If you had to name one Crassula species grown primarily for its flowers, this would be it. While most cultivated crassulas are appreciated for their architectural foliage — the glossy ovals of Crassula ovata, the silvery coins of Crassula arborescens, the stacked beads of Crassula rupestris — Crassula perfoliata var. minor delivers something genuinely rare in the genus: a dense, spectacular, long-lasting display of vivid scarlet-red flowers that rise above the grey-green, sickle-shaped foliage in midsummer and last for up to a month. Known as the propeller plant, airplane plant, scarlet paintbrush, or sickle-leaf crassula, this variety has earned the Royal Horticultural Society’s Award of Garden Merit (AGM) — an honour shared by very few succulents — and remains one of the most visually striking Crassulaceae species in cultivation.
Taxonomy and Naming History — A Confusing Trail
The nomenclature of this plant has been turbulent, and understanding the name confusion is important because the same plant is sold under at least four different names in the trade.
The parent species Crassula perfoliata was described by Linnaeus in 1753. The plant treated here was long known as a separate species: Crassula falcata J.C.Wendl. (1798), and before that as Rochea falcata (J.C.Wendl.) DC. Toelken’s 1975 revision of the genus reduced it to a variety of Crassula perfoliata, as Crassula perfoliata var. falcata (J.C.Wendl.) Toelken. Rowley subsequently used the name Crassula perfoliata var. minor (Haw.) G.D.Rowley, based on Haworth’s earlier (1821) description. Both varietal names — var. falcata and var. minor — refer to the same plant. POWO currently lists var. falcata among the accepted infraspecific taxa, while SANBI’s PlantZAfrica uses var. minor. In practice, the plant is sold under all of the following names, which are synonymous:
- Crassula perfoliata var. minor (Haw.) G.D.Rowley
- Crassula perfoliata var. falcata (J.C.Wendl.) Toelken
- Crassula falcata J.C.Wendl. — still the most widely used name in the trade
- Rochea falcata (J.C.Wendl.) DC.
- Larochea falcata (J.C.Wendl.) Pers.
POWO recognises four varieties within Crassula perfoliata: var. perfoliata (the autonym), var. falcata (= var. minor, the propeller plant), var. coccinea (Sweet) G.D.Rowley (the red crassula, with erect red flowers and more compact, less falcate leaves), and var. heterotricha (Schinz) Toelken (with erect grey-green leaves and white flowers, distributed from tropical Africa to South Africa).
Etymology
The genus name Crassula derives from the Latin crassus (“thick, fat”). The species epithet perfoliata comes from the Latin per (“through”) and folia (“leaves”), describing the way the leaf bases clasp and surround the stem, making it appear as though the stem passes through the leaf tissue. The varietal epithet falcata means “sickle-shaped” in Latin (falx, “sickle”), describing the distinctively curved leaves. The alternative epithet minor means “smaller”, referring to this variety’s more compact size compared to the typical var. perfoliata.
The common name “propeller plant” describes the way the sickle-shaped leaves radiate outward in opposite directions from the stem, like the blades of a propeller. “Airplane plant” evokes the same imagery. “Scarlet paintbrush” refers to the vivid red flower clusters.
Natural Habitat and Distribution
Crassula perfoliata var. minor is endemic to South Africa. Its native range extends from the Groot Winterhoek mountains in the Western Cape eastward through Gqeberha (Port Elizabeth) to Mthatha (Umtata) in the Eastern Cape. It grows on quartzitic sandstone outcrops and cliffs — north, east, and west-facing aspects — along dry river valleys, in both fynbos and Albany Thicket biome vegetation. Altitude ranges from 250 to 1,000 m.
Associated species in its cliff habitat include Gasteria glomerata, Haworthia gracilis var. picturata, Haworthiopsis viscosa, Cotyledon orbiculata, Crassula rupestris, and Adromischus cristatus — a community of cliff-dwelling succulents typical of the Eastern Cape river valleys.
Climate across the natural range
Rainfall. The range spans the transition zone between winter-dominant rainfall in the west and year-round rainfall in the Eastern Cape. Annual totals are moderate, approximately 400–700 mm, distributed fairly evenly or with slight spring and autumn peaks.
Temperatures. The Eastern Cape cliff habitats where this variety grows experience warm summers (maxima 25–32 °C) and mild winters (minima 5–10 °C at the coast, occasionally colder inland). Frost is uncommon in the coastal cliff habitats but possible further inland. The species is rated for USDA hardiness zones 9b to 11b, tolerating brief lows to approximately –3 °C in dry conditions.
The cliff habitat provides excellent drainage (water runs off immediately), good airflow, and a degree of shelter from extreme wind and temperature — conditions that should be replicated in cultivation.
Botanical Description
Growth habit and stem
Crassula perfoliata var. minor is an erect, sparingly branched perennial succulent, typically growing as a single stem that offsets at the base to produce a small clump of one to several rosettes. The stems reach 30–60 cm tall when in flower (up to 1.2 m in some reports, but usually under 60 cm in cultivation). The stems are fleshy, becoming slightly woody at the base with age. The growth habit is upright and somewhat columnar — quite different from the sprawling, mat-forming habit of Crassula capitella or the trailing stems of Crassula perforata.
Leaves
The leaves are the plant’s vegetative signature: oblong-lanceolate, distinctly sickle-shaped (falcate), laterally compressed, ascending to spreading, arranged in opposite overlapping pairs along the stem. Individual leaves measure up to 100 mm long and 28 mm wide, are thick and succulent, with a flat upper surface channelled at the base. The colour is grey-green to glaucous, often with red or purple spots or markings, and the surface is covered in fine, rounded papillae that give it a velvety texture. The leaf margins bear minute teeth — detectable by touch rather than sight, producing a sensation similar to running a finger along a closed zipper. Older leaves are persistent on the stems, remaining attached even as they dry.
The overall foliage effect is bold and sculptural — grey, matte, curved, and geometric — providing strong year-round interest even before the spectacular flowers appear.
Flowers — the main event
The inflorescence is a dense, rounded to flat-topped cyme (thyrse) borne on an elongated peduncle up to 100 mm above the foliage. The flower head is 8–12 cm across and composed of many tiny individual flowers. This is where Crassula perfoliata var. minor distinguishes itself from the rest of the genus: the flowers are a brilliant scarlet-red to salmon-red — not the white or pale pink typical of most crassulas. They open slowly over several weeks, and the display lasts for nearly a month at full bloom. The flowers are mildly fragrant, with a cinnamon-like scent that attracts butterflies and other pollinators.
Flowering occurs in summer (November–February in the Southern Hemisphere; approximately June–August in the Northern Hemisphere, typically peaking in July–August in California and Mediterranean-climate gardens). The combination of vivid red flowers above grey-green foliage is visually spectacular and unlike anything else in the Crassula genus — the reason for the RHS AGM and the plant’s enduring popularity.
Root system
Shallow and fibrous, typical of a cliff-dwelling species adapted to thin soil over rock.
Crassula perfoliata vs Crassula perforata — Clearing the Confusion
These two names differ by a single letter and are routinely confused by beginners. They refer to completely different plants:
Crassula perfoliata (this article) — erect, unbranched stems with large, sickle-shaped, grey-green leaves and spectacular scarlet-red flowers in summer. The name means “with leaves that the stem passes through”.
Crassula perforata — a small, scrambling plant with triangular, stacked leaves on thin, trailing stems, cream-yellow flowers in spring. The name means “pierced” (the stem appears to pierce the fused leaf pairs). Common name: string of buttons.
If the plant has big, grey, curved, sickle-shaped leaves and red flowers, it is Crassula perfoliata. If it has small, triangular, stacked green leaves on thin trailing stems, it is Crassula perforata.
Cultivation Guide
Light requirements
Bright light with several hours of direct sun. In its native cliff habitat, Crassula perfoliata var. minor grows on north, east, and west-facing rock faces — positions that receive strong but not necessarily all-day sun. In cultivation, morning sun plus bright afternoon light works well. Full midday sun in very hot climates (above 35 °C) can scorch the leaves, particularly during the hottest summer months. Insufficient light produces etiolated, weak stems that topple under their own weight.
Temperature and hardiness
USDA hardiness zones 9b to 11b. Tolerates brief frost to approximately –3 °C in dry conditions. Not suited to prolonged freezing. In frost-prone climates, grow in containers and overwinter in a bright, frost-free space. The species handles moderate summer heat (30–35 °C) without difficulty but does not appreciate sustained temperatures above 38 °C.
Substrate
Well-draining, gritty mix. As a cliff-dweller adapted to thin, quartzitic sandstone-derived soil, it demands excellent drainage. A 50:50 mineral (pumice, perlite, coarse grit) to organic (potting compost) mix is effective. Terracotta pots are preferred.
Watering
Water moderately during the growing season, allowing the substrate to dry between waterings. The leaves become very turgid during wet periods and flatten and develop reddish tints during dry spells — a visual cue for watering. During winter, reduce watering significantly. Overwatering causes root rot, as with all crassulas.
Fertilising
Feed with a dilute balanced fertiliser at half strength, monthly during spring and summer. The species benefits from light feeding when developing flower buds. No fertiliser in winter.
After flowering
Remove spent flower heads to maintain vigour and encourage a bushy habit. The plant is not strictly monocarpic like Crassula capitella — the rosette that flowers does not necessarily die, though it may become leggy or decline over time. New offsets from the base typically replace aging stems. After several years, stems can become bare and leggy at the base; at this point, take cuttings from the top, re-root them, and start fresh.
Propagation
Stem cuttings — the primary method. Take cuttings of 10–15 cm, remove the lower leaves, allow the cut to callus for several days, and insert into well-draining substrate. Rooting takes three to six weeks — somewhat slower than for smaller-leaved Crassula species.
Leaf cuttings — individual leaves can be detached and rooted. Place on moist substrate; a plantlet emerges at the base within several weeks. Viable but slower than stem cuttings.
Offsets — the plant produces basal offsets that can be separated and potted individually at repotting time.
Seed — possible but slow. Wind-dispersed seeds are very fine. Sow on the surface of sterile, well-draining mix in spring.
Pests, Diseases, and Common Problems
Root and stem rot — the standard risk. Prevention: well-draining substrate, infrequent watering, good airflow.
Mealybugs — the most common pest. They hide in the tight spaces between overlapping leaf pairs and at the base of the rosette. Treat with isopropyl alcohol on a fine brush.
Leggy stems — after several years, stems become bare at the base and top-heavy. This is not a disease but the natural growth pattern. Take cuttings from the healthy upper portion and restart.
Toxicity
The toxicity status of Crassula perfoliata var. minor is not entirely clear. The ASPCA lists the genus Crassula broadly as toxic to pets (cats, dogs, horses), with bufadienolides as the suspected compounds. However, in its native South Africa, the dried, crushed roots of Crassula perfoliata have traditional medicinal use for wound healing, suggesting a different toxicological profile from the more definitively toxic Crassula ovata. As a precaution, treat this plant as potentially toxic to pets and keep it out of reach of curious animals.
The Other Varieties of Crassula perfoliata
For completeness, the three other varieties of Crassula perfoliata are:
Var. perfoliata — the autonym. Larger than var. minor, with erect, less strongly falcate leaves and white to pink flowers. Less commonly cultivated.
Var. coccinea (Sweet) G.D.Rowley — the red crassula. Erect, compact plant with bright red tubular flowers. Formerly known as Crassula coccinea, it was historically important as one of the first South African succulents to be cultivated in Europe (early 1700s). It is the parent of the now-obsolete genus Rochea.
Var. heterotricha (Schinz) Toelken — up to 40 cm tall with erect grey-green leaves and white flowers up to 7 mm long. Winter-flowering. Distribution extends from tropical Africa south to the northeastern Eastern Cape — a much wider range than var. minor. Grows on the escarpment and in river valley ledges.
Frequently Asked Questions
Is Crassula falcata the same as Crassula perfoliata var. minor?
Yes. Crassula falcata J.C.Wendl. (1798) is the old, widely used name for the propeller plant. Modern taxonomic revisions place it as a variety of Crassula perfoliata, either as var. falcata (Toelken’s name, used by POWO) or var. minor (Rowley’s name, used by SANBI). All three names — Crassula falcata, Crassula perfoliata var. falcata, and Crassula perfoliata var. minor — refer to the same plant.
What is the difference between Crassula perfoliata and Crassula perforata?
Despite their nearly identical names, these are completely different plants. Crassula perfoliata (the propeller plant) has large, grey-green, sickle-shaped leaves and spectacular scarlet-red flowers. Crassula perforata (the string of buttons) is a small, trailing plant with tiny, triangular, stacked green leaves and cream-yellow flowers. The one-letter difference in the name causes constant confusion in the trade.
How do I get my propeller plant to flower?
Flowering requires a mature plant (typically at least two to three years old), bright light with several hours of direct sun, and a cool-to-mild winter rest period with reduced watering. Plants kept in low light indoors rarely flower. An outdoor summer position in bright light with good airflow is the best recipe. Light feeding during spring as flower buds develop can also help. Once established, the species flowers reliably each summer.
Does the propeller plant die after flowering?
Not usually. Unlike Crassula capitella, which is monocarpic (the rosette dies after flowering), Crassula perfoliata var. minor typically survives flowering. However, the flowering stem may become leggy or decline gradually over time, and new basal offsets eventually replace it. Remove spent flower heads promptly to maintain vigour, and take cuttings periodically as insurance.
Is the propeller plant toxic to cats?
The ASPCA lists the genus Crassula as toxic to cats, dogs, and horses, so Crassula perfoliata var. minor should be treated as potentially toxic. Ingestion may cause vomiting, lethargy, and loss of coordination. Keep out of reach of pets as a precaution.
Sources and Further Reading
ASPCA Animal Poison Control — Jade Plant. aspca.org
Plants of the World Online (POWO), Royal Botanic Gardens, Kew — Crassula perfoliata L. powo.science.kew.org
South African National Biodiversity Institute (SANBI), PlantZAfrica — Crassula perfoliata var. minor. Van Jaarsveld, E. (2008). pza.sanbi.org
Tölken, H.R. (1975). A Revision of the Genus Crassula in Southern Africa. Journal of South African Botany, 41.
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.
Court, D. (2010). Succulent Flora of Southern Africa. 3rd edition. Struik Nature, Cape Town.
Royal Horticultural Society — Award of Garden Merit listings.