Pycnostachys urticifolia is a beautiful plant, with a mouthful of a name. While trying to find a more melodious way of referring to this species, I came across a number of equally-difficult common names; you may also call this species dark blue pycnostachys, groot ystervarksalie, or unkungwini. It is also known by some as simply “hedgehog sage”, so I will stick with that one.
Hedgehog sage is an aromatic perennial herb in the mint family. It grows ubiquitously in South Africa but even though it is a common plant (and in the mint family, known for medicinal and herbal uses), it does not appear to be used as food or medicine. It does have potential as an ornamental species complete with wildlife value; the PlantZAfrica web site lists it as a nectar source for butterflies and bees, as well as food for grasshoppers. The book Chewa Medical Botany mentions that hedgehog sage is used as a fly repellent in Chitipa, Malawi.
Hedgehog sage grows to a height of 1-2.5 meters. Its petiolate leaves are similar to those found in nettles (Urtica spp.), hence the specific epithet urticifolia (“nettle-like leaves”). The bright blue inflorescence is the part of the plant most likely to excite a gardener; dense terminal spikes burst forth from this shrub in great number late in the autumn. After flowering, the calyx (the sepals, collectively) becomes sharply spiny; all of the sources that I found describe the sepals as reddish-purple, but Vojtěch Zavadil’s photo (linked above) clearly shows them as light green, with only a purple tinge at the very tips. I find it interesting that the sepals are both able to protect the unopened flowers and (later) the maturing seeds by converting into spiky herbivore-deterrents. How efficient!