemeal
1 pound rock phosphate
1 pound kelp meal

Virginia CooperativeExtension also has information on soil mixes for growing edible crops in containers:

“A fairly lightweight mix is needed for container gardening. Soil
straight from the garden usually cannot be used in a container because it
is too heavy, unless your garden has sandy loam or sandy soil. Clay soil
consists of extremely small (microscopic) particles. In a container, the
bad qualities of clay are exaggerated. It holds too much moisture when
wet, resulting in too little air for the roots. Also, it pulls away from
the sides of the pot when dry.

“Container medium must be porous in order to support plants, because roots
require both air and water. Packaged potting soil available at local
garden centers is relatively lightweight and may make a good container
medium.

“For a large container garden, the expense of prepackaged or soil- less
mixes may be quite high. Try mixing your own with one part peat moss, one
part garden loam, and one part clean coarse (builder’s) sand, and a
slow-release fertilizer (14-14-14) added according to container size.
Lime may also be needed to bring the pH to around 6.5. In any case, a
soil test is helpful in determining nutrient and pH needs, just as in a
large garden.”

plants and spontaneous combustion

My “gas plant,” Dictamnus albus, is finally flowering for the first summer ever, and I am starting to worry: can it spontaneously combust? It’s planted close to the house. I remember stories from a couple of years ago about houses in Seattle catching fire because of sun or extreme heat igniting compost or soil in planters. Are there plants besides Dictamnus that are especially flammable?

Dictamnus is not called the gas plant or the burning bush for nothing. It is in the same family as citrus plants, and contains extremely volatile oils that can indeed reach a high enough temperature to ignite. In Defense of Plants blog describes this aspect of the plant, and asks why a plant might have this capability (to burn out competing vegetation, or merely an unintended consequence of oil production). Excerpt:
“If air temperatures get high enough or if someone takes a match to this plant on a hot day, the oils covering its tissues will ignite in a flash. The oils burn off so quickly that it is of no consequence to the plant. It goes on growing like nothing ever happened.”
Some gardeners amuse themselves and amaze their friends by demonstrating this flare of flame, but I highly recommend you not try it if your plant is up against your house!

You can read more about the flammable properties (and garden merit) of Dictamnus in the June 1995 issue of American Horticulturist. See the article “Ignite the Night” by Robert L. Geneve.

There are other flammable plants. Areas that are accustomed to preparing for summer fire season (such as Grants Pass, Oregon and Ashland, Oregon) have information about which plants are most (and also which are least) likely to ignite. The flammable list includes ornamental juniper, Leyland cypress, Italian cypress, rosemary, arborvitae, eucalyptus, and some ornamental grasses.

If you are concerned about the proximity of this plant to your house, you might consider transplanting it elsewhere in fall, though be aware that Dictamnus has a taproot and is not fond of being moved.

hummingbirds and plants’ supply of nectar

I would like to know how the hummingbird’s feeding affects the level of nectar in flowers. I already know about which flowers produce nectar that will attract hummingbirds. My main concern is whether hummingbirds can use up a plant’s supply of nectar.

There has been some research which suggests that a plant’s production of nectar is regulated by hormones. Sometimes the hormone attracts one creature in order to repel another. The article excerpted below suggests that rapeseed plants produce nectar to attract ants that will defend them against caterpillars. Source: Max Planck Society for the Advancement of Science (March 29,2010):
“Jasmonic acid and related molecules are constituents of molecular signal transduction chains in plant tissues. These compounds – generally referred to as jasmonates – are synthesized when caterpillars feed on plants; they are signalling substances and belong to the group of plant hormones. By producing jasmonates the plant regulates its defence against herbivores e.g. by stimulating the synthesis of toxins. Moreover, previous studies have shown that jasmonates regulate the production of “extrafloral nectar”. This particular nectar, which is produced by special glands called “extrafloral nectaries”, has nothing to do with pollination, but attracts ants to the herbivore-attacked plants as defenders against their pests. The sugars in the nectar reward the ants for defending the plant. The same principle applies to floral nectar: nectar production in the flowers attracts and rewards pollinators which in turn contribute substantially to the seed yield. However, up to now, it has not been clear how nectar production is regulated in the flowers.”

In the book The Biology of Nectaries edited by Barbara Bentley and Thomas Elias (Columbia University Press, 1983), there is an essay called “Patterns of nectar production and plant-pollinator co-evolution” (by Robert William Cruden et al.) which states that “flowers pollinated by high-energy requiring animals [this would include hummingbirds] produce significantly more nectar than flowers pollinated by low-energy requiring animals, such as butterflies, bees, and flies.”

Similarly, plants whose pollinators are active in the day produce more nectar during the day, and plants pollinated by nocturnal creatures will make more nectar at night.
So clearly there is an intricate system of response between the needs of the plants and the needs of the hummingbirds, and the biology of individual plants has evolved to serve the plants’ interests which are tied to those of pollinators. In effect, the hummingbird can’t exhaust the nectar supply of the flowers, because the plant has adapted to meet its needs.