By Norman C. Bezona
University of Hawaii at Manoa College of Tropical Agriculture and Human Resources
With warmer weather, nature is busting out all over and some folks are going crazy trying to fight a war on weeds! First, let’s define weed, because, as the saying goes: “one man’s meat is another man’s poison.”
A weed is sometimes defined as any plant growing in the wrong place.
Perhaps an even better definition of a weed is a plant for which we have not found a use. It might also be a plant growing in a place where we don’t want it.
Some folks like to think that a weed is anything that is not “native.” Or, maybe it is a plant we don’t like because we perceive it as ugly.
Personally, I try to come from a philosophy that God created All and it was good! By thinking positively and inclusively, I try to see the good in everything and everyone.
For example, Voltaire Moise and I are heading to Trinidad and Tobago in the Caribbean on a palm excursion. There, they are using one of our native plants, the beach naupaka, or Scaevola sericea, for erosion control. It is very popular from Florida and down through many of the islands southward. Our native naupaka is even used in hanging planters of multistory buildings. Landscapers love it because it is so hardy and attractive, but some folks there are upset with its use because it isn’t a “native” plant.
On the other hand, native plant lovers of the Caribbean are desperately attempting to save the mangrove forests along the coasts because they are essential to coastal protection and are considered the nurseries for birds, fish, shrimp and other sea creatures.
In the past, mangroves were used in Hawaii for the same reason, especially on Oahu near Kaneohe and Molokai where soil erosion was allowing mud into the bays and killing reef life. The mangroves filtered out the mud, thus protecting the reefs.
Now, the tide has turned, so to speak, and some folks are attempting to eradicate the mangroves in Hawaii. Several mangrove stands in West Hawaii have been eradicated and, along with them, the nesting sites for our native night crowned heron.
So what is the real story here? And who is right or wrong? I am not sure, but if God created it all and it was good, maybe it is just that we haven’t yet figured out the value of certain species.
Unfortunately, we sometimes find plants are used in an inappropriate manner. Then they may be incorrectly referred to as bad. Examples of this are the tobacco plant, the coca plant, marijuana and even grains that produce alcohol. So it is not that the plant is intrinsically evil, it is that we have misused it.
The digitalis plant may be used to poison someone or, in the proper amount, it may be used to save lives.
The terms “good” and “bad” are really human morality issues.
Nature just is.
Folks have good and bad behaviors or make good and bad decisions. Life forms like plants and animals may be used in a certain way, but we really can’t blame them.
It is really issues about our management of the world around us.
Kahili ginger is considered by some folks to be a horrible weed. But just for the other side of the story, Google Hedychium gardnerianum and take note of work being done with certain components of the plant that are being studied for their antioxidant properties. There are even studies on their use for treating Alzheimer’s disease.
A banyan tree in the park is great, but when one sprouts up in your roof gutter, we call it a weed.
Unwanted plants such as plantain and dandelions in lawns are usually the result of poor management. Lawns injured by insects, fungus, or nematodes will readily become infested with weeds. Improper mowing, watering and fertilization will lead to a problem lawn. So, don’t blame the so-called weeds for a poor lawn. They are often just a symptom of improper maintenance practices. By the way, plantain is used medicinally, and dandelions are edible.
When it comes to turf, proper establishment is important. Soil that is not infested with unwanted plant seeds such as nut grass is also a basis for preventing problems in a new lawn. After that, proper management practices that result in a dense, vigorous turf will aid in preventing unwanted species.
Once unwanted plants get established in lawns, it is difficult and expensive to gain control. Then you may have to resort to herbicides. Product availability is changing so fast with the pesticide misuse concerns that it is difficult to make general recommendations. Check with your local garden shop for solutions to specific problems.
If you end up having to pull weeds by hand, smile.
Let’s take a positive approach to “weeds.” Did you know that many of these pesky fellows are actually edible or medicinal? Plants we often label as weeds are usually types that appear wherever the soil has been disturbed. It is nature’s way to heal wounds caused by landslides, fire and humans or their activities.
Pig damage is a big issue wherever they have been allowed to breed without control. Disturbed land is ideal for weeds — or perhaps better labeled, pioneer species to thrive. They grow rapidly and often compete with what we may consider more desirable species. They mature large quantities of seed, and they are often difficult to control.
Weeds are often described as undesired plants, plants growing out of place, or plants that are a nuisance. Both the characteristics and the definitions of weeds emphasize that they are plants closely related to man. They come and go as man or his animals disturb the soil. Just as man has traveled and dominated the land, so have these species benefited from his activities.
Because of their origin being so close to the activities of man, many of the plants we call weeds have been discovered to be edible or medicinal and, indeed, are used locally as pot herbs throughout the world. When you eat Thai food, many of the tasty ingredients you find are thought to be weeds by some.
So when you go out to pull weeds, it’s easier if you know they could be for dinner or to heal the sick. And so you don’t fall into the trap of calling them bad, think of them as pioneer plants for which we haven’t found a use.
For example, one of our most common weeds is the Spanish needle (Bidens pilosa). The young shoots may be boiled and used as a vegetable dish, used cooked in salads or stews. The leaves may also be dried and cooked later. Many grasses are edible, especially the rapidly growing sprout or shoot of larger growing types. Bamboo is an example.
The common purslane or portulaca has leaves and tender shoots that can be eaten raw. They are often used in salads or cooked as a spinach dish.
The familiar cattails of swampy areas are a source of several kinds of food. The starchy tubers are edible as young flower spikes. Young leaves are also eaten.
There are hundreds of edible plants we call weeds. Our local kahunas, tribal shamans and folks who have recently migrated from Southeast Asia really know a lot about edibles and medicinal plants that we think of as weeds, so tap their knowledge where possible.
For a change, and perhaps for more peace of mind, let’s back off the concept of war with plants and try to see that there is good and beauty in all things. At the same time, let’s focus on keeping potential unwanted pioneer species from being introduced to Hawaii’s delicate ecosystem. Once here, it is almost impossible to eradicate them. However, the species that have been established here for a long time are probably here to stay. They can, and should, be managed to minimize any negative impact, but with limited financial resources, it is probably better to improve and support incoming agricultural inspection.
We can also learn to see the beauty, and possibly the value, of what is already here.