- Name also: Western Touch-me-not (USA, Canada)
- Family: Balsam Family – Balsaminaceae
- Growing form: Annual herb.
- Height: 30–70 cm (12–25 in.). Stem upper part slightly branched, swollen-jointed, juicy, fragile.
- Flower: Irregular (zygomorphic), 3–4 cm (1.2–1.6 in.) long. Petals 5, yellow, with faint red spots, 4 lowermost fused in pairs. Sepals 3, lowermost pouch-like, same colour as petals, gradually narrowing spur, which is usually bent downwards or forwards. Stamens 5, anthers fused. Gynoecium composed of 5 fused carpels. Inflorescence bent under subtending bract, a 2–4-flowered raceme. Self-pollinating closed dwarf flowers common.
- Leaves: Alternate, stalked. Blade elliptic–ovate, thin, with sparsely toothed margin (7–16 teeth on each side).
- Fruit: 5-parted, pendent capsule, which bursts open when ready, scattering the seeds into the air.
- Habitat: Stream-side broad-leaved forests, rich swamps, springs.
- Flowering time: July–September.
- Endangerment: Protected in the provinces of Oulu and Lapland.
Touch-me-not balsam germinates in the spring, and inch-high (2.5 cm) sprouts with their big, cordate cotyledons spend a long time gathering power for their flowering time. It is only in July or even at the end of July that the plant reaches its full size and splendour. Flowering touch-me-not balsam often stands out from a distance because its stands are often wide and dense. Its flowering time is long, from midsummer till the end of September. Only great yellow bumblebees and garden bumblebees have a sufficiently long proboscis to reach the flower’s pollen, but they do not always find the scentless flowers which are almost completely hidden by the leaves. Touch-me-not balsam ensures its seed production too with self-pollinating closed dwarf flowers. It has good reason for investing in its flowering time, because the annual species is completely reliant on its seed production.
Touch-me-not balsam’s name refers to the club-like capsule’s habit of exploding open at the least provocation: five lobes suddenly curl up from the bottom up and cast its seeds out in every direction. Touch-me-not balsam’s scientific name is a warning about this, meaning roughly “I am sensitive, don’t touch”.