White dead nettle

This article refers to UK conditions. Transposition to any other climatic zone or part of the world may need some adaptation or have some unforeseen consequences.

Agroforestry can be described as the practice of establishing and maintaining a system of trees, shrubs, herbaceous perennials and other plants aiming to achieve useful outputs from minimal inputs.

One of the strengths of an agroforestry system (sometimes called a 'forest garden') is its diversity. On a variety of scales, from small to large, the system encapsulates a wide variety of different plants. This diversity of plants encourages in turn a diversity of animals: micro-fauna in the soil, insects and birds in the air, and in some cases larger animals.

Diversity makes for a resilient system. The polar opposite of a monoculture, it resists shocks like disease, predation, and extremes of weather conditions, not only because its constituent parts differ in their resistance to these shocks, but also because they form a community that generate and share resources as well as provide shelter for each other.

A key role of plants selected to become a part of an agroforestry system is to attract beneficial insects. They are beneficial because they eat other insects that feed on plants; or because they perform a pollinating function.

The flowers of Lamium album, otherwise known as white dead-nettle, attract pollinators because their flowers provide a high-value source of nectar that is attractive and easily accessible. Further, the flowers are available at any time (in UK conditions) from March all the way through to December, thus providing valuable early and late nectar which might otherwise be hard to find.

Botanically quite unlike the stinging nettles (Urtica dioica) that it closely resembles, it nevertheless does well in much the same habitat. Both distantly related cousin species are often seen growing together. Perhaps more a consequence of convergent evolution? It certainly serves them well as they are less predated on as a consequence: who would want to risk dealing with the defences of a stinger?

That close relative of the white dead-nettle, purple dead-nettle (Lamium purpureum) is a short-lived annual, as opposed to a perennial for P. album. Its nectar is similarly available for pollinators, however, as individual plants can germinate under a wide variety of conditions.

The flowers of P. album are very successful in attracting pollinators. They secrete certain oils that are very fragrant that these insects are attuned to. The lower part of the flower is a "landing platform" (underneath the large hood) with 'guides' directing the pollinator to the centre of the flower - just like in snapdragons, violets, and orchids.

Bumblebees are especially adapted to take advantage of the bounty of nectar that white dead-nettle flowers offer. Their long tongues allow them to stand at a distance and reach the nectar down the long landing-platform. This works both ways: the larger size of this insect means that as it lands its back gets brushed by the pollen-covered stamens hidden in the hood.

Smaller insects may be able to just slip inside the long narrow funnel of the flower anyway and reach the nectar. Others choose a different strategy to access the nectar: they break into the side of the flower by eating a hole in the petal.

The flowers and leaves of the white dead-nettle have other uses for people too: as food sources. The leaves are palatable for longer than those of stinging nettles, are very rich in certain essential nutrients, and can be used in much the same way as spinach. The base of the flowers are rich in nectar: the flower can be picked and the end nibbled for a sweet treat.

Those insect predators that have adapted to evade this nettle's mock defenses are in turn prey to other beneficial insects that are partial to aphids and caterpillars - and valuable crop plants don't have to be sacrificed either!

Companion planting could be another benefit that this plant species has to offer: vegetables and in particular potatoes seem to benefit from being grown in close proximity - much like how raspberries benefit from being grown close to stingers.

Propagation is performed usually by root cuttings or by seed. Already existing plants can be dug up (either whole or in part), and individual sections of the plant separated and potted up in autumn or spring. Water well, place under a cold frame and don't allow to dry out. Usually after at least a few weeks the plant should be good to plant in another location, depending on conditions and the time of year.

Alternatively, if seeds can be sourced, they can be sown in segmented trays of fine soil (usually potting compost is specified but it doesn't matter as long as the soil is reasonably fine like breadcrumbs), thinly covered, then left out in the autumn. Find a safe spot out of direct sunlight, cover the trays with wire netting (to deter mice and birds) and leave there for the winter. With any luck, there should be plenty of seedlings germinating!

White dead-nettle makes in my view an excellent addition to a varied and diverse agroforestry system: it protects the soil, attracts beneficial insects and has potential as a food source. Agroforestry systems thrive on diversity: when conditions are bad for some species, others can fill the gaps. Meantime, a wide variety of wildlife moves in, and benefits the surrounding area.

As a part of a unitary but diverse system, they help us realise our essential connection to it; and through it, to other people.