The leaves of Crassula alpestris subsp. alpestris are succulent, dull green to pinkish red; triangular in shape. At the base of the leaf triangle the margins clasp the stem and then attenuate to a sharp tip that curves inward (upward). The arrangement of opposite leaf pairs occurs in four compact arrays. Each pair emerges at 90˚ angles above the previous one. This decussate pattern forms a neat structure on the stem, particularly on young stems. Similar patterns are seen in some other Crassula species.
The inflorescence of C. alpestris subsp. alpestris is almost flat-topped in the form of a thyrse, growing at the top of each mature stem. The flowers are small and white, sometimes tinged pink or red. The closed buds are pinkish at their tips. The flowers are sweetly scented, urn-shaped with a tube of fused petals that open widely with recurving petal tips.
The stamens and stigma don’t protrude from the flower mouth, providing some challenge and selectivity to pollinators. The successful ones are probably moths working at night. Blooming happens from midwinter to early spring.
The fruits are small capsules. The seeds they release are tiny, black and dust-like, suitable for wind dispersal (Manning and Goldblatt, 1997; Bond and Goldblatt, 1984; www.plantzafrica.com).