Crassula arborescens is the second most widely cultivated tree-forming species in the genus Crassula, surpassed in popularity only by the ubiquitous jade plant, Crassula ovata. Known as the silver jade plant, silver dollar plant, Chinese jade, or tree crassula — and as beestebal in Afrikaans — this striking succulent is prized for its almost perfectly round, blue-grey leaves coated in a distinctive powdery wax. In its native South African Karoo, Crassula arborescens develops into a stout, gnarled shrub up to 2–3 m tall with a thick, sculptural trunk that evokes a miniature baobab. Its silvery, coin-shaped foliage and low maintenance requirements have made it a favourite among succulent collectors, rock garden designers, and bonsai enthusiasts worldwide.
Taxonomy and Naming History
The species was first described as Cotyledon arborescens by Philip Miller in the eighth edition of his Gardener’s Dictionary in 1768 — the same publication in which Crassula ovata was first documented. It was transferred to the genus Crassula by Carl Ludwig Willdenow in the fourth edition of Species Plantarum in 1798, yielding the currently accepted name Crassula arborescens (Mill.) Willd.
The principal synonyms recorded by POWO are:
- Cotyledon arborescens Mill. (1768) — the basionym
- Crassula arborea Medik. (1783)
- Crassula cotyledon Jacq. (1781)
- Crassula cotyledonifolia Salisb. (1796)
- Cotyledon punctata Lam. (1786)
- Sedum arborescens (Mill.) Kuntze (1898) — illegitimate name
- Toelkenia arborescens (Mill.) P.V.Heath (1993)
POWO recognises two infraspecific taxa: Crassula arborescens subsp. arborescens and Crassula arborescens subsp. undulatifolia Toelken. The latter, often sold under the trade name ‘Blue Bird’ or confusingly mislabelled as Crassula ovata ‘Undulata’, is a distinct subspecies restricted to the Klein Winterhoek Mountains of the Eastern Cape.
Etymology
The genus name Crassula derives from the Latin crassus (“thick, fat”), a reference to the fleshy, succulent leaves characteristic of the entire genus. The specific epithet arborescens means “becoming tree-like” in Latin, describing the species’ growth habit — it is one of only three or four taxa in the genus that develop into genuinely tree-sized plants in the wild.
The common name “silver jade” directly contrasts the plant’s blue-grey, pruinose foliage with the glossy green leaves of the standard jade plant, Crassula ovata. “Silver dollar plant” alludes to the nearly circular leaf shape and silvery colour, reminiscent of a large coin. The Afrikaans name beestebal (“beast bulb”) refers to the species’ bulbous, swollen stems.
Natural Habitat and Distribution
Crassula arborescens subsp. arborescens is native to the southern regions of South Africa, with its core distribution in the Little Karoo (Klein Karoo) and Central Karoo of the Western Cape. Its range extends from the Hex River Valley in the west through the Little Karoo basin (Montagu, Barrydale, Ladismith, Calitzdorp, Oudtshoorn) to De Rust and Uniondale in the east, and northward through the Great Karoo as far as KwaZulu-Natal and Eswatini (formerly Swaziland). A disjunct population has been recorded on hills north of Vanrhynsdorp, separated from the main range by a significant geographical gap — a distributional anomaly noted by Tölken (1997) with no apparent explanation related to human activity or morphological differentiation.
Crassula arborescens subsp. undulatifolia has a much more restricted range, confined to the southern parts of the Klein Winterhoek Mountains in the Eastern Cape, where it grows on sandstone and shale-derived soils in rocky, gravelly conditions.
The species is assessed as Least Concern (LC) and is described by SANBI as occurring in abundance throughout its range, thanks in part to its prolific vegetative reproduction.
Vegetation type and ecology
Crassula arborescens grows in Succulent Karoo and Albany Thicket vegetation on rocky hillsides, slopes, cliff faces, and valley floors, often in association with other large succulents. Its typical companions include Tylecodon paniculatus, Cotyledon orbiculata, Aloe ferox, Aloe microstigma, Crassula perfoliata, Crassula rupestris, Euphorbia species, and Portulacaria afra. The species favours exposed, sunny positions and often colonises steep, north-facing slopes (the warmer aspect in the Southern Hemisphere) where competition from non-succulent shrubs is reduced by aridity and shallow soils.
When branches break off — whether from wind, animal activity, or gravity on steep slopes — the detached pieces root freely wherever they come to rest, forming dense colonies. This vegetative vigour means that Crassula arborescens populations can be locally very abundant, even dominant, across suitable hillsides.
Climate across the natural range
The climate of the Little Karoo and Central Karoo is markedly more arid, more continental, and more frost-prone than the coastal thicket environment of Crassula ovata. This is an important distinction for cultivation.
Rainfall. The Little Karoo lies in the rain shadow of the Cape Fold Mountains and receives modest annual precipitation. In the valley floors around Oudtshoorn — the heart of the range — mean annual rainfall is approximately 170–250 mm, distributed bimodally with slight peaks in spring (October–November) and autumn (March–April), and relatively drier mid-summer and mid-winter months. On the surrounding mountain slopes, totals can reach 300–400 mm. Further east and northeast, as the range extends toward KwaZulu-Natal, rainfall increases and shifts toward a summer-dominant pattern. Overall, this is a significantly drier environment than the 500–900 mm received across the range of Crassula ovata.
Temperatures. The Little Karoo climate is classified as semi-arid (Köppen BWk to BSk), with hot summers, mild to cold winters, and large diurnal temperature swings owing to the inland, basin-like topography and clear skies. Around Oudtshoorn, average summer maxima reach 28–35 °C (December–February), with extreme events occasionally exceeding 40 °C. Average winter maxima are a pleasant 17–18 °C, but the nights are cold: average winter minima fall to 5–7 °C, and the region experiences 50 to 60 frost days per year on average. Winter night temperatures regularly drop to 0 °C and can occasionally fall to –3 °C or below during cold spells associated with post-frontal conditions and radiative cooling in the valley floor.
In the northern extensions of the range (Great Karoo, KwaZulu-Natal midlands), frost can be even more frequent and severe, with historical minima occasionally reaching –5 °C to –8 °C at altitude.
Implications for cultivation. The natural climate of Crassula arborescens is considerably harsher than that of Crassula ovata: lower rainfall, higher summer heat, more regular frost, and sharper day-night temperature swings. This means the silver jade is genuinely drought-adapted (more so than Crassula ovata), tolerates strong direct sunlight without complaint, and handles cool-to-cold winter nights — provided the substrate is dry. However, like most Karoo succulents, it is poorly equipped for prolonged winter wet combined with cold, which is the typical failure mode in maritime European climates.
Botanical Description
Growth habit and stem
In habitat, Crassula arborescens forms a large, well-branched, rounded evergreen to semi-deciduous shrub, typically 1 to 2.5 m tall, occasionally reaching 3 m. Old plants develop a thick, gnarled trunk and short, stout branches that give the plant a convincing tree-like silhouette — one of only three or four Crassula taxa to achieve this stature. The bark is smooth and grey-green on young growth, becoming fissured and grey-brown with age. Branches are succulent and brittle, breaking cleanly under stress — a trait that facilitates the species’ vegetative dispersal strategy.
Leaves
The leaves are the key ornamental feature and the main identification character. They are opposite, decussate, held slightly erect and upward (a posture that reduces surface exposure to the sun and limits desiccation), broadly obovate to almost orbicular, 30–70 mm in diameter, thick and fleshy, and coated with a conspicuous blue-grey, powdery, waxy bloom (pruinose surface). The leaf apex is rounded with an obscure, tiny sharp tip (mucro). The leaf margins are typically tinged dark red — a feature that becomes more pronounced in bright light and cool temperatures.
The pruinose coating is a diagnostic character: it gives the foliage its distinctive silvery appearance and distinguishes Crassula arborescens at a glance from the glossy, smooth, green leaves of Crassula ovata. The waxy bloom also serves an ecological function, reflecting solar radiation and helping the plant stay cool during the extreme summer heat of the Karoo.
Like all Crassula species, Crassula arborescens uses Crassulacean Acid Metabolism (CAM), opening its stomata at night to fix carbon dioxide and closing them during the day to conserve water. This photosynthetic pathway is central to the species’ survival in the semi-arid Karoo.
Flowers and pollination
Inflorescences are terminal, dense, rounded thyrses composed of numerous dichasia. Individual flowers are small (approximately 10–15 mm across), star-shaped, with five petals ranging from white to pale pink, and are sweetly scented. The flowering period in the Southern Hemisphere is typically late autumn to winter (May–July); in Northern Hemisphere cultivation, expect blooms from November to January if the plant receives appropriate light and cool-night triggers. The flowers attract bees, wasps, flies, and butterflies. After pollination, the flowers turn papery brown and remain on the plant — a feature that has its own understated ornamental appeal. The very small, dust-like seeds are dispersed by wind.
Root system
The root system is shallow, enabling the plant to exploit light, brief rainfall events that wet only the upper soil layer — a critical survival strategy in the Karoo where rainfall is sparse and often evaporates quickly. In cultivation, this shallow rooting means the plant thrives in relatively shallow pots and is well suited to bonsai containers, but is particularly vulnerable to waterlogging.
The Two Subspecies
POWO recognises two subspecies of Crassula arborescens, which differ in leaf morphology and geographical range.
Crassula arborescens subsp. arborescens — the nominal subspecies and the form most commonly encountered in cultivation. Leaves are broadly orbicular (almost round), thick and fleshy, strongly pruinose (powdery blue-grey), and lie relatively flat. Distribution spans from the Hex River Valley through the Little and Central Karoo to KwaZulu-Natal and Eswatini.
Crassula arborescens subsp. undulatifolia Toelken — the “ripple jade” or “blue bird crassula”. Leaves are more elliptic (tongue-shaped rather than circular), thinner, less fleshy, distinctly undulate (wavy-margined), and strongly glaucous blue-grey with purple-red margins. The plant tends to be somewhat smaller and more compact, typically reaching 0.6–1 m. This subspecies was described by Toelken in 1975 and is restricted to the Klein Winterhoek Mountains of the Eastern Cape, growing on sandstone and shale-derived soils.
Subspecies undulatifolia is frequently mislabelled in the trade as Crassula ovata ‘Undulata’ or Crassula ovata var. undulatifolia — both of which are incorrect. It was also described by the Dutch horticulturist B.K. Boom in the journal Succulenta (1963, 1980) under the horticultural name Crassula portulacea ‘Blauwe Vogel’ (“Blue Bird”), and was long thought to be a hybrid between Crassula ovata and Crassula arborescens. It is not a hybrid but a valid geographic subspecies.
Crassula arborescens vs Crassula ovata — Key Differences
These are the two most widely grown tree-forming Crassula species and they are routinely confused by gardeners and retail outlets. Here is how to tell them apart:
Leaf shape. Crassula arborescens has almost circular (orbicular) leaves. Crassula ovata has clearly oval (elliptic to obovate) leaves.
Leaf surface. Crassula arborescens has a powdery, waxy bloom giving a matte, silvery blue-grey appearance. Crassula ovata has smooth, glossy, dark green leaves with no waxy bloom.
Leaf margins. Both species develop red-tinged margins in bright light, but the colouration is typically darker and more pronounced in Crassula arborescens.
Natural habitat. Crassula arborescens is a Karoo species from hot, dry, frost-prone valleys with 170–400 mm annual rainfall. Crassula ovata is an Eastern Cape and KwaZulu-Natal valley thicket species with 300–950 mm rainfall and milder winters. The two species do not naturally co-occur in the same vegetation type.
Cultivation differences. Crassula arborescens is somewhat more drought-tolerant, slightly more cold-hardy when dry, but slower-growing and generally considered slightly more demanding in cultivation — it is less tolerant of prolonged shade, stale air, and overwatering than the more forgiving Crassula ovata.
Cultivation Guide
Light requirements
Crassula arborescens is a full-sun species. In its native Karoo habitat it grows on exposed hillsides under intense, unfiltered sunlight for most of the day. In cultivation, provide the brightest possible position: a south-facing window (Northern Hemisphere) or an outdoor position in full sun during the warm months. Insufficient light is the single most common reason for poor performance indoors — the plant becomes etiolated, loses its compact shape, and the foliage loses its characteristic silvery bloom.
Unlike Crassula ovata, which tolerates moderate indoor light reasonably well, Crassula arborescens genuinely struggles in anything less than bright, direct light for at least five to six hours per day.
Temperature and hardiness
Given its Karoo origins, Crassula arborescens is adapted to significant temperature extremes — hot summers and cold, frosty winter nights — provided the substrate is dry. It is rated for USDA hardiness zones 9b to 11b. In the driest conditions, established plants can tolerate brief frost down to –3 °C to –5 °C without fatal damage, though leaf scorch and partial defoliation may occur.
However, this cold tolerance depends critically on substrate moisture. In wet winter conditions — typical of maritime climates in western Europe — frost damage begins at much milder temperatures, and root rot can occur even above freezing if the soil remains saturated. In such climates, the safest approach is to overwinter the plant in a bright, cool, frost-free location (5–10 °C) with minimal watering.
On the warm end, the species handles heat up to 40 °C without stress if airflow is adequate — it is more heat-tolerant than Crassula ovata.
Substrate
Drainage is paramount. As a Karoo species adapted to rocky, mineral-poor soils, Crassula arborescens requires a very free-draining substrate with a high mineral fraction. An effective mix is 60% mineral component (pumice, perlite, lava rock, coarse grit) with 40% or less organic matter (quality potting compost). Pure mineral mixes work well and reduce the risk of root rot in humid climates. Avoid peat-heavy substrates that retain moisture for extended periods. Terracotta pots are strongly preferred over plastic for their moisture-wicking properties.
Watering
Water even more sparingly than Crassula ovata. Allow the substrate to dry out completely between waterings — not just the surface, but the entire root zone. During the growing season (spring and summer), this typically means watering every 10–21 days depending on pot size, substrate composition, and ambient temperature. In winter, especially in cool conditions, reduce watering to once a month or less. In a cold greenhouse kept near freezing, watering can be suspended almost entirely for the winter months.
The species’ shallow root system is highly susceptible to rot in stagnant moisture. Overwatering is the primary killer, just as with Crassula ovata, but the silver jade is even less forgiving of wet feet because its Karoo habitat is significantly drier.
Fertilising
Minimal feeding is required. A dilute balanced fertiliser (half-strength) applied once a month from mid-spring to early autumn is sufficient. Excess nitrogen promotes soft, leggy growth that is vulnerable to rot and pests. No fertiliser during winter dormancy.
Repotting
Repot every two to four years in spring. Use a shallow pot — the species’ root system does not need depth, and a shallow, wide container provides stability for top-heavy specimens while allowing the substrate to dry quickly. When repotting, allow the cut roots to callus for several days before planting into dry substrate. Do not water for five to seven days after repotting.
Pruning
The species responds well to pruning. Pinch growing tips to encourage branching; remove crossing or unbalanced branches to maintain a compact, tree-like silhouette. Major cuts should be made in spring or early summer. Pruned material is easily propagated (see below). The species tolerates hard pruning and regenerates new growth from cut sites within a few weeks.
Propagation
Stem cuttings — the most reliable method. Select healthy stems of 5–10 cm, remove the lower leaves, allow the cut to callus for two to five days in a dry, shaded spot, and insert into slightly moist, well-draining substrate. Rooting typically occurs within two to four weeks. Spring and summer are optimal.
Leaf cuttings — twist off a healthy, mature leaf cleanly. Allow it to dry and callus for several days, then place it on the surface of dry succulent mix. A miniature plantlet with roots should emerge at the base within two to four weeks. Growth from leaf cuttings is slower than from stem cuttings.
Seed — possible but rarely practical. The dust-like seeds are sown on the surface of a sterile, well-draining mix, kept lightly moist at 21–24 °C. Germination is slow and erratic (three to six months), and seedling growth in the first year is very slow. Seed propagation is of interest primarily for genetic diversity or conservation purposes.
In the wild, vegetative reproduction dominates: broken branches root freely wherever they fall, and colonies can spread across entire hillsides by this mechanism alone.
Pests, Diseases, and Common Problems
Root and stem rot — the primary cause of mortality. Caused by overwatering, poor drainage, or a combination of both. Symptoms: soft, mushy stem base, discoloured translucent leaves, sour-smelling substrate. Treatment: remove from the pot, excise all rotten tissue, let cuts dry for several days, repot into fresh, dry mineral substrate.
Mealybugs — the most common pest. White cottony masses in leaf axils and at branch junctions. Treat by dabbing individual insects with isopropyl alcohol on a cotton swab. Persistent infestations may require insecticidal soap or neem oil applications.
Scale insects — flat, armoured brown insects on stems and leaf undersides. Remove manually with a soft brush or alcohol swab.
Powdery mildew — white fungal coating on leaves, favoured by poor airflow and humidity. Improve ventilation and reduce overhead watering. The pruinose leaf surface can make mildew harder to detect — inspect regularly.
Loss of waxy bloom — the distinctive powdery coating can be rubbed off by handling, rain splash, or overhead watering. While the bloom does regenerate slowly on new growth, handle the plant carefully and avoid wetting the foliage to preserve its ornamental appearance.
Etiolation — leggy, stretched growth with pale, widely spaced leaves, caused by insufficient light. This is the most common indoor cultural problem, and Crassula arborescens is more sensitive to low light than Crassula ovata. The only remedy is to provide significantly more light.
Toxicity
Like Crassula ovata, Crassula arborescens is considered toxic to cats, dogs, and horses. The ASPCA lists the genus Crassula as toxic to companion animals, with symptoms including vomiting, lethargy, and loss of coordination. The toxic compounds are suspected to be bufadienolides (cardiac glycosides), though the specific toxic principle in Crassula arborescens has not been conclusively identified. In humans, skin contact with the sap may cause mild irritation in sensitive individuals, but serious toxicity is not documented.
In its native South Africa, Crassula arborescens has traditional medicinal uses: the roots are eaten in Eswatini (where the plant is known as umchobozovithi), and preparations from the plant have been used in the treatment of epilepsy.
Cultural Significance
While Crassula arborescens does not carry the same feng shui associations as the jade plant (those are specifically attached to the glossy green foliage of Crassula ovata), it is nonetheless widely marketed as a “money tree” or “money plant” in the horticultural trade. Its silvery, coin-shaped leaves make the association irresistible to retailers.
The species is particularly valued in rock garden and xeriscape design in Mediterranean and semi-arid climates, where its sculptural form, drought tolerance, and distinctive colour provide year-round architectural interest. In South Africa, it is a popular garden plant for rocky embankments, gravel gardens, and large containers, often planted alongside Aloe ferox, Cotyledon orbiculata, and Crassula ovata to create a textured, low-water succulent landscape.
Crassula arborescens as Bonsai
Crassula arborescens is an excellent bonsai subject, arguably even more visually convincing than Crassula ovata for bonsai work, because its rounder, more coin-like leaves and its naturally gnarled, compact growth give it a more convincingly tree-like appearance in miniature. The styles best suited to this species are informal upright, clump, and twin-trunk, though group plantings and slanting styles are also achievable.
Shaping is accomplished primarily by clip-and-grow techniques. Wiring is possible but must be done with care: the branches are brittle and the bark marks easily. Allow the plant to dry slightly before wiring to reduce turgidity. New growth appears quickly after pruning (within one to three weeks), and the species thickens its trunk reliably over time when given adequate light, warmth, and growing room.
The main challenge for bonsai is the light requirement: Crassula arborescens bonsai kept in low indoor light will etiolate rapidly, losing the compact silhouette that makes bonsai convincing. An outdoor summer position in full sun, with winter protection indoors in a bright window or under supplemental lighting, yields the best results.
Frequently Asked Questions
How do I tell Crassula arborescens apart from Crassula ovata?
The easiest way is to look at the leaves. Crassula arborescens has almost round, blue-grey leaves covered in a powdery waxy bloom that gives them a matte, silvery appearance. Crassula ovata has oval, glossy, smooth, dark green leaves with no powdery coating. If the leaf is shiny green, it is Crassula ovata; if it is matte silver-grey with a dusty feel, it is Crassula arborescens.
Is Crassula arborescens harder to grow than Crassula ovata?
Crassula arborescens is slightly more demanding. It requires more light (full sun ideally), is less tolerant of overwatering, and grows somewhat more slowly. It is less forgiving of indoor conditions with poor light. However, in a bright, well-ventilated position with careful watering, it is not a difficult plant. It is actually more heat-tolerant and potentially more cold-hardy (when dry) than Crassula ovata, owing to its Karoo origins.
Can Crassula arborescens survive frost?
Yes, if the substrate is dry. Established plants in dry soil can tolerate brief frost down to –3 °C to –5 °C. In its native Little Karoo, it regularly endures 50 to 60 frost nights per year. However, prolonged cold combined with wet soil is fatal. In humid-winter climates, protect the plant from rain during the cold months or overwinter it indoors in a cool, bright, frost-free space.
What is Crassula arborescens subsp. undulatifolia?
It is a subspecies of Crassula arborescens with elliptic, wavy-edged (undulate), strongly blue-grey leaves and purple-red margins. It is sometimes sold as ‘Blue Bird’ or erroneously labelled as Crassula ovata ‘Undulata’. It is native to the Klein Winterhoek Mountains of the Eastern Cape and is slightly more compact than the nominal subspecies, typically reaching 0.6 to 1 m.
Is the silver jade plant toxic to pets?
Yes. Like all Crassula species, Crassula arborescens is listed as toxic to cats, dogs, and horses by the ASPCA. Ingestion can cause vomiting, lethargy, and loss of coordination. The toxic compounds are suspected to be bufadienolides, a type of cardiac glycoside. Keep the plant out of reach of curious pets.
Why is the waxy coating disappearing from my Crassula arborescens leaves?
The pruinose (powdery waxy) coating on the leaves is easily rubbed off by handling, rain, or overhead watering. Once removed from a particular leaf, it does not regenerate on that leaf — only new growth will display the full bloom. Handle the plant minimally, avoid touching the leaf surfaces, and water at the soil level rather than from above to preserve the silvery appearance.
How do I get my silver jade plant to flower?
Flowering requires a mature plant (typically several years old), strong direct light throughout the growing season, and a cool autumn period with shorter days and reduced watering to trigger bud initiation. Plants kept indoors in constant conditions rarely bloom because they never receive the necessary environmental signals — particularly the combination of bright light, cool nights, and water stress that mimics the onset of the Karoo dry season.
Sources and Further Reading
ASPCA Animal Poison Control — Jade Plant. aspca.org
Plants of the World Online (POWO), Royal Botanic Gardens, Kew — Crassula arborescens (Mill.) Willd. powo.science.kew.org
South African National Biodiversity Institute (SANBI), PlantZAfrica — Crassula arborescens. pza.sanbi.org
Smith, G.F., Figueiredo, E. & Mort, M.E. (2017). Taxonomy of the three arborescent crassulas, Crassula arborescens (Mill.) Willd. subsp. arborescens, C. arborescens subsp. undulatifolia Toelken, and Crassula ovata (Mill.) Druce (Crassulaceae) from southern Africa. Bradleya, 35: 87–105.
Tölken, H.R. (1985). Crassulaceae. In: Leistner, O.A. (ed.), Flora of Southern Africa, Vol. 14. Botanical Research Institute, Pretoria.
Hoare, D.B., Mucina, L., Rutherford, M.C., et al. (2006). Albany Thicket Biome. In: Mucina, L. & Rutherford, M.C. (eds.), The Vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. SANBI, Pretoria.
Eggli, U. (ed.) (2003). Illustrated Handbook of Succulent Plants: Crassulaceae. Springer, Berlin.
Rowley, G.D. (2003). Crassula: A Grower’s Guide. Cactus & Co. Libri, Venegono Superiore.
Court, D. (2010). Succulent Flora of Southern Africa. 3rd edition. Struik Nature, Cape Town.
Coates Palgrave, K. (2002). Trees of Southern Africa. Struik, Cape Town.