Stinging Nettle (New)

Introduction

The genus Urtica comprises about 80 species and is almost cosmopolitan, with most species in temperate regions of the northern hemisphere. Most may cause irritation upon contact with the skin. About half a dozen of these occur naturally in Africa. Of these, U. massaica, U. simensis, U. urens and U. dioica are most important. Both U. massaica and U. simensis are endemic to the continent, being respectively found around the Great East African lakes and the Ethiopian Highlands. They are both used as leafy vegetables. Urtica dioica and U. urens occur naturally along the Mediterranean in North Africa and both have also been introduced in Southern Africa, particularly South Africa. 
Urtica species can be found in a variety of habitats, including grasslands, forests undergrowth, forest edges and wetlands. Stinging trichomes of the leaves and stems have bulbous tips that break off when brushed against, revealing needlelike tubes that pierce the skin, injecting a mix of acetylcholine, formic acid, histamine, and serotonin, that causes itchy, burning sensation in animals including humans. Animals like hunting dogs running through stinging nettle thickets have been poisoned, sometimes lethally, by the massive accumulation of stings. The defensive mechanism is an effective deterrent against large herbivores, though the plant is important food for several butterfly species and aphids. Dried plants can be used as livestock feed, and heating or cooking the fresh leaves renders them safe for consumption.
Most Urtica species are potential vegetables, especially in the dried form. The leaves and young shoots of Urtica massaica and U. simensis are traditionally cooked and eaten as vegetable along with starchy foods. Urtica species are generally rich in nutrients, including vitamins A and C, iron, and calcium. 
Urtica species are important medicinal plants. The plants have been used as remedies for different ailments, such as high fever, diabetes, gout, and arthritis. Tea made from the leaves can also be used for hay fever, while creams have been developed for joint pain and skin ailments. The roots of the plant are used as a diuretic and to treat urinary disorders. The Maasai use the leaves to cure stomachaches, while the Kisii people use them for malaria treatment. In Tanzania, the roots and leaves are used for hepatic diseases. In Uganda, the leaves are used as a repellent against rats and for crop protection. Additionally, the plant's stems produce a strong flax-like fiber used to make strings, cloth, and paper. The plant's juice or a decoction formed by boiling the herb in a strong solution of salt can curdle milk and act as a rennet substitute. The juice can also be rubbed into leaky wooden tubs to make them watertight. 

(Bosch & Schippers, 2004, Grubben et al, 2004, Maundu et al., 1999).

Species accounts

Urtica massaica is an erect perennial herb that can grow to a height of 2 m high covered all over with stinging hairs about 2 mm long. Stems: are angles, arising from a rhizome creeping below the soil surface. Leaves: a dark green color, opposite heart-shaped with a serrated margin and a pointed tip. Flowers are dioecious, small and light-green to white, borne in long spike like florescence arising from the leaf axils. Fruits: small, green and flattened resembling those of tomatoes. U. massaica occurs in eastern DR Congo, Rwanda, Burundi, Kenya, Uganda and northern Tanzania. The plant occurs in clearings and natural glades in rainforests and moist evergreen bushland often near human dwellings, especially in cattle enclosures and cleared areas near gardens. Found in altitudes 1,500-3,250 m. The leaves of U. massaica can be consumed after being wilted and boiled, or consumed raw when young, similar to other Urtica species found worldwide. In addition to its culinary uses, U. massaica has a variety of medicinal properties. The Maasai community uses its leaves to alleviate stomach-ache, while the Kisii region of Kenya employs them to treat malaria. In Tanzania, the roots and leaves are macerated and used to treat hepatic diseases. The plant is also utilized in Rwanda and Burundi, both alone and in combination with other botanicals, to treat a range of maladies such as bruises, fractures, venereal diseases, rheumatism, and urethral leaks. Furthermore, the leaves of U. massaica are used in Uganda as a repellent for rats and to protect crops from grazing cattle.
(Maundu et al., 1999, Grubben et al., 1999, Bosch & Schippers, 2004).

Related species 
a.    Urtica dioica typically grows to a height of 1 to 2 meters (3 to 6 feet). The plant has a straight, erect stem covered in tiny hairs, which are known for their stinging properties. The leaves are opposite, serrated, and heart-shaped, with a dark green color. The plant produces inconspicuous flowers that are greenish and arranged in long, branched clusters. The plant's unique feature is its stinging hairs, which inject chemicals when touched, serving as a defence mechanism. The species occurs in moist sites along stream, meadow and ditches, on mountain slopes in woodland clearings and in disturbed areas. Despite this, stinging nettle is valued for its nutritional richness, including vitamins, minerals, and antioxidants. It has a history of traditional medicinal use for allergies, arthritis, and urinary tract disorders. Additionally, nettle extracts are utilized in skincare products (NC state extension. n.d).

b.    Urtica urens is a monoecious annual herb, erect or ascending growing up to 75 cm tall and branching at the base. Stipules c. 1.5 × 0.5 mm, narrowly lanceolate. Leaves 1.5-4 cm, ovate or elliptic, incised-dentate; the lower shorter than their petioles; petiole 3-5 cm long. The plant has clusters of small, greenish-white flowers form where leaves join stems. The seed leaves are round or slightly elongated with smooth edges and a notch in the tip. First true leaves and all later leaves have distinctly toothed edges. It can be a particular nuisance because the bristles or hairs on its leaves and stems give off a substance that causes an intense burning sensation. This species of stinging nettle is reputed to sting more strongly than other species of stinging Nettle. U urens is adapted to many environments, infesting a wide range of horticultural crops, especially where there is irrigation or summer rainfall. In pastures, it can become prevalent in situations rich in organic material or manure, such as stock camps, holding yards or watering points 
(Lazarides et al., 1997, Hyde, et al., 2021).
c.    Urtica simensis is a dioecious, erect perennial herb that grows to a height of 1 m tall. Almost unbranched, rhizome creeping and 0.25 mm long stinging hairs. The leaves are opposite with simple stipules fused. The plant is found in grassland and often in disturbed localities and near human settlement in Ethiopia. The plant is used as a vegetable. 
(Maundu et al., 1999, Grubben et al., 2004).

Ecological information

Light: Stinging nettle thrives in full sun conditions but will tolerate some shade. Shading makes the plant grow too tall with less dense foliage. Soil: This plant does best in loamy or clayish soils rich in nitrogen and phosphorus. It thrives in disturbed soil and often in abandoned dwellings, provided the underlying soil is rich. Stinging Nettle tolerates a wide range of pH levels, from very acidic to very alkaline. Altitude: In the tropics Urtica sp are mainly found in highlands where the weather is cool and humidity generally high but in the subtropics and temperate lands the species can be found in lower altitudes.

Agronomic aspects

Stinging nettle can be propagated by seeds and rhizomes. To propagate using the rhizomes simply dig up plants from an existing patch and move them to a new location. It is easy to do in spring when the plants are just beginning new growth. Stinging nettles spread readily through rhizomes. Gloves preferably should be worn when handling the planting materials to avoid irritation.
Stinging nettle can also be grown easily from seeds collected from existing plants. Seeds of stinging nettle are very tiny. This could be scattered over the surface of a tray filled with ordinary potting mix (soil and manure). A thin layer of soil is then sprinkled on top of the seeds. Some species of urtica may need light to germinate. Seeds sprout within 2 weeks; the seedlings can then be transplanted.

(Bosch & Schippers, 2004, Maundu et al., 1999).

Harvest and post-harvest practices and markets

Nettle plants offer edible parts, but caution must be exercised due to their barbs. The leaves and stems require cooking, blending, crushing, or drying to neutralize their stinging properties. 
To harvest nettle plants, use gloves to pick growing shoots this promotes new side shoots. Leaves tend to toughen when flowering sets in. When handling nettle plants in your garden, always don protective clothing, such as thick rubber gardening gloves, long sleeves and trousers. It is advisable to refrain from touching your face during the process.

Markets 
Urtica presents a range of value-added opportunities, including the processing of the plant into tea, supplements, tinctures, or dry ground vegetables. Urtica products have demonstrated efficacy in treating ailments such as allergies, inflammation, and arthritis. As the demand for natural and alternative remedies continues to grow, the market value of Urtica remains significant. Beyond medicinal applications, Urtica fibres are also sought after in the textile industry, where there is an increasing demand for eco-friendly and sustainable fabrics. Moreover, the cosmetics and personal care industry utilizes Urtica in the production of natural and organic skincare products, including creams, lotions, and shampoos. Increasingly the dried ground Urtica is being sold and used to fortify soups in Kenya.
Considering the wide range of applications and associated health benefits, the market value of Urtica is expected to keep rising. This makes it an appealing and potentially lucrative investment opportunity for entrepreneurs and businesses alike.
(Medicalnewstoday, n.d, Samanta et al, 2021, Gunjan et al, 2015)

Nutritional value recipes

Stinging nettle is a highly nutritious African vegetable that boasts numerous health benefits. 
The leaves are an excellent source of minerals such as calcium, potassium, phosphorus, and magnesium. The minerals are important in maintaining strong bones and teeth, regulating fluid balance, supporting muscle and nerve function, and more. The calcium content in the leaves helps reduce osteoporosis, and the polyphenols in the leaves help prevent and manage inflammation disorders, heart disease and diabetes.
Stinging nettle offers further health benefits. Its tea, high in vitamin C, can aid in treating urinary tract infections (UTIs). It also shows promise in alleviating symptoms of benign prostatic hyperplasia (BPH), a condition characterized by prostate enlargement. The plant promotes scalp blood circulation, which aids in hair growth, and it can be used to address skin issues like acne and eczema. Moreover, stinging nettle acts as a diuretic, helping eliminate excess uric acid and potentially reducing the risk of kidney and gallbladder stones (Bioltif, 2020, Osafo, 2021, Aluyor et al., 2022).
Table 1: Proximate nutritional composition of 100 g of stinging nettle leaves.

Source (Nutrient data): FAO/Government of Kenya. 2018. Kenya Food Composition Tables. Nairobi, 254 pp. http://www.fao.org/3/I9120EN/i9120en.pdf

$ Draining the water several times leaches away water soluble nutrients significantly.
a Lewis, J. 2019. Codex nutrient reference values. Rome. FAO and WHO
b NHS (refers to saturated fat)
c https://www.hsph.harvard.edu/nutritionsource/water/
d British Heart Foundation
e FDA
f NIH
g Mayo Clinic
Complimentary recipes
Drying. 
Dried leaves can also be grounded into a powder for use in cooking, to make tea, or as a nutritional supplement. Leaves can be dried in a dehydrator on the lowest temperature setting, about 35°C for 12 to 18 hours. Leaves can also be dried by hanging them in a well aired shaded area. Leaves can also be dried in a netting suspended in a shaded area. 

1.    IRIO (Kenyan recipe) Source; 
Ingredients 
•    60 g stinging nettle leaves
•    200 g potatoes    
•    200 g beans (dried)        
•    100 g green maize    
•    Enough water for cooking

Procedure
•    Select and soak the beans overnight. This significantly reduces the cooking time
•    Shell the maize and select the beans to remove unwanted particles
•    Pluck the stalks off the leaves, and then wash the leaves twice to ensure absolute removal of mud and insects. Set aside for use later
•    Mix and wash the maize and the beans together
•    Put these into a pot or cooking pan, and then add water to slightly cover the food and boil until they are all cooked i.e. when the beans are soft on pressing between the fingers. . If using pressure cooker, cook for 20 minutes and allow to cool on its own.
•    Add the peeled and cleaned potatoes to the maize and beans 
•    Without chopping, add the leaves to the pot and continue boiling until the potatoes are soft enough to be mashed. By now the water level should have greatly reduced 
•    Drain off any excess water. (This excess water can, however, be kept aside to soften baby food)
•    Mash the food until all the potatoes are all thoroughly mashed and the food evenly mixed

Variation:
To prepare a child’s dish from the same, eliminate the maize and mash till soft and light enough for a child. The food can be made lighter by adding the excess water drained out before mashing.
Also, stinging nettle leaves can be substituted with pumpkin leaves or leaves of kahurura (Cucumis ficifolia).

Source: Cookbook for traditional vegetables (IPGRI. 2006). Unpublished