If you think all crassulas are evergreen shrublets with opposite pairs of fleshy leaves, Crassula umbella will upend every expectation. This extraordinary species in the genus Crassula (family Crassulaceae) is a tuberous geophyte — a plant that retreats underground into a spherical tuber during its dormant season, then sends up ephemeral stems bearing one or two pairs of leaves that are fused into a single, round, raised-edged disc around the stem, forming a structure that looks uncannily like an inverted wine glass or a shallow cup held aloft on a stalk. The cultivar ‘Wine Cup’, with its bright green, perfectly circular leaf-disc and elegant raised rim, has become one of the most sought-after and photographed rare succulents in the collector market — a plant that regularly goes viral on social media and commands premium prices as dormant tubers on specialist platforms.
Taxonomy and Naming History
Crassula umbella was described by Nikolaus von Jacquin. The accepted name is Crassula umbella Jacq. POWO classifies it as a succulent tuberous geophyte growing primarily in the subtropical biome.
The species belongs to Crassula section Petrogeton, a group of eight geophytic species with annual herbaceous branches arising from a tuber — all restricted to winter-rainfall areas of South Africa except for one summer-rainfall outlier. This section represents a radically different life strategy from the evergreen, shrubby species that dominate the rest of the genus in cultivation.
Principal synonyms include:
- Petrogeton umbella (Jacq.) Eckl. & Zeyh. (1837)
- Septas umbella Haw. (1812)
- Crassula flabellifolia Harv. (1862)
- Crassula loriformis Schönland & Baker f. (1902)
- Crassula weissii N.E.Br. (1908)
Beware of confusion: Crassula umbella (the wine cup, a tuberous geophyte) must not be confused with Crassula umbellata Thunb. — a completely different species, a tiny annual described as the smallest succulent in the world, forming flat discs only 2–6 mm high in exposed sandy soils.
Etymology
The genus name Crassula derives from the Latin crassus (“thick, fat”). The specific epithet umbella is Latin for “sunshade, parasol, or umbrella”, describing the way the leaves are fused into a round disc around the stem, creating an umbrella-like structure. The cultivar name ‘Wine Cup’ refers to the raised rim of the leaf disc, which gives it the appearance of a shallow wine glass or chalice.
Natural Habitat and Distribution
Crassula umbella is endemic to the Cape Provinces of South Africa. Its range extends from the Richtersveld in the northwest through the western Karoo and Little Karoo to Humansdorp in the Eastern Cape. It is assessed as Least Concern, being widespread and not in decline.
The species grows on south-facing aspects of sheltered, gravelly slopes — typically under shrubs or, more characteristically, under overhanging rocks. This preference for sheltered, shaded, south-facing (cool) positions is consistent with its geophytic life strategy: the tuber survives the hot, dry summer underground, protected by rock or shrub cover, and the aerial parts emerge during the cool, wet winter months when moisture and moderate light are available.
Climate across the natural range
Rainfall. The species occurs squarely in the winter-rainfall zone, with annual totals of 150–400 mm concentrated between May and August. Summers are hot and dry — the period during which the tuber is dormant underground.
Temperatures. Summer maxima in the Karoo interior reach 35–42 °C, but the south-facing, rock-sheltered microsites where the species grows are significantly cooler and more buffered than the surrounding landscape. Winter minima fall to 2–7 °C, with occasional frost possible in the more inland parts of the range. USDA zones 9a to 11b.
Botanical Description
The tuber
At the heart of Crassula umbella is a spherical underground tuber — the permanent organ that stores water and energy through the long, hot, dry summer dormancy. The aerial stems and leaves are temporary structures produced annually during the winter growing season and dying back as summer approaches. This geophytic life cycle is radically different from the evergreen persistence of species like Crassula ovata or Crassula arborescens, and is the reason the plant is sometimes sold as a “bulb” on specialist platforms (though technically a tuber, not a true bulb).
Stems and leaves — the wine cup
From the tuber, erect, unbranched stems emerge during the cool season, typically reaching 15–25 cm tall (up to 40 cm according to some sources). Each stem bears one or two pairs of opposite, yellowish-green leaves. Here is the species’ defining feature: the leaves of each pair are transversely depressed-obovate or — in the most spectacular forms — fully fused into a single, round, disc-like structure encircling the stem. In the cultivar ‘Wine Cup’, this disc can reach up to 15 cm in diameter, with the margins raised upward to form a shallow, cup-like rim. The effect is a perfectly circular, bright green saucer or shallow chalice held horizontally on a vertical stalk — an utterly unique form in the plant world.
The degree of leaf fusion varies between populations and between cultivated forms. In some wild plants, the leaves are merely broadly kidney-shaped and only partially fused at the base; in ‘Wine Cup’, the fusion is nearly complete, producing the clean, unbroken disc that has made the cultivar famous.
Flowers
Flowers are produced in a terminal, elongated thyrse on a stalk emerging from the centre of the leaf disc. Individual flowers are small, star-shaped, white to yellowish-green, approximately 10 mm across. Flowering occurs in winter to early spring (July–September in the Southern Hemisphere). After flowering and seed set, the aerial parts gradually die back as the plant enters summer dormancy.
The Cultivar ‘Wine Cup’
Crassula umbella ‘Wine Cup’ is the form that has captured the collector market. Selected for its particularly complete leaf fusion, its bright green colour, and its cleanly raised disc margin, it is the form most frequently photographed, shared on social media, and sold on platforms like Etsy, usually as dormant tubers.
Expect to pay a premium for this cultivar — it is slow-growing, difficult to propagate in commercial quantities, and remains genuinely rare compared to mass-market succulents. Its viral popularity far outstrips its supply, which sustains high demand and collector-level pricing.
Cultivation Guide — A Different Approach
Growing Crassula umbella requires a fundamentally different mindset from growing evergreen crassulas. This is a winter-growing, summer-dormant geophyte — treat it like a winter-rainfall bulb, not like a houseplant.
The annual cycle
Autumn (September–November in the Northern Hemisphere): As temperatures cool and day length shortens, the tuber breaks dormancy. Begin watering lightly to trigger growth. Stems and leaves emerge over several weeks.
Winter through spring (December–April): The active growing and flowering season. Water moderately, allowing the substrate to dry between waterings but not leaving it bone-dry for extended periods. Provide bright, indirect light — the species grows under rocks and shrubs in habitat, not in full sun.
Late spring to summer (May–August): As temperatures rise and the leaves begin to yellow and wither, reduce watering progressively and stop entirely once the aerial parts have died back. The tuber is now dormant underground. Keep the pot completely dry in a cool, shaded position through the summer. Do not water a dormant tuber — this is the fastest way to cause rot.
Light requirements
Bright, indirect light during the growing season. The species grows under overhanging rocks and shrubs in habitat — it is adapted to filtered light, not full, unshaded sun. Direct midday sun can scorch the thin, fused leaves.
Substrate
Very well-drained, gritty, mineral-heavy mix — 70% mineral (pumice, perlite, coarse sand, fine gravel) with 30% organic. The tuber must never sit in stagnant moisture. A shallow pot with large drainage holes is essential.
Temperature
USDA zones 9a to 11b. Tolerates brief frost to approximately –6 °C. Keep cool during the growing season (10–20 °C is ideal); during summer dormancy, warmth is fine as long as the tuber is dry.
Propagation
Seed — the primary method for producing new plants. Very fine, wind-dispersed seeds. Sow on the surface of sterile, well-draining mineral substrate in autumn (the start of the growing season). Keep moist and shaded. Germination is slow and seedling growth is very slow — expect to wait several years before a seedling produces its first characteristic fused-leaf disc.
Division — mature tubers may occasionally offset. Offsets can be separated and potted individually during the dormant period.
Leaf/stem cuttings — theoretically possible but rarely practical for a tuberous geophyte. The aerial parts are temporary and do not produce adventitious roots with the same ease as evergreen Crassula species.
Pests and Diseases
Mealybugs can affect the aerial parts during the growing season. Root rot from overwatering — particularly during summer dormancy — is the primary killer. The tuber is vulnerable to fungal infection if stored in damp conditions.
Toxicity
As with other Crassula species, treat as potentially toxic to cats, dogs, and horses (ASPCA genus-level listing).
Frequently Asked Questions
Why did my Crassula umbella die back in summer?
It did not die — it went dormant. Crassula umbella is a tuberous geophyte that naturally dies back to an underground tuber during the hot, dry summer. The aerial stems and leaves are temporary structures produced during the cool winter growing season. Stop watering entirely when the leaves begin to wither in late spring, and keep the tuber dry through summer. Growth will resume when temperatures cool in autumn.
Is Crassula umbella the same as Crassula umbellata?
No — they are completely different species despite the near-identical names. Crassula umbella Jacq. is a tuberous geophyte with large, fused, cup-shaped leaves (the “wine cup”). Crassula umbellata Thunb. is a tiny annual, described as the smallest succulent in the world, forming flat discs only 2–6 mm high. The one-letter difference causes confusion, but the plants have nothing in common visually.
How do I water a dormant Crassula umbella tuber?
You do not. During summer dormancy (when the aerial parts have died back), the tuber must be kept completely dry. Watering a dormant tuber is the fastest way to cause fatal rot. Store the pot in a cool, dry, shaded position and do not water until autumn, when you begin lightly moistening the substrate to trigger the new growing season.
Where can I buy Crassula umbella ‘Wine Cup’?
Crassula umbella ‘Wine Cup’ is a rare collector’s plant not typically available in mainstream garden centres. It is most commonly sold as dormant tubers on specialist succulent platforms, Etsy, and through succulent collector networks. Expect to pay collector-level prices — the plant’s viral popularity far outstrips commercial supply. When purchasing, buy from reputable sellers and be prepared for slow growth: it takes several years from tuber to a specimen with a fully developed wine-cup disc.
Sources and Further Reading
- Plants of the World Online (POWO), Royal Botanic Gardens, Kew — Crassula umbella Jacq. powo.science.kew.org
- Pacific Bulb Society — Crassula (section Petrogeton). pacificbulbsociety.org
- Tölken, H.R. (1985). Crassulaceae. In: Leistner, O.A. (ed.), Flora of Southern Africa, Vol. 14. Botanical Research Institute, 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.
- ASPCA Animal Poison Control — Jade Plant. aspca.org