Edible Landscape

Since the early 1900’s Americans began the great migration to the cities, and in doing so gave up their foraging practices. In earlier times people often searched their property and nearby fields and hills for edible food. In some parts of the world this is still a common practice. 

The time has come to begin foraging within our ornamental gardens and see what nutritional edibles can be gleamed. Caution: Proper investigation is necessary to verify that the chosen plants are safe to eat.  Consuming the wrong plant can be disastrous.

Here is a short list of some well-known edibles in the United States. Check the internet, especially university websites for a more comprehensive list.

A. Weeds - If you can’t beat them, eat them!

1. Dandelions, Taraxacum officinale -Fresh dandelion leaves can be eaten raw, in salads, added to a stir fry, or boiled and steamed like spinach. They have a bitter taste, but boiling will help take that out. Dandelions also make a great addition to soups and stew. They are high in carotenes, iron, calcium and vitamins A and C. As a detoxifying agent, dandelions aid with liver, urinary and gall bladder disorders, diabetes and high blood pressure. Dandelion root tea is sold in local health food stores. 

2. Lamb’s quarters (Chenopodium album) is also called wild spinach with similar nutritional value to spinach. 
3. Burdock (Arctium Lappa) is a weed rich in potassium, iron and calcium. 
4. Common mallow (malva neglecta) the leaves, stems, and immature seeds are eaten raw or cooked. Mallow is reported to be rich in calcium, magnesium, potassium, iron, selenium, and vitamins A and C.

5. Purslane (Portulaca oleracea) is a succulent; the leaves, stems and flowers can be eaten either fresh or cooked. The leaves contain more omega-3 fatty acids than any other leafy vegetable plant.

Other edible weeds include chickweed, white and red clovers and plantain.

B. Edible Flowers

1. Marigolds are one of the most commonly grown ornamental annuals. When dried and crumbled, the petals of marigolds can substitute for the most expensive spice in the world: saffron. 
2. Roses, both the petals and the rosehips (fruit), are edible. Rose water is often used in scones, cakes, sherbets, salads and icings.  
3. Sunflowers – in addition to the commonly eaten seeds, the petals can be added to soups and stir-fry dishes. The sunflower buds can be steamed and eaten like an artichoke.

4. Daylilies (Hemerocallis sp.) - Some species (especially H. fulva) are cultivated in Asia for their edible flowers. The petals can be eaten raw or more commonly dried and used as a flavoring in soups. The young shoots should be cooked and have a pleasant sweet flavor. Even the roots are edible.

5. Nasturtium, violas, borage and calendula flowers are also edible and frequently used in salads.  

Here is a final thought: some vegetables can be planted as ornamentals in landscape gardening. As shown above, swiss chard with the bright red stems and large leaves of cabbage add a delicious touch to the surroundings.

Photo: University of California Master Gardeners of Sacramento County

Medicinal Teas of Hawaii: Mamaki and Ko’oko’olau

Mamaki (Pipturus albidus)  is a Hawaiian endemic plant occurring on all the main Hawaiian Islands except Ni'ihau and Kaho'olawe. It grows in moist to wet forests at elevations ranging from close to sea level to 6,000 feet. Mamaki ranges in height from 6 to 20 feet tall.

Dried or fresh mamaki leaves are used to make a tea often drunk by those feeling lethargic. The tea is also used to help with many internal disorders for the stomach, colon, bladder, liver, and bowels.  The fruit is eaten as a laxative or for stomach, colon and digestive problems. Infused leaves can be used in treatment for high blood pressure, high cholesterol, liver problems, and bladder problems.  In some people mamaki can cause mild agitation or insomnia.

Mamaki is the primary food source for caterpillars of the native Kamehameha butterfly. Planting this shrub in the garden will provide food for the butterfly as well as a healthy, invigorating tea for the gardener.

Mamaki is a highly variable plant. The leaves are dark-green on the top and white to gray underneath. Some varieties have reddish veins.  It is generally not suited for hot, dry coastal settings, but will grow well in urban landscapes with some shading. It will also do well planted in containers in part shade. The red-veined varieties appear to tolerate full sun better than green-leaved varieties. The mature plant recovers after pruning if no more than one-third is removed.

Mamake plants are usually propagated from seed. The fruit can be ripened in a plastic bag to soften the pulp. Seeds are then removed from the pulp by rubbing the fruit in a strainer under running water. The viable seeds will sink and the fruit pulp and other debris can be poured off. Seeds then need to be dried on a paper towel and stored. Once planted, seedlings will thrive in a well-drained soil in a semi-shaded to shaded location.  The plants can also be propagated from cuttings.   

Ko’oko’olau Bidens menziesii is in the sunflower or aster family.  It can be an annual or perennial shrub, ranging from 3 to 12 feet in height, growing in a wide range of habitats. The plant is found on Molokai and West Maui and on the leeward slopes of Mauna Loa and Mauna Kea on the Big Island.  It is easy to grow, preferring full sun and light to moderate watering. It grows well as a potted patio plant.

Ko’oko’olau was widely used by Hawaiians prior to European arrival. Its leaves were used as a revitalizing tea. Flowers were used to stimulate appetite. Today the tea is still sold; however, Bidens pilosa is often the species incorrectly labeled and sold as the traditional Hawaiian tea. 

Hapuu, the Hawaiian Tree Fern, vs. the Australian Tree Fern

                                                        
The Hawaiian tree fern is native to most of the Hawaiian Islands. Although once common, hapu’u stands have been reduced due to a large number of ferns being harvested for orchid media and landscape use. The last remaining large stands of native hapu’u are found on the Big Island.

The Hawaiian hapu’u  are very slow growing; the young ones grow at about 3.5 inches per year while the older plants grow even more slowly, eventually growing to  15-20 feet tall.  The unfurled fronds are covered with silky, red-brown wool-like fibers called pulu.  In the past, pulu was used for stuffing pillows and mattresses and for dressing wounds.

The Hawaiian tree ferns are relatively easy to grow. They grow best in well drained slightly acid soils and partial shade; they will tolerate full sun in cloudy upland areas. They need a steady supply of water and occasional light applications of a complete, slow release fertilizer. Old and injured fronds should be pruned. It is illegal to ship tree ferns or products from the ferns internationally. 

 The Australian tree fern, Cyathea cooperi, is considered invasive in the State of Hawaii due to aggressively out competing native plants in the forest understory. As a threat to  Hawaiian forests, this fern eventually displaces the native ferns, including the slower growing Hawaiian tree fern, or hapu’u.  


Although invasive, the Australian tree fern is being sold in Hawaii at many commercial plant nurseries. This fern grows to 40 feet tall and tolerates full sun in cool wet areas. The spores are spread by wind and can travel over 7 miles from the parent plant.

 The best diagnostic characteristic to distinguish between the Australian tree fern and the native hapu'u is the hairs on the leaf stems. With the  hapu’u, the hairs are either fine and reddish-brown for hapu'u pulu (Cibotium glaucum) or fine and black for hapu'u i'i (C. menziesii). The hairs on the Australian tree fern are broad and white.
     

                                                Cibotium menziessi

  Photos: Native Plants Hawaii, University of Hawaii

Tropical Favorites

Some favorite tropical fruits, spices and flowers all belong to the same plant order known as the Zingiberales. They include banana, ginger, cardamom, turmeric and the beautiful heliconia flowers.

Banana, sometimes referred to as a tree or palm, is actually an herbaceous plant since the trunk or stems do not contain lignin. Lignin is the substance that makes wood, woody.  

Ginger originates from Southeast Asia and is unknown in the wild but has been cultivated since ancient times. Ginger was introduced into Europe from China and introduced into Mexico and the Caribbean by the Spaniards. Today it is widely used in local medicines in India and the Far East. China and India are the largest producers of ginger.   

Cardamom is native to India. The dried fruits are used in medicine and as a spice.  Cardamom seeds, which have a pleasant aroma, are used in curries and breads.   

Turmeric, or olena as it is called in the Hawaiian language, comes from the root of Curcuma domestica; it is an important ingredient in curry powders.  Turmeric has been gaining recognition as an anti-inflammatory herbal remedy. Preliminary findings suggest that a chemical found in turmeric called curcumin may have carcinogenic retarding properties but these findings have not been confirmed. With its bright yellow color, turmeric is also used as a fabric dye. This species is unknown in the wild; it is sterile and does not produce fruit. Turmeric is also known as Indian saffron. 

Lastly, in the plant order Zingiberales there are over 100 different species of heliconia flowers.  They produce some of the most beautiful and commercially important flowers for both potted plants and bouquets. Heliconias require high temperatures, humidity and light intensity.  In the wild they grow mainly in forest clearings. The Bird of Paradise, which is the national flower of South Africa, is also in this group. 

Edible Ornamental Plants

In frontier times, people foraged the  nearby hills and fields for edible plants. Since the early 1900’s, however, Americans began the great migration to the cities and  eventually lost their foraging ability. Perhaps the time has now come to learn which ornamental plants and common weeds can be a  good source of nutritious food.

Here is a short list of some well-known edibles. Many university websites have a more comprehensive list of ornamental edibles.

A. Weeds - If you can’t beat them, eat them!

 1. Dandelions, Taraxacum officinale -Fresh dandelion leaves can be eaten raw, in salads, added to a stir fry, or boiled and steamed like spinach. They have a bitter taste, but boiling will help take that out. Dandelions also make a great addition to soups and stew. They are high in carotenes, iron, calcium and vitamins A and C. As a detoxifying agent, dandelions aid with liver, urinary and gall bladder disorders, diabetes and high blood pressure. Dandelion root tea is sold in local health food stores. 

2. Lamb’s quarters (Chenopodium album) is also called wild spinach with similar nutritional value to spinach. 

3. Burdock (Arctium Lappa) is a weed rich in potassium, iron and calcium. 

4. Common mallow (Malva neglecta) the leaves, stems, and immature seeds are eaten raw or cooked. Mallow is reported to be rich in calcium, magnesium, potassium, iron, selenium, and vitamins A and C.

 5. Purslane (Portulaca oleracea) is a succulent; the leaves, stems and flowers can be eaten either fresh or cooked. The leaves contain more omega-3 fatty acids than any other leafy vegetable plant.

Other edible weeds include chickweed, white and red clovers and plantain.

B. Edible Flowers

1. Marigolds are one of the most commonly grown ornamental annuals. When dried and crumbled, the petals of marigolds can substitute for the most expensive spice in the world: saffron. 

2. Roses, both the petals and the rosehips (fruit), are edible. Rose water is often used in scones, cakes, sherbets, salads and icings.  

 3. Sunflowers – in addition to the commonly eaten seeds, the petals can be added to soups and stir-fry dishes. The sunflower buds can be steamed and eaten like an artichoke.

4. Daylilies (Hemerocallis sp.) - Some species (especially H. fulva) are cultivated in Asia for their edible flowers. The petals can be eaten raw or more commonly dried and used as a flavoring in soups. The young shoots should be cooked and have a pleasant sweet flavor. Even the roots are edible.

Nasturtium, violas, borage and calendula flowers are also edible and frequently used in salads.  Bon Appetit! 

Caution: Before collecting, research the plant to verify it is edible, and more importantly, make sure it is properly identified. Eating the wrong plant can be disastrous.

The Beautiful Vireya

Vireya are part of the rhododendron family, classified as a subgenus. They are native to Southeastern Asia - New Guinea, Borneo, Sumatra and the Philippines, growing quite often in the cooler mountainous areas. On the Big Island of Hawaii, vireya, also called tropical rhododendrons, are successfully grown from Volcano down to the coast.  There are about 300 species of vireya. Azaleas are part of this group.

Vireya grow well in the sun.  Yet locations of intense sunlight along with high afternoon temperatures should be avoided. In this case filtered sun is best. On the other hand, planting vireya in the shade will produce leggy shrubs with inferior flower production. No hot summer sun, no heavy shade.

It is important to plant vireya in soils and potting mixes that have excellent drainage. In addition to growing them in the soil, and sometimes in cracks and crevices, they can also be found growing as epiphytes. An epiphyte is a plant that grows upon another plant such as a tree, but is not a parasite on that tree.  The epiphyte derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it.

Vireya are well adapted for growing in pots and may even grow well indoors in a well-lit room. They come in a variety of beautiful, vibrant colors such as salmon, pinks, orange and yellows.

For those interested in learning more about vireya, join the Hawaii Chapter of the American Rhododendron Society or search to see if there is a chapter in your area.

Trouble with Palms

"The bottom fronds of our triangle palm started to die, and then suddenly the whole palm fell over," a friend complained.

A significant pest of Pritchardia palms is the banana moth, Opogona sacchari. The triangle palm is also attacked by this moth. It seems that the female moth targets wounded or stressed palm tissue to lay her eggs. Stresses can include drought, flooding, mechanical wounding, poor nutrition, and herbicide injury. The larvae generally feed on decaying and dead plant tissue but will feed on living tissue, too, causing extensive damage. In affected palms, larval tunneling, along with the characteristic frass (insect droppings), can often be seen. Fully developed caterpillars measure just over an inch. The adults have greyish brown wings are 3/8 to 5/8 inches long.

The main treatment is prevention: keep palms growing well; give them adequate fertilizer, and supplemental water during a drought. Gardeners also need to be careful with the weed wacker! Female moths are looking for wounds to lay their eggs. Bt (Bacillus thuringiensis), an organic insecticide, can be applied to these wounds, as well as those caused during pruning.

For more information about this pest see the CTAHR Cooperative Extension Service publication, “Banana Moth – A Potentially Fatal Pest of Pritchardia and Other Palms”, by Scot Nelson and Mark Wright.  CTAHR stands for the College of Tropical Agriculture and Human Resources at the University of Hawaii. 

Ohia Trees (Metrosideros sp)

There are four distinct species of ohia tree that are endemic to Hawaii. In addition to genetic differences, environmental factors will cause physical variations in the trees. Elevation, rain, and temperature all have an effect upon these trees. 

In general, the shapes of leaves from trees growing in hot, dry deserts are often small in order to conserve water loss through the leaf. Contrast this to the large-leafed plants of the tropics. Ohias occur in a wide range of habitats, from just above sea level to 8,200 feet: from dry forests with less than 16 in annual rainfall to wet forests with more than 33 feet of annual rainfall. This along with its genetic propensity for variation will produce trees of diverse appearance. The species name, polymorpha which actually means many forms has eight varieties. Thus tree height and form, leaf shape and flower color are highly variable.

Concerning the care, ohia trees can be damaged and even killed from a lack of water. During periods of drought especially, supplemental watering will be needed. Trees growing in the pahoehoe lava (exhibiting a smooth, billowy, ropy surface) may do well when young and water requirements are low. Nevertheless, as trees increase in size, if adequate water is not supplied, they can dry out and even die.  Mulch will help, but of course, not piled against the trunk.

Since ohias are adapted to grow in low nutrient soils, beware of over-fertilizing. Slow-release fertilizers or natural compost is best. 

Growing Roses in the Tropics

Roses indeed are associated with cool climates like San Francisco, Portland and even London. They will, however, flourish in a variety of climates in Hawaii. The early missionaries brought the older type of roses, not hybrids, to the Islands.  

In Hawaii, roses can flower throughout the year in the warmer, sea level climates. They can also be in continuous bloom in the cooler mauka (mountain) communities.

In order to reap the benefit of these beautiful flowers, some care must be taken when growing and maintaining the plants. Here are a few essential points to consider:
 

• Roses require at least six hours of sun each day,
•  a well-drained soil  and
• adequate protection from strong continuous winds                                             

Rose bushes grown with less sunlight than six hours will tend to be tall and leggy with fewer blossoms.

Roses will benefit from mulch 4-6 inches. This reduces the temperature of the root environment, helps to control weeds, supplies nutrients to the ground and improves the physical characteristics of the soil. 

A fertilization program should be guided by a soil analysis. For further information on nutrition, and other rose topics, including specific cultivar recommendations, the UH CTAHR (College of Tropical Ag & Human Resources) website has an old, but good publication entitled, Rose Growing in Hawaii.

Roses are seldom free of pest. This is especially true in the tropics. Chinese Rose beetles are frequent and serious pests which come out after sunset and chew on the leaves. Tiny spider mites, aphids, thrips and grasshoppers will also attack the plants. Diseases like powdery mildew, black spot and rust are common. The rust appears on the underside of the leave as powdery pustules of bright orange spores. Diseases are particularly difficult to control when rainfall is high.