The Diverse World of Ice Plants: A Comprehensive Guide to Their Benefits, Cultivation, and Ecological Impact

The generic name “ice plant” forms the image of shiny, dewdrop-kissed leaves, the appearance that gives the extraordinary succulants their descriptive name. The members in the main from the family Aizoaceae are recognized from the occurrence of their epidermal bladder cells, likened to tiny ice droplets shimmering in the sun. Apart from their beauty value, ice plants offer the array of qualities, from high gastronomic and medical potentiality to inestimable ornamentation. Of course, the generic name hides the critical classification as well: while some ice plant species exemplify vast prospects in health and sustainable agriculture, others exemplify serious ecological perils through their fairly invasive tendency. The understanding of the contrast is critical in responsible culture and renewable environmental management so that their prospects could be realized while the perils could be mitigated. The paper explores the plural world of ice plants in order that the many genera involved under this generic appellation be explicated, their extraordinary characters, qualities, culture requirements be determined, and the critical ecological issues surrounding their culture be discussed.

Key Genera of “Ice Plants”: Disambiguating a Common Name

The common term “ice plant” is often confusing as it encompasses some rather diverse genera with quite dissimilar characteristics and effects. For clarification and prudent decision-making, the following major types, often referred to as “ice plants”, ought to be distinguished from one another:

Mesembryanthemum crystallinum (Common/Crystalline Ice Plant): This annual or perennial succulent is arguably the species at the forefront of health and sustainability research. Native to coastal North Africa, Sinai, and Southern Europe, it is known for its edible leaves and rich profile of bioactive compounds. Despite its benefits, M. crystallinum* can also exhibit invasive tendencies in specific regions, including parts of Southern California, Australia, and various areas of North and South America, warranting careful management.

Delosperma (Cold Hardy Ice Plant): Originating from the high-elevation mountains and deserts of South Africa and Lesotho, Delosperma species are celebrated ornamental groundcovers. They are highly prized for their vibrant, daisy-like blooms that blanket landscapes in an array of colors and their remarkable ability to withstand colder temperatures than many other succulents. Crucially, Delosperma* species are generally not considered invasive outside their native habitats.

Carpobrotus edulis (Highway Ice Plant / Hottentot Fig Ice Plant): This species represents the most notorious and aggressively invasive form of “ice plant.” Widely propagated in the past for erosion control, particularly along coastal California, Carpobrotus edulis* has become an ecological menace, forming dense monocultures that outcompete native flora, disrupt ecosystems, and destabilize soil. Its severe environmental impact necessitates its careful identification and management.

By recognizing these fundamental distinctions, we can navigate the world of ice plants with a more informed and responsible approach, appreciating their diversity and addressing their challenges appropriately.

Mesembryanthemum crystallinum (Common Ice Plant): Benefits and Uses

Mesembryanthemum crystallinum, often referred to as the Common or Crystalline Ice Plant, is a halophytic marvel gaining significant attention across various fields, from nutrition and health to environmental remediation and sustainable agriculture. Its unique ability to thrive in saline environments and its rich biochemical profile make it a plant of considerable promise.

Nutritional and Health Benefits

The Common Ice Plant is a powerhouse of bioactive compounds, offering a wide array of potential health benefits that are increasingly supported by scientific research:

Antioxidant Activity: Extracts from M. crystallinum* exhibit potent antioxidant activity, as measured by various assays including DPPH (2,2-diphenyl-1-picrylhydrazyl), ORAC (Oxygen Radical Absorbance Capacity), TEAC (Trolox Equivalent Antioxidant Capacity), FRAP (Ferric Reducing Antioxidant Power), and ferrous ion chelating activity. This robust antioxidant capacity is primarily attributed to its high polyphenol content, which helps combat oxidative stress, a key contributor to chronic diseases and aging.

Antihypertensive Properties: Research indicates that M. crystallinum* extracts possess significant Angiotensin I-converting enzyme (ACE)-inhibitory activity, achieving up to 90.5% inhibition at a concentration of 1 mg/mL. ACE is a crucial enzyme in the renin-angiotensin system, which regulates blood pressure. By inhibiting ACE, the plant can help relax blood vessels and lower blood pressure, making it a potential natural aid for managing hypertension. Flavonoids such as diosmin, apigenin, and luteolin, alongside various phenolic acids, are believed to be the primary compounds responsible for this beneficial effect.

Hypoglycaemic Effect: The extract demonstrates considerable Dipeptidyl Peptidase IV (DPP-IV)-inhibitory activity, reaching 73.1% inhibition at 1 mg/mL. DPP-IV is an enzyme that degrades incretin hormones, which play a vital role in regulating blood glucose levels by stimulating insulin release and suppressing glucagon. By inhibiting DPP-IV, M. crystallinum* can help maintain stable blood sugar levels, presenting a promising avenue for the management of type II diabetes. Apigenin, p-coumaric acid, and luteolin are key contributors to this hypoglycaemic action.

Nootropic Activity: Intriguingly, M. crystallinum also exhibits Prolyl Oligopeptidase (PEP)-inhibitory activity, showing an impressive 98.6% inhibition at 1 mg/mL. PEP is an enzyme implicated in the degradation of neuropeptides, which are crucial for cognitive functions. Its inhibition can potentially enhance memory and learning, making M. crystallinum* relevant for research into cognitive health and neurodegenerative diseases such such as Alzheimer’s and Parkinson’s. Luteolin and diosmin are suggested to be the primary inhibitors responsible for these nootropic effects.

Key Bioactive Compounds: The plant’s rich pharmacological profile is due to a diverse array of bioactive compounds. Flavones, particularly apigenin (at approximately 38%), diosmin (17.7%), and luteolin (11.9%), constitute the major polyphenolic group. Other important compounds include 4-hydroxybenzoic acid, p-coumaric acid, and various hydroxycinnamic acid derivatives. Furthermore, M. crystallinum* contains D-pinitol, a cyclitol that has shown promise in improving hyperglycemia and memory impairment in diabetic animal models.

Mineral Content: As a halophyte, M. crystallinum* possesses a remarkable capacity to store essential minerals. It can accumulate significant concentrations of Ca2+, Mg2+, and particularly high levels of Zn2+. This mineral richness can contribute significantly to human dietary intake, especially in regions where these minerals might be deficient in staple crops.

Culinary Use

Beyond its health benefits, Mesembryanthemum crystallinum is appreciated for its unique culinary attributes. Traditionally consumed in various cultures, it has found its way into haute cuisine due to its succulent texture and distinctive flavor profile. Its leaves offer a slightly salty, sweet, and sometimes subtly lemony taste, often described as reminiscent of the sea. It can be enjoyed raw in fresh salads, adding a crisp, juicy texture and a unique burst of flavor, or lightly stir-fried, where its succulence is preserved.

Ecological and Agronomic Potential

The inherent characteristics of M. crystallinum make it a plant of significant ecological and agronomic interest, particularly in the face of global environmental challenges:

• Halophyte: Its most defining ecological trait is its halophytic nature, meaning it naturally thrives in saline environments. This resilience to high salinity levels is a valuable trait, especially as salinization of agricultural lands becomes an increasing global concern, offering a potential crop for otherwise unproductive soils.

Phytoremediation:M. crystallinum* exhibits a remarkable ability to reduce soil salinity and mitigate metal contamination, including heavy metals like Cadmium (Cd) and Nickel (Ni). This phytoremediation capability makes it a valuable candidate for decontaminating polluted sites, restoring degraded lands, and adapting to the challenges posed by soil salinization in arid and semi-arid regions.

• Drought Resistance: The plant is exceptionally well-adapted to drought conditions, a critical feature in an era of increasing water scarcity. Its drought tolerance is partly attributed to its ability to switch its photosynthetic pathway from C3 to Crassulacean Acid Metabolism (CAM) under stress conditions, enabling it to efficiently conserve water.

Other Applications

The versatility of M. crystallinum extends to other practical applications:

• Cosmetics: Leaf extracts are increasingly utilized in the cosmetic industry for their skin hydration and anti-aging properties, leveraging their rich antioxidant and mineral content.
• Traditional Medicine: Historically, various parts of the plant have been used in traditional medicine for treating infections, reducing inflammation, and managing conditions like diabetes, reflecting an empirical understanding of its beneficial compounds.
• Soap Substitute: Crushed leaves of the ice plant can even serve as a natural soap substitute due to their saponin content, highlighting their practical utility in diverse contexts.

Cultivation of Mesembryanthemum crystallinum

Cultivating Mesembryanthemum crystallinum is relatively straightforward, thanks to its hardy and adaptable nature. Understanding its environmental preferences and unique physiological mechanisms is key to successful growth, whether for culinary, medicinal, or ecological purposes.

Environmental Requirements

Sun Exposure:M. crystallinum* is a heliophile, meaning it strongly prefers and requires full sun exposure. It cannot thrive in shaded conditions, needing at least 6-8 hours of direct sunlight daily to grow vigorously and develop its characteristic bladder cells and crystalline appearance.

• Soil: This plant is not particular about rich soil and, in fact, thrives in sandy, loamy, well-drained, and even nutritionally poor or saline soils. The primary requirement is excellent drainage to prevent root rot, as waterlogged conditions are detrimental to its growth. Its tolerance for saline soil makes it suitable for coastal gardens or areas with high soil salinity.

Temperature: The ideal temperature range for M. crystallinum* is between 12 to 30 °C (54 to 86 °F). While it can tolerate some fluctuations, it is generally sensitive to frost and can be killed by freezing temperatures. In regions with cold winters, it is typically grown as an annual or protected during the colder months.

Watering:M. crystallinum* is highly adapted to drought conditions and prefers dry to moist soil. Once established, it requires infrequent watering, thriving on low amounts of water. Overwatering is a common mistake that can lead to root rot; allowing the soil to dry out completely between waterings is advisable.

Growth and Metabolism

A remarkable aspect of M. crystallinum‘s physiology is its metabolic flexibility:

• C3 to CAM Switch: Under stress conditions such as high salinity, drought, or high temperature, the plant can switch its photosynthetic pathway from C3 to Crassulacean Acid Metabolism (CAM). This adaptive mechanism allows it to open its stomata at night to accumulate CO2, minimizing water loss during the hot, dry daytime hours. This metabolic switch significantly increases its water use efficiency and enables it to survive in harsh environments.
• Bladder Cells: The prominent epidermal bladder cells, which give the plant its “ice plant” appearance, play a crucial role in its adaptation. These specialized cells develop to store water and, importantly, sequester NaCl (sodium chloride) for osmotic adjustments. By concentrating salt in these external cells, the plant protects its internal tissues from salinity stress and maintains cellular turgor.

Propagation

Mesembryanthemum crystallinum primarily propagates from seeds. The seeds are generally viable and can germinate readily under suitable conditions. However, some studies suggest that seed dormancy can be broken or germination rates improved by specific treatments, such as dry heat treatment, which mimics natural conditions in its native arid environments.

Optimizing Growth

To enhance the yield and quality of M. crystallinum, several factors can be optimized:

• Light Quality: Research indicates that specific light wavelengths can influence the plant’s phytochemical composition and biomass. Blue LEDs, for example, can promote the synthesis of beneficial phytochemicals, while red LEDs may enhance overall biomass production. Tailoring light spectra in controlled environments can maximize desired plant characteristics.
• Plant Growth-Promoting Rhizobacteria (PGPR): Introducing beneficial soil microorganisms, known as Plant Growth-Promoting Rhizobacteria, can significantly enhance the plant’s growth, nutrient uptake, and stress tolerance, leading to improved yield and quality.

Delosperma (Cold Hardy Ice Plant): Ornamental Value and Care

Delosperma species, often simply called “hardy ice plants,” are a popular choice among gardeners seeking vibrant, low-maintenance groundcovers. Their exceptional hardiness, coupled with an explosion of color, makes them ideal for a variety of landscape applications.

Description

Delosperma varieties are succulent groundcovers characterized by their fleshy, often cylindrical or triangular leaves, which can vary in color from bright green to grayish-green. Their most striking feature, however, is their profusion of brightly colored, daisy-like flowers. These blooms come in an astonishing array of hues, including vivid pink, fiery red, brilliant orange, deep purple, soft lavender, cheerful yellow, and pure white. The flowers typically open fully in direct sunlight, creating a dazzling carpet of color, and then close at night or on cloudy days.

Hardiness

One of the defining advantages of Delosperma is its remarkable cold hardiness. Most varieties are reliably hardy in USDA Zones 5-9, with some exceptionally robust cultivars capable of thriving even in Zone 4. This extended hardiness range, compared to many other succulents, allows them to be grown as perennials in colder climates. In some cases, exposure to winter cold is actually beneficial, stimulating a more profuse and vibrant flowering display in the spring.

Cultivation

Successful cultivation of Delosperma hinges on replicating the well-drained, sun-drenched conditions of their native mountain and desert habitats.

Exposure: Full sun is absolutely essential for Delosperma* to flower profusely. They require at least 6-8 hours of direct sunlight daily. In insufficient light, they may become leggy, produce fewer blooms, and their flowers may not open fully.

Soil: The most critical factor for Delosperma* is lean, well-drained soil. Sandy, gravelly, or rocky soil compositions are ideal, mimicking their natural environment. Poorly draining soils, especially heavy clay, are a death sentence for these succulents, leading quickly to root rot and plant demise. Incorporating grit, perlite, or sand can significantly improve drainage in heavier soils.

Watering:Delosperma* are highly drought-tolerant once established. While they appreciate deep watering once every 7-10 days during dry spells without rain, they should be watered sparingly. Overwatering is the primary cause of failure. In winter, reduce watering significantly, especially in colder climates, as dormant plants require very little moisture.

• Fertilizer: These plants are not heavy feeders and generally require little to no supplemental fertilizer. In spring, a light application of compost or a slow-release granular fertilizer can be beneficial, particularly for plants grown in containers or those in very poor soils, to support robust flowering.
• Pruning: Minimal pruning is usually required. In early spring, before new growth begins, remove any dead, damaged, or unsightly foliage. Light shearing of spent flowers and older growth in late summer or early fall can encourage a bushier habit and a potential second flush of blooms, though this is not strictly necessary.

Propagation:Delosperma* is remarkably easy to propagate. Stem cuttings taken in spring or summer root readily in well-drained soil. They can also be divided in spring, and many varieties will self-seed, contributing to their spread in the garden.

Pests and Diseases

When grown in proper conditions (full sun, well-drained soil, infrequent watering), Delosperma are generally resistant to most pests and diseases. However, certain issues can arise:

• Pests: Occasional problems may include aphids, mealybugs, whiteflies, or vine weevils, particularly in stressed plants or those in less-than-ideal environments. These can usually be managed with horticultural soaps or targeted treatments.
• Diseases: The most common and lethal disease is root rot, almost always a result of overwatering or poorly draining soil. Ensuring proper cultural conditions is the best preventive measure. Fungal diseases can also occur in consistently damp conditions.

Landscape Uses

The versatility and beauty of Delosperma make it an excellent choice for numerous landscape applications:

• Rock Gardens: Its low-growing habit and preference for rocky conditions make it a natural fit for rock gardens.
• Perennial Borders: It adds a splash of vibrant, long-lasting color to the front of perennial borders.
• Curbside Strips and Hell Strips: Its drought tolerance and ability to withstand tough conditions make it ideal for challenging urban planting areas.

Containers:Delosperma* thrives in pots and containers, allowing for flexible placement and easier winter protection in very cold climates.

• Xeriscapes: As a drought-tolerant succulent, it is a staple in water-wise xeriscape designs.

Groundcover on Slopes: Its spreading habit makes it effective for covering slopes and helping to prevent soil erosion, though it’s important to differentiate its effectiveness from the problematic Carpobrotus edulis*.

The Issue of Invasiveness and Responsible Gardening

While the “ice plant” moniker embraces species with significant benefits and ornamental appeal, it is critical to address the severe ecological threat posed by certain members of this group. The distinction between benign and invasive species is paramount for responsible gardening and environmental stewardship.

Mesembryanthemum crystallinum, despite its valuable properties, is listed as invasive in several regions, including parts of Southern California, Australia, and other areas of North and South America. Its ability to thrive in disturbed, saline, and drought-prone environments, coupled with prolific seed production, allows it to outcompete native vegetation, particularly in coastal and arid ecosystems.

However, the most egregious example of an invasive “ice plant” is undoubtedly Carpobrotus edulis, commonly known as Highway Ice Plant or Hottentot Fig. Introduced globally for erosion control and ornamental purposes, particularly along coastal California, its aggressive spread has created an ecological crisis. Carpobrotus edulis forms incredibly dense, suffocating monocultures that carpet vast areas, effectively choking out native flora. It achieves this by blocking sunlight from reaching the soil, preventing native seeds from germinating, and physically smothering existing plants.

Furthermore, its impact extends beyond simple competition. As Carpobrotus edulis decomposes, it releases accumulated salts and other compounds into the soil, subtly altering soil chemistry and creating an inhospitable environment for native species, which are not adapted to such conditions. This “salting” of the soil can further inhibit the germination and growth of other plants, creating a self-perpetuating cycle of invasion.

The claim that Carpobrotus edulis is effective for erosion control has also been largely disproven. While its dense mats appear to hold soil, its roots are relatively shallow and superficial. Unlike deep-rooted native vegetation, these shallow roots are ineffective at stabilizing soil on steep slopes, particularly during heavy rains or seismic activity. In fact, the weight of the dense, water-laden mats can even contribute to landslides and erosion, rather than preventing it.

The ecological consequences of this invasiveness are profound and far-reaching:

Reduced Biodiversity: By displacing native host plants, Carpobrotus edulis* directly reduces the food sources and habitats available for native insects and pollinators. This, in turn, disrupts the entire food chain, negatively impacting birds, reptiles, and mammals that rely on these native insects and seeds.

• Habitat Alteration: The dense mats alter microclimates, change soil chemistry, and physically exclude native species, fundamentally transforming natural habitats into impoverished monocultures.

Increased Fire Risk: While succulent, the dense, matted growth of Carpobrotus edulis* can dry out in summer, creating a highly flammable fuel source in coastal areas, particularly once the underlayer begins to decompose.

Responsible gardening practices are therefore paramount. This includes carefully identifying the species before planting, opting for non-invasive alternatives like many Delosperma varieties for ornamental purposes, and participating in removal efforts for invasive species where appropriate. Awareness and education are key to mitigating the environmental damage caused by these aggressive invaders.

Conclusion

The diverse group of plants collectively known as “ice plants” presents a fascinating paradox: a spectrum of organisms ranging from highly beneficial to environmentally destructive. Mesembryanthemum crystallinum, the Common Ice Plant, stands out for its exciting opportunities in health, nutrition, and sustainable agriculture. Its rich profile of bioactive compounds, coupled with its halophytic and drought-resistant nature, positions it as a promising candidate for cultivation in challenging environments and for addressing global food security and health challenges. Simultaneously, Delosperma varieties offer robust and colorful groundcovers, enriching gardens with their vibrant blooms and resilience, particularly in colder climates.

However, the pervasive issue of invasiveness, particularly concerning Mesembryanthemum crystallinum in some regions and the highly destructive Carpobrotus edulis, underscores a critical lesson in ecological stewardship. The seemingly benign act of planting can have profound and lasting impacts on native ecosystems, reducing biodiversity, altering soil composition, and even contributing to erosion.

Therefore, a nuanced understanding of specific species and their ecological implications is not merely academic but a practical necessity for responsible cultivation and environmental management. By choosing the right “ice plant” for the right purpose and place, we can harness the valuable properties of these unique succulents while safeguarding our planet’s precious biodiversity.

Ready to explore more fascinating plants and cultivate a thriving garden responsibly?

Visit Sprout sanctum for expert tips, in-depth guides, and inspiration for your green sanctuary!