Ice Plant

What Is Ice Plant?

Ice plant is a genus of low, mat-forming succulents, Delosperma, grown as hardy ground covers for their bright daisy-like flowers. Its leaves are covered in tiny bladder-like hairs that make them glisten ^{18Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →}.

Delosperma belongs to the ice plant family, Aizoaceae, and is native to Africa and the Arabian Peninsula ^{18Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →}. The garden species come from the high grasslands and cliffs of South Africa and Lesotho ^{16,17Reference 16Plants of the World Online · 2026Delosperma cooperi (Hook.f.) L.Bolus — native range and habitat — species databaseView study →Reference 17South African National Biodiversity InstDelosperma nubigenum — description, distribution and habitat — species databaseView study →}.

Kanna (Sceletium tortuosum) belongs to the same family, and its mesembrine alkaloids have been studied for anxiety, mood and cognition ^{2Reference 2Krstenansky JL · 2017ReviewMesembrine alkaloids: review of their occurrence, chemistry, and pharmacology — reviewView study →}. A 1998 survey that screened Delosperma with other genera of the family found alkaloid levels extremely low outside Sceletium ^{1Reference 1Smith MT et al. · 1998The distribution of mesembrine alkaloids in selected taxa of the Mesembryanthemaceae and their modification in the Sceletium-derived ‘Kougoed’ — chemical surveyView study →}.

The name “ice plant” is also used for the crystalline ice plant (Mesembryanthemum crystallinum) and for Carpobrotus, which are different plants.

How Is Ice Plant Used?

Ice plant is grown as a ground cover, as edging, in rock gardens and in containers ^{18Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →}.

Its herbal interest comes from its kinship with kanna. No medicinal preparation of Delosperma has been developed.

Indications

• Anxiety and low mood [aerial parts] ⚠Caution: This rests on its relative kanna. No study has tested Delosperma, and the one survey that screened it found alkaloid levels extremely low ¹.

Botany

Ice plant is a low, creeping succulent in the ice plant family (Aizoaceae), the same family as kanna ^{1,18Reference 1Smith MT et al. · 1998The distribution of mesembrine alkaloids in selected taxa of the Mesembryanthemaceae and their modification in the Sceletium-derived ‘Kougoed’ — chemical surveyView study →Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →}. It spreads into mats 30–60 cm wide ^{18,19Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →Reference 19North Carolina Extension Gardener Plant Delosperma cooperi — description, size and origin — species databaseView study →}.

The leaves are fleshy, glossy and nearly cylindrical. Tiny bladder-like hairs on their surface reflect light and make them glisten ^{18,19Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →Reference 19North Carolina Extension Gardener Plant Delosperma cooperi — description, size and origin — species databaseView study →}.

The flowers are daisy-like, 2.5–5 cm across, and come in many colours ^{18Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →}. They bloom from early summer into autumn ^{18Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →}.

Two species are common in gardens. Delosperma cooperi grows 8–15 cm tall and has purplish-pink flowers ^{19Reference 19North Carolina Extension Gardener Plant Delosperma cooperi — description, size and origin — species databaseView study →}. D. nubigenum is a lower plant with bright yellow flowers and flat, oval leaves that turn purplish in the dry season ^{17Reference 17South African National Biodiversity InstDelosperma nubigenum — description, distribution and habitat — species databaseView study →}.

Distribution

The genus Delosperma is native to Africa and the Arabian Peninsula ^{18Reference 18North Carolina Extension Gardener Plant Delosperma — genus description, native range and cultivation — species databaseView study →}.

Delosperma cooperi grows wild from the Free State of South Africa to Lesotho, in highveld and Drakensberg grassland ^{16Reference 16Plants of the World Online · 2026Delosperma cooperi (Hook.f.) L.Bolus — native range and habitat — species databaseView study →}.

Delosperma nubigenum is endemic to the Drakensberg and the highlands of Lesotho, at 2,500–3,400 m. It grows on basalt cliffs, rooted in crevices and on ledges ^{17Reference 17South African National Biodiversity InstDelosperma nubigenum — description, distribution and habitat — species databaseView study →}.

Growing Conditions

Cultivation snapshot for Ice Plant

LifeperennialZoneUSDA 5–9

• Full sun is essential — both flowering and compact growth fall off in shade.
• Give it sharp, fast-draining soil (sandy, gritty or rocky); it tolerates lean, poor ground but not wet feet, and winter wet — not cold — is the usual killer.
• Genuinely cold-hardy for a succulent (roughly USDA zones 5–9, some selections to zone 4), making it a rare frost-tough mesemb.
• Very easy to propagate: trailing stems root where they touch the ground, and cuttings or divisions establish readily; drought-tolerant once settled.

Grow it yourself

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How to growComing soon

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Pharmacology & Research

No pharmacological study of Delosperma has been published, and no trial of any species in the genus has been registered.

Interest in the genus comes from its family’s mesembrine alkaloids. In kanna these alkaloids block serotonin reuptake and inhibit PDE4, and a standardised kanna extract (Zembrin®) has been tested in small human trials ^{3,4,5,10Reference 3Harvey AL et al. · 2011In vitroPharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids — in vitro receptor/enzyme panelView study →Reference 4Reay J et al. · 2020RCTSceletium tortuosum (Zembrin®) ameliorates experimentally induced anxiety in healthy volunteers — randomised, double-blind, placebo-controlled trialView study →Reference 5Terburg D et al. · 2013RCTAcute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala — randomised controlled fMRI trialView study →Reference 10Chiu S et al. · 2014RCTProof-of-concept randomized controlled study of cognition effects of the proprietary extract Sceletium tortuosum (Zembrin) targeting phosphodiesterase-4 in cognitively healthy subjects — randomised, double-blind, placebo-controlled crossover trial (NCT01805518)View study →}.

A 1998 survey of 20 species in nine genera of the family found alkaloid levels extremely low in every genus other than Sceletium, with Aptenia the only one to contain them in any significant amount. Delosperma was among the genera screened ^{1Reference 1Smith MT et al. · 1998The distribution of mesembrine alkaloids in selected taxa of the Mesembryanthemaceae and their modification in the Sceletium-derived ‘Kougoed’ — chemical surveyView study →}.

1. Anxiolytic & Mood Support

In a standardised Sceletium extract (Zembrin®), mesembrine was the most active alkaloid at the serotonin transporter, and mesembrenone acted on both the serotonin transporter and PDE4 ^{3Reference 3Harvey AL et al. · 2011In vitroPharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids — in vitro receptor/enzyme panelView study →}. A high-mesembrine extract also acted as a monoamine-releasing agent in cell models ^{12Reference 12Coetzee DD et al. · 2016In vitroHigh-mesembrine Sceletium extract (Trimesemine™) is a monoamine releasing agent, rather than only a selective serotonin reuptake inhibitor — in vitro cell modelView study →}.

In healthy volunteers, a single 25 mg dose of Zembrin® was tested in two placebo-controlled studies. It had no effect on mood during a multitasking stressor. Before a simulated public-speaking task, subjective anxiety was lower with Zembrin®, and heart rate responded differently ^{4Reference 4Reay J et al. · 2020RCTSceletium tortuosum (Zembrin®) ameliorates experimentally induced anxiety in healthy volunteers — randomised, double-blind, placebo-controlled trialView study →}.

In a crossover fMRI study of 16 healthy people, a single 25 mg dose reduced amygdala reactivity to fearful faces and reduced amygdala–hypothalamus coupling ^{5Reference 5Terburg D et al. · 2013RCTAcute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala — randomised controlled fMRI trialView study →}.

In zebrafish larvae, mesembrine accounted for the anxiety-lowering effect of the whole extract. The antidepressant-like effect needed the whole extract, and no single alkaloid reproduced it ^{6Reference 6Gericke J et al. · 2024AnimalSceletium tortuosum-derived mesembrine significantly contributes to the anxiolytic effect of Zembrin®, but its anti-depressant effect may require synergy of multiple constituents — in vivo zebrafishView study →}.

Earlier zebrafish work found all four main alkaloids lowered anxiety-like behaviour, most strongly mesembrenone and mesembranol ^{7Reference 7Maphanga VB et al. · 2022AnimalMesembryanthemum tortuosum L. alkaloids modify anxiety-like behaviour in a zebrafish model — in vivo zebrafishView study →}. In rats, mesembrine showed pain-relieving activity and a Sceletium fraction showed antidepressant activity along with ataxia ^{8Reference 8Loria MJ et al. · 2014AnimalEffects of Sceletium tortuosum in rats — animal behavioural modelView study →}.

Gap: no Delosperma study of any kind; the human data are single-dose, small and specific to Sceletium.

2. Cognitive & Attentional Support

In a crossover trial in 21 cognitively healthy adults, 25 mg a day of Zembrin® for three weeks improved cognitive set-flexibility and executive function compared with placebo. The authors linked the effect to PDE4–cAMP–CREB signalling ^{10Reference 10Chiu S et al. · 2014RCTProof-of-concept randomized controlled study of cognition effects of the proprietary extract Sceletium tortuosum (Zembrin) targeting phosphodiesterase-4 in cognitively healthy subjects — randomised, double-blind, placebo-controlled crossover trial (NCT01805518)View study →}.

Mesembrenone is the alkaloid with the stronger PDE4-inhibiting activity ^{2,3Reference 2Krstenansky JL · 2017ReviewMesembrine alkaloids: review of their occurrence, chemistry, and pharmacology — reviewView study →Reference 3Harvey AL et al. · 2011In vitroPharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids — in vitro receptor/enzyme panelView study →}.

In rat hippocampal tissue, Zembrin® and its four main alkaloids (mesembrine, mesembrenone, mesembrenol and mesembranol) reduced electrical excitability ^{11Reference 11Dimpfel W et al. · 2018In vitroEffect of Zembrin® and four of its alkaloid constituents on electric excitability of the rat hippocampus — ex vivo/in vitroView study →}.

In male rats under chronic mild stress, Zembrin® reduced anhedonia- and anxiety-like behaviour, and isolated mesembrine gave a transient reduction in anhedonia ^{9Reference 9Gericke J et al. · 2025AnimalNeuro-inflammatory and behavioral changes are selectively reversed by Sceletium tortuosum (Zembrin®) and mesembrine in male rats subjected to unpredictable chronic mild stress — animal modelView study →}.

Gap: one small human trial, of one company’s extract; no Delosperma data.

Mechanisms

Mesembrine and mesembrenone have been studied for blocking the serotonin transporter and for inhibiting PDE4, the enzyme that breaks down cAMP ^{3Reference 3Harvey AL et al. · 2011In vitroPharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids — in vitro receptor/enzyme panelView study →}. Mesembrenol and mesembranol have been studied for their effects on excitatory transmission in the hippocampus ^{11Reference 11Dimpfel W et al. · 2018In vitroEffect of Zembrin® and four of its alkaloid constituents on electric excitability of the rat hippocampus — ex vivo/in vitroView study →}.

All of this work used kanna or its purified alkaloids.

Clinical Trials

No clinical trial of any Delosperma species has been registered. The registered trials in this chemical space, including the Zembrin® cognition study (NCT01805518) ^{10Reference 10Chiu S et al. · 2014RCTProof-of-concept randomized controlled study of cognition effects of the proprietary extract Sceletium tortuosum (Zembrin) targeting phosphodiesterase-4 in cognitively healthy subjects — randomised, double-blind, placebo-controlled crossover trial (NCT01805518)View study →}, all tested Sceletium tortuosum.

Last checked: July 2026.

Phytochemistry

The compounds of interest are the mesembrine-type alkaloids, mesembrine, mesembrenone, mesembrenol and mesembranol. They are the main active alkaloids of kanna ^{2Reference 2Krstenansky JL · 2017ReviewMesembrine alkaloids: review of their occurrence, chemistry, and pharmacology — reviewView study →}.

A 1998 survey screened 20 species from nine genera of the family, Delosperma among them. Alkaloid levels were extremely low in every genus except Sceletium, and Aptenia was the only other genus to contain them in any significant amount ^{1Reference 1Smith MT et al. · 1998The distribution of mesembrine alkaloids in selected taxa of the Mesembryanthemaceae and their modification in the Sceletium-derived ‘Kougoed’ — chemical surveyView study →}.

No amounts have been published for any Delosperma species.

Constituent Summary

Mesembrine-type alkaloids of the family; levels in Delosperma are extremely low ^{1Reference 1Smith MT et al. · 1998The distribution of mesembrine alkaloids in selected taxa of the Mesembryanthemaceae and their modification in the Sceletium-derived ‘Kougoed’ — chemical surveyView study →}.

Dosage

Delosperma has no established dose. The human trials of kanna used 25 mg a day of the standardised Sceletium extract Zembrin® ^{4,10Reference 4Reay J et al. · 2020RCTSceletium tortuosum (Zembrin®) ameliorates experimentally induced anxiety in healthy volunteers — randomised, double-blind, placebo-controlled trialView study →Reference 10Chiu S et al. · 2014RCTProof-of-concept randomized controlled study of cognition effects of the proprietary extract Sceletium tortuosum (Zembrin) targeting phosphodiesterase-4 in cognitively healthy subjects — randomised, double-blind, placebo-controlled crossover trial (NCT01805518)View study →}, a different plant and preparation.

Safety & Pregnancy

Ice plant is grown in gardens, and no safety concern has been reported from that use. No human safety data exist for any Delosperma species.

Full Safety Detail

No direct data. No clinical, toxicological or case-report literature exists for any Delosperma species, and no pharmacopoeia covers the genus.

Serotonergic drugs. The family’s mesembrine-type alkaloids block serotonin reuptake and release monoamines ^{3,12Reference 3Harvey AL et al. · 2011In vitroPharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids — in vitro receptor/enzyme panelView study →Reference 12Coetzee DD et al. · 2016In vitroHigh-mesembrine Sceletium extract (Trimesemine™) is a monoamine releasing agent, rather than only a selective serotonin reuptake inhibitor — in vitro cell modelView study →}. If a Delosperma preparation carried meaningful amounts, the same caution as for kanna would apply: avoid combining it with SSRIs, SNRIs, MAOIs, triptans or other serotonergic drugs. This is inferred from kanna’s pharmacology, and the alkaloid levels found in Delosperma are extremely low ^{1Reference 1Smith MT et al. · 1998The distribution of mesembrine alkaloids in selected taxa of the Mesembryanthemaceae and their modification in the Sceletium-derived ‘Kougoed’ — chemical surveyView study →}.

The kanna data. A standardised Sceletium extract had no adverse effects in rats up to 600 mg/kg a day for 90 days, and 8 or 25 mg a day was well tolerated for three months in healthy adults ^{13,14Reference 13Nell H et al. · 2013RCTA randomized, double-blind, parallel-group, placebo-controlled trial of extract Sceletium tortuosum (Zembrin) in healthy adults — randomised controlled safety/tolerability trialView study →Reference 14Murbach TS et al. · 2014AnimalA toxicological safety assessment of a standardized extract of Sceletium tortuosum (Zembrin®) in rats — 14-day and 90-day subchronic oral toxicity studyView study →}. These results are for kanna.

References

1. Smith MT, Field CR, Crouch NR, Hirst M. (1998). The distribution of mesembrine alkaloids in selected taxa of the Mesembryanthemaceae and their modification in the Sceletium-derived ‘Kougoed’ — chemical survey. Pharmaceutical Biology, 36(3):173–179. https://doi.org/10.1076/phbi.36.3.173.6350
2. Krstenansky JL. (2017). Mesembrine alkaloids: review of their occurrence, chemistry, and pharmacology — review. Journal of Ethnopharmacology, 195:10–19. https://pubmed.ncbi.nlm.nih.gov/27939420/
3. Harvey AL, Young LC, Viljoen AM, Gericke NP. (2011). Pharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids — in vitro receptor/enzyme panel. Journal of Ethnopharmacology, 137(3):1124–1129. https://pubmed.ncbi.nlm.nih.gov/21798331/
4. Reay J, Wetherell MA, Morton E, Lillis J, Badmaev V. (2020). Sceletium tortuosum (Zembrin®) ameliorates experimentally induced anxiety in healthy volunteers — randomised, double-blind, placebo-controlled trial. Human Psychopharmacology, 35(6):1–7. https://pubmed.ncbi.nlm.nih.gov/32761980/
5. Terburg D, Syal S, Rosenberger LA, et al. (2013). Acute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala — randomised controlled fMRI trial. Neuropsychopharmacology, 38(13):2708–2716. https://pubmed.ncbi.nlm.nih.gov/23903032/
6. Gericke J, Harvey BH, Pretorius L, et al. (2024). Sceletium tortuosum-derived mesembrine significantly contributes to the anxiolytic effect of Zembrin®, but its anti-depressant effect may require synergy of multiple constituents — in vivo zebrafish. Journal of Ethnopharmacology, 319(Pt 1):117113. https://pubmed.ncbi.nlm.nih.gov/37660956/
7. Maphanga VB, Skalicka-Woźniak K, Budzynska B, et al. (2022). Mesembryanthemum tortuosum L. alkaloids modify anxiety-like behaviour in a zebrafish model — in vivo zebrafish. Journal of Ethnopharmacology, 290:115068. https://pubmed.ncbi.nlm.nih.gov/35134486/
8. Loria MJ, Ali Z, Abe N, Sufka KJ, Khan IA. (2014). Effects of Sceletium tortuosum in rats — animal behavioural model. Journal of Ethnopharmacology, 155(1):731–735. https://pubmed.ncbi.nlm.nih.gov/24930358/
9. Gericke J, Steyn SF, Viljoen FP, et al. (2025). Neuro-inflammatory and behavioral changes are selectively reversed by Sceletium tortuosum (Zembrin®) and mesembrine in male rats subjected to unpredictable chronic mild stress — animal model. Cells, 14(13). https://pubmed.ncbi.nlm.nih.gov/40643548/
10. Chiu S, Gericke N, Farina-Woodbury M, et al. (2014). Proof-of-concept randomized controlled study of cognition effects of the proprietary extract Sceletium tortuosum (Zembrin) targeting phosphodiesterase-4 in cognitively healthy subjects — randomised, double-blind, placebo-controlled crossover trial (NCT01805518). Evidence-Based Complementary and Alternative Medicine, 2014:682014. https://pubmed.ncbi.nlm.nih.gov/25389443/
11. Dimpfel W, Franklin R, Gericke N, Schombert L (2018). Effect of Zembrin® and four of its alkaloid constituents on electric excitability of the rat hippocampus — ex vivo/in vitro. Journal of Ethnopharmacology, 223:135–141. https://pubmed.ncbi.nlm.nih.gov/29758341/
12. Coetzee DD, López V, Smith C. (2016). High-mesembrine Sceletium extract (Trimesemine™) is a monoamine releasing agent, rather than only a selective serotonin reuptake inhibitor — in vitro cell model. Journal of Ethnopharmacology, 177:111–116. https://pubmed.ncbi.nlm.nih.gov/26615766/
13. Nell H, Siebert M, Chellan P, Gericke N. (2013). A randomized, double-blind, parallel-group, placebo-controlled trial of extract Sceletium tortuosum (Zembrin) in healthy adults — randomised controlled safety/tolerability trial. Journal of Alternative and Complementary Medicine, 19(11):898–904. https://pubmed.ncbi.nlm.nih.gov/23441963/
14. Murbach TS, Hirka G, Szakonyiné IP, Gericke N, Endres JR. (2014). A toxicological safety assessment of a standardized extract of Sceletium tortuosum (Zembrin®) in rats — 14-day and 90-day subchronic oral toxicity study. Food and Chemical Toxicology, 74:190–199. https://pubmed.ncbi.nlm.nih.gov/25301237/
15. Smith MT, Crouch NR, Gericke N, Hirst M. (1996). Psychoactive constituents of the genus Sceletium N.E.Br. and other Mesembryanthemaceae: a review — historical/ethnobotanical review. Journal of Ethnopharmacology, 50(3):119–130. https://pubmed.ncbi.nlm.nih.gov/8691846/
16. Plants of the World Online (2026). Delosperma cooperi (Hook.f.) L.Bolus — native range and habitat — species database. Royal Botanic Gardens, Kew. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:361479-1
17. South African National Biodiversity Institute. Delosperma nubigenum — description, distribution and habitat — species database. PlantZAfrica. https://pza.sanbi.org/delosperma-nubigenum
18. North Carolina Extension Gardener Plant Toolbox. Delosperma — genus description, native range and cultivation — species database. NC State Extension. https://plants.ces.ncsu.edu/plants/delosperma/
19. North Carolina Extension Gardener Plant Toolbox. Delosperma cooperi — description, size and origin — species database. NC State Extension. https://plants.ces.ncsu.edu/plants/delosperma-cooperi/

View all 19 references▾