Crassula sieberiana aka Siberian Pygmyweed

Crassula sieberiana, known by common names including Siberian Pygmyweed, Australian Stonecrop, Australian Pigmyweed, Austral Crassula, and Silver Crassula, is a small annual or short-lived perennial succulent herb in the family Crassulaceae. It forms low sprawling clumps with stems typically 10–50 mm long, occasionally reaching up to 200 mm in exceptional cases. The plant is native to Australia (occurring across all mainland states and territories as well as Tasmania), New Zealand (Three Kings, North, South, and Chatham Islands), and Lord Howe Island; it has been introduced to Hawaii.

The leaves are tiny and lanceolate, roughly 2–4 mm long and 1–3 mm wide, grey-green, pinkish, reddish-green, or red in colour, without petioles. Flowers are small, typically four-petalled, borne in spike-like or panicle-like arrangements in the leaf axils. Flower colour ranges from pale yellow to red. In New Zealand, flowering occurs from August through December, with fruiting continuing from October to March.

The species inhabits diverse ecological zones across its native range, from rock crevices in arid inland areas (such as Sturt National Park in NSW) to coastal regions with higher rainfall. In South Australia, it is listed as endangered. In New Zealand, it is classified as Not Threatened (2023).

Seeds are dispersed by wind, water, and potentially by adhesion to surfaces. The plant grows readily from fresh seed, though its short lifespan makes it unsuitable for commercial cultivation. It is not typically grown as a houseplant and is not a tree. Taxonomy within the species is debated; some authors recognise subspecies (including subsp. tetramera), but the current treatment in New South Wales does not formally distinguish them.