- Name also: Small-flowered Touch-me-not, Smallflower Touchmenot, Small Yellow Balsam
- Family: Balsam Family – Balsaminaceae
- Growing form: Annual herb.
- Height: 20–50 cm (8–20 in.). Stem erect, unbranched, slender, glabrous, juicy.
- Flower: Irregular (zygomorphic), 10–15 mm (0.4–0.6 in.) long. Corolla of 5 pale yellow petals, 2 lower partly fused into a lip, uppermost helmet-like. 3 sepals, 2 small and green, lowermost modified into a pouch-like spur tapering into a straight tip. Stamens 5, fused, surrounding the pistil of 5 fused carpels. Inflorescence an erect raceme with 5–10 flowers.
- Leaves: Alternate, stalked, hairless, mostly on the upper part of the stem. Blade elliptic to ovate, thin, densely toothed (20–30 teeth per half).
- Fruit: Erect, 5-locular, pod-like capsule which bursts open at maturity and throws the seeds away.
- Habitat: Parks, yards, roadsides, waste ground.
- Flowering time: (June–)July–September(–October).
- Harmfulness: Harmful invasive species.
Small balsam is an annual which in Finland (and in some other European countries) is an established alien. It originates from Central Asia. In the 19th century it was brought to European botanic gardens, from where it escaped and became naturalized. It probably spread to Helsinki from St. Petersburg in the 1850s. Small balsam usually forms pure stands as other plants do not tolerate the strong shading of its dense foliage.
Small balsam differs from its relative, touch-me-not balsam (I. noli-tangere), in having an erect, rather than drooping inflorescence. It also has a straight-tipped spur on the largest sepal, whereas the spur of touch-me-not is curved.