March 6, 2018

Exotic Nettles (Urtica spp.)

There are over 50 species of wild true nettles (Urtica spp.) which grow in various areas worldwide. Numerous of them has been used as medicinal, edible and textile plants. They all have more or less stinging hairs on their leaves and stems. Some (as New Zealand Urtica ferox) can be even dangerous to human life. There are both annual as well as perennial herbaceous species, or sometimes even woody shrubs. The seeds of most of them (if not all) have high oil content and can be pressed or grinded and boiled to fat edible oil obtaining. The leaves are often also edible. Seeds should be sown surface but they often need chilling period to germination (not always). Some species can be also very lovely ornamental. 
Mallorca Nettle - Urtica bianorii
I tried to grow 9 species so far (and 1 unusual one I photographed in wild state): 
Brazilian Stinging Nettle, Ortiga Crespa, - Urtica circularisthis is other annual species native to Argentina, Paraguay, Uruguay and southern Brazil. This is small annual herb with fine leaves 1-3 cm (0,4-1,2 inch) long, 1-3,5 cm (0,4-1,4 inch) broad, with burning hairs. This has been used as medicinal plant (hypotensive, diuretic, vasorelaxant, antioxidant) and vegetable herb. The plant is edible and considered to be highly nutritious for its minerals and vitamins content and it is usually included in various dishes in South America. Sow the seeds surface. They germinate easily (no pre-treatment required). It is very scarcely described and little known species. 

The seedlings

Plant in flowers
This nettle species is rather low and wide
Mallorca Nettle - Urtica bianorii (syn. Urtica atrovirens subsp. bianorii) this is lovely small perennial creating dense carpets, with tiny but very ornamental leaves. It burns only a little (not more than a common nettle). Native to Mallorca (an endemit at altitude 350-1000m - 1150-3300ft). Seeds should be sown surface. They germinate easily without any pre-treatment. Plant very rarely cultivated and resistant to some frost (at least to zone 7-8, maybe even 6).

This species has very small but lovely leaves

Roman Nettle - Urtica pilulifera - this is rare annual herb which can be used as vegetable (delicious young leaves - cooked and used as a potherb). The nettle beer is brewed from the young shoots. Also oily plant (edible oil pressed from large seeds), medicinal herb, fiber and dye plant and repellent insect pests. Very ornamental due to round inflorescences. It is native to southern Europe and Norther Africa. Sow the seeds surface or shallowly. They do not need any pre-treatment.

This species has dentate leaf margins and round infrutescences

Pellitory-leaved Nettle - Urtica dodartii - the species similar to Roman Nettle (and sometimes described only as its variety U. pilulifera var. dodartii) but with entire (not dentate on edge) leaves and larger seeds. It can be used in the same manner as U. pilulifera. Very ornamental. Sow the seeds surface. They germinate easily without any pre-treatment.
It is similar to U. pilulifera but has entire leaf margins

Hemp-leaved Nettle, Siberian NettleUrtica cannabina this is tall (0,5-1,5m = 2-5ft) herbaceous monoecious perennial with woody rhizome and burning hairs. The leaves 3-palmatisect or parmatipartite – something similar to hemp leaves. Native to China, Mongolia, Siberia, C and SW Asia, and Europe (Russia). Hardy at least to zone 5/6. This is excelent vegetable plant – young leaves – cooked are very nutritious food (high in vitamins and minerals, it makes an excellent spinach substitute and can also be added to soups and stews). Delicious nettle beer is brewed from the young shoots. To germination the seeds need a pre-treatment – sow them surface in autumn outside or cold stratify (store them in moist sand in fridge by a few months to time when they germinate).

Young plant

Plant in flowers
The infrutescences
Stingless Nettle, Fen Nettle - Urtica galeopsifolia This is an unusual vegetable which can be used especially in raw state (because the leaves do not burn). U. galeopsifolia it is perennial about 2m tall. Its leaves and tops of shoots have not stinging hairs, but lower parts of stems have them (and burn when touched as stinging nettle - U. dioica). This species has also very long and narrow, pubescent leaves - in comparison to wider and shorter leaves of stinging nettle. It is also later in flowers - in half of July (U. dioica in half of June, so one month earlier) and has first inflorescences on 13-22 node since base (U. dioica on 7-14 node). Fen Nettle does not grow on synanthropic sites - it grows only on natural communities - on winter-flooded wet natural thickets, edges of rivers, wet woodlands etc. This is diploid species. U. dioica is tetraploid and it is probably hybrid of U. galeopsifolia and other nettle species which has appeared in far past in Scandinavia (and extended its range to almost whole Europe). It is unknown if U. galeopsifolia is rare species or common one in wild state, because botanists have not researched its distribution and have not even known that it exists (due to it is very similar to common nettle on the first glance). It grows in western, central and eastern Europe, the most often on the south of latitude 60' N (so it is very frost hardy). The seeds probably need a cold (8 weeks of cold stratification or sowing in cool place in autumn, winter or maybe early spring) to germination – but I am not sure it because I have never sown it and I only observed it in wild state in southern Poland.
It has no stinging hairs in middle and upper parts

The leaves are usually long and narrow

It never grows in synantropic places. It grows only on marshes
A very similar to previous species is Kievan Nettle - Urtica kioviensis - hardy perennial with stems 0,8-1,2 m (= 2,5-4ft) tall (branched in upper part), above ground runners, long, narrow leaves, upper stipules connected at bases and seeds (achenes) 1-1,6mm long. In contrast to common nettle it is usually monoecious. The stems can create roots if they touch of a moist soil. It is apparently endemic to central and eastern Europe. It is native to Austria, Belarus, Bulgaria, Croatia, Czech Republic, Denmark, Germany, Hungary, Moldova, Romania, Russian Federation, Slovakia and Ukraine. In many areas very rare and endangered - it is classed as extinct in the Czech Republic, endangered in Belarus and near threatened in Hungary. In other countries it's status is unknown. Very poorly studied and little known species. Frost hardy do zones 5/7 and warmer. It can be used as a leafy vegetable in the same manner as common nettle. Very delicious. Seeds can be pressed (or grind and boiled) to oil obtaining.
Young plant

It is usually monoecious
The upper stipules are connected at bases
Plants in winter. It creates numerous above ground runners

I tried growing 3 other species yet but without success. But I am going to try again.
The first was Urtica magellanica - Magellan Nettle, Ortiga de Magallanestender perennial native to South America (Peru, Bolivia, Chile and Argentina). It is very similar in appearance to common nettle but is not resistant to frost. My only plant which I grew from seed has been killed by mealybugs before flowering.
Young seedling
It is very similar to common nettle but not frost hardy

Urtica flabellata - Fan-shape-leaf Nettle - small annual plant (to 6ich = 15cm tall) that forms tight clumps of dense, spiny, fan-shaped leaves. Makes a good tea or addition to soups. Also medicinal herb. It grows in natural range in high mountains in South America (Peru, Bolivia and Ecuador) and does not like a heat. Needs well drained soil. I sown it directly outside in late spring but young seedlings died fast. I need to try again but more carefully.
The seedlings
The last species which I try to grow is Urtica ferox - Tree Nettle, Ongaonga - endemic to New Zealand. Unlike other herbaceous species of true nettles, this is a large woody shrub to 3m (=10 ft) tall. It has unusually large stinging spines that can result in a painful sting that lasts several days (one person even died after burning by it). My plant died fast (killed by mealybugs). Maybe next time will be better.
The seeds of Utica ferox

This species has long and very sorely buring stinging hairs

There are numerous other nettle species worldwide. Maybe they are common in your area. If you live in any exotic place and could harvest nettle seeds for exchange please write to me.


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