Spilanthes acmella

Spilanthes acmella, also known as Spilanthes oleracea and Acmella oleracea is a unique and versatile plant that will add texture and interest to your garden. The compact pompom shaped flowerheads that are set atop elongated stems, begin as squat red affairs, they gradually elongate and turn yellow, retaining the red portion at the top. The leaves are dark green and the stems, leaf stalks and veins dark green with bronze-purple tones.
An easy to grow and low maintenance plant with a spreading and trailing habit, it can be grown in the ground or makes a wonderful container plant.

The pretty yellow and red cone-shaped flowers and leaves are non-toxic and have properties similar to Echinacea, they are used by herbalists to enhance the immune system, improve digestion and help nausea.
The name ‘Toothache plant’ comes from the numbing properties it produces when the leaves and flowers are chewed. The plants have long been used in India for the treatment of gum and dental problems. The flowers are the strongest part of the plant.

Spilanthes acmella is native to Brazil and Africa. It is a perennial in warmer climates but may be grown as an annual in temperate regions. It is considered frost tender, but it will maintain its greenness after most of your other plants have died from the cold.

Sowing:
Sow indoors in spring or direct sow in early summer
The plants should be started indoors or in the greenhouse early in the spring, so the seedlings are well established at the time of transplanting to the garden. You can even direct seed in the garden, but the plants will not attain the same size as plants started early. Damp and cool conditions should be avoided, or the seeds may rot.

Surface sow the seeds in pots or trays containing good seed compost. Do not cover the seed as they need light for germination. Water from the base of the tray and seal inside a polythene bag until germination which takes 7-14 days at 20-24°C (68-75°F).
Transplant the indoor seedlings when large enough to handle into pots and grow on.
If allowed to grow for too long in too small of pots, the plants will rapidly droop and wither due to lack of water and nutrients. If the plants start to droop before the soil has warmed up in the garden, then transplant to a larger pot. Pinch out after approx 8 weeks to promote branching. Make sure the compost is kept moist at all times.

Cultivation:
Plant them out into their permanent positions in late spring or early summer, after the last expected frosts. Space 30cm (12in) apart. Water regularly until mature. Spilanthes is a heavy feeder, preferring rich soils and an occasional side-dressing of organic compost. Full sun is tolerated as long as the plants are watered deeply and often. A little shade may reduce the water requirement without compromising plant growth.

Harvesting:
The leaf and buds may be harvested on an ongoing basis, as often as the plant can afford. For commercial harvest, or to put up a good stock of tincture for the winter, the plant should be harvested at its peak at the end of summer.

Culinary Uses:
The fresh leaves can be eaten and used sparingly like cress as an additive to salads; they are even combined with chillies to offset the burn. To me, the effect is vaguely recalled or hinted at by French Tarragon or better still by Water Pepper.

Medicinal Uses:
Toothache plants contain spilanthol which acts as an anaesthetic/analgesic. They also show anti-inflammatory, antibacterial, and antifungal properties and it is a sialagogue, stimulating the increased flow of saliva and consequently promoting digestion. The entire plant (root, stem, leaf and flower) is medicinally active. The dried plant, especially the dried flower buds retain their "zing" for up to a year after harvest.
Spilanthol's muscle relaxing effects have even meant that an extract of the plant has found its way into high-end face creams that claim to have a natural 'botox' effect.

Other Uses:
Members of the Spilanthes genus have various insecticidal ascribed to it. In particular S. acmella seem to kill the larvae of mosquitoes.

Nomenclature:
In 1763, Nikolaus Joseph von Jacquin created the generic name from the Greek spilos "spot" and anthos "flower", an allusion to the spot at the top of the inflorescence.
Other common names include Para Cress (after the Brazilian province), Brazil Cress, Alphabet Plant (from the Flemish ABC Kruid), and Australian Cress.