Lithops Indoor: Care Guide, Light, Water & Styling Tips

Introduction to Lithops Indoor: Why are these 'living stones' so unique for indoor cultivation?

Lithops are highly specialized succulent plants, renowned for their striking resemblance to small stones and pebbles, which serves as a clever survival mechanism against herbivores in their arid native environments. For indoor cultivators, their unique morphology, minimal size, and exceptionally low maintenance requirements—once their specific needs are understood—make them fascinating and rewarding subjects.

This detailed guide provides an in-depth understanding of Lithops spp., covering everything from their botanical classification and physical characteristics to precise care instructions for light, water, and soil. We will also address common problems, propagation techniques, and styling tips to ensure your 'living stones' thrive as captivating additions to your indoor plant collection.

• Living Stone Mimicry: Evolved to blend seamlessly with surrounding rocks, offering natural camouflage.
• Extreme Succulence: Fleshy leaves are designed to store water efficiently, ensuring survival during prolonged droughts.
• Distinct Fissure: A characteristic cleft between the two leaf bodies from which new leaves and delicate flowers emerge.
• Deep Taproot System: Crucial for anchoring the plant and accessing deep soil moisture in arid landscapes.
• Minimal Water Needs: Exceptionally drought-tolerant, with overwatering being the most common cause of demise.
• High Light Demand: Requires significant direct sunlight to maintain compact form, vibrant coloration, and overall health.

What is Lithops? Lithops, also known as 'living stones,' are a genus of highly specialized succulent plants within the Aizoaceae family, endemic to the extremely arid and semi-arid regions of Southern Africa.

These remarkable plants are famed for their extraordinary mimicry, closely resembling the stones and pebbles in their natural habitat, which helps them evade predation. The genus name Lithops itself is derived from the Ancient Greek words λίθος (lithos), meaning 'stone,' and ὄψ (ops), meaning 'face,' perfectly describing their appearance.

Comprising over 30 recognized species and numerous subspecies and varieties, Lithops demonstrate incredible diversity in patterns, colors, and leaf window structures. Each species has adapted to specific rock formations and soil types in its localized range, leading to their distinct phenotypic variations. They belong to the broader family Aizoaceae, often referred to as the "fig-marigold family" or "ice plant family," which includes many other unique succulent genera from Southern Africa.

Key Benefits & Uses of Lithops: What makes Lithops a desirable addition to an indoor plant collection?

Lithops offer a unique blend of aesthetic appeal, low maintenance, and fascinating biological adaptations, making them highly sought after by succulent enthusiasts and collectors. Their miniature size and peculiar appearance contribute significantly to their charm and utility in diverse indoor settings.

Beyond their decorative value, cultivating Lithops provides a rewarding challenge for those interested in understanding advanced succulent care and mimicking arid environments indoors. Here's why these 'living stones' are so beneficial and popular:

• Unique Aesthetic Value: Their stone-like appearance and diverse patterns make them unparalleled conversation starters and highly decorative elements.
• Minimal Space Requirement: Ideal for small apartments, windowsills, or office desks due to their compact size, typically 1-3 cm in diameter.
• Exceptional Drought Tolerance: Perfect for plant owners who travel frequently or prefer low-watering plants, thriving on infrequent irrigation.
• Fascinating Growth Cycle: Observing their seasonal growth, old leaves shriveling, and new leaves emerging from the fissure is a captivating process.
• Low Nutrient Needs: Require very little fertilization, simplifying their care routine.
• Pet-Friendly: Generally considered non-toxic to pets, though ingestion in large quantities should still be avoided. (Source: ASPCA plant list).
• Therapeutic Hobby: The precise and patient care required can be a meditative and relaxing activity for many gardeners.
• Educational Opportunity: Offers a practical lesson in xerophytic adaptations and plant evolution.
• Versatile Styling: Can be beautifully arranged in minimalistic pots, elaborate succulent arrangements, or terrariums (with caution regarding humidity).
• Collectors' Item: With over 30 species and many cultivars, Lithops provide a vast and engaging field for collectors.
• Air Purification (Minor): Like all plants, they contribute minimally to indoor air quality by absorbing CO2 and releasing oxygen.
• Longevity: With proper care, individual Lithops plants can live for 10-20 years or even longer, becoming long-term companions.
• Stress Reduction: The presence of greenery, even miniature plants, has been linked to reduced stress and improved well-being.

Indoor Care & Maintenance for Lithops: Providing optimal conditions for Lithops indoors hinges on understanding their specific environmental requirements for light, water, soil, and temperature, mimicking their arid native habitats.

Successful indoor cultivation of Lithops relies heavily on replicating the challenging conditions of their Southern African origins. This means paying meticulous attention to their seasonal growth cycle, especially concerning watering, and ensuring they receive ample light.

Understanding each of these factors is crucial to prevent common issues like rot from overwatering or etiolation from insufficient light. Let's break down the essential components of Lithops care indoors.

Light: How much light do Lithops need indoors?

Lithops require intense, direct sunlight for at least 4-6 hours daily to thrive, ideally from a south-facing window in the Northern Hemisphere. Insufficient light is a common cause of etiolation (stretching), loss of vibrant coloration, and failure to flower.

If natural light is inadequate, particularly during winter months or in less optimal window exposures, supplementary artificial grow lights are highly recommended. Full-spectrum LED grow lights, positioned 6-12 inches above the plants for 12-14 hours per day, can effectively replicate their natural light conditions. Rotate pots periodically to ensure even exposure.

Water: How much water do Lithops need, and how often should they be watered?

Watering Lithops is perhaps the most critical and often misunderstood aspect of their care, as they have a distinct seasonal watering schedule dictated by their growth cycle. Overwatering is the single biggest killer of Lithops.

General Rule: Water only when the plant shows visible signs of thirst, such as the tops of the leaves appearing slightly concave or wrinkled, and only at specific times of their growth cycle.

• Spring (Post-winter shedding): After the old leaves have completely shriveled and new leaves are fully formed and visible, begin light watering. This is typically from late spring to early summer. Water thoroughly, allowing the soil to dry out completely before watering again.
• Summer (Active Growth/Flowering): Continue watering when dry, but be mindful of extreme heat. If temperatures consistently exceed 30°C (86°F), Lithops may enter a summer dormancy, and watering should be reduced or stopped until temperatures cool. Most Lithops flower in late summer or autumn.
• Autumn (Pre-winter shedding): As temperatures cool and days shorten, Lithops may enter their next growth phase, absorbing water from the old leaves to form new ones. Reduce watering significantly, or stop entirely once you see the fissure begin to widen or new leaves pushing up.
• Winter (Dormancy/New Leaf Formation): Absolutely no water should be given during winter (typically November to March in the Northern Hemisphere) as the plant resorbs water from the old outer leaves to fuel the growth of the new inner leaves. Watering during this period will almost certainly cause rot.

When you do water, soak the soil thoroughly until water drains from the bottom. Then, ensure the pot drains completely and do not water again until the soil is bone dry and the plant shows signs of thirst. Use rainwater or distilled water if your tap water is very hard.

Humidity: What are the ideal humidity levels for Lithops?

Lithops thrive in low humidity environments, mirroring their arid desert origins. Standard indoor household humidity levels, especially those below 50%, are generally suitable. High humidity, especially when combined with cool temperatures and poor air circulation, can contribute to fungal growth and rot.

Misting is entirely unnecessary and can be detrimental, leading to fungal issues or leaf spots. Focus on providing excellent air circulation, which can be achieved by placing them near an open window (if temperatures allow) or with a gentle fan in enclosed spaces. Avoid placing them in naturally humid rooms like bathrooms or kitchens.

Temperature: What temperature range do Lithops prefer?

Lithops are quite tolerant of a wide range of temperatures but prefer consistent conditions. The ideal daytime temperature range is between 20-29°C (68-85°F), with nighttime temperatures ideally dropping a few degrees, similar to desert environments. They can tolerate higher temperatures, especially when dormant and kept dry.

During winter dormancy, they can withstand cooler temperatures, even down to 5-10°C (41-50°F), provided they are kept completely dry. Frost is lethal, so ensure they are protected from freezing conditions. Avoid sudden and extreme temperature fluctuations, which can stress the plant.

Soil: What is the best soil mix for Lithops?

The cardinal rule for Lithops soil is excellent drainage and aeration. A standard succulent or cactus mix is often not gritty enough and retains too much moisture. The ideal substrate mimics their natural rocky, fast-draining desert soils.

A highly porous, mineral-rich potting mix is essential. A good custom blend typically consists of:

• 50-70% Inorganic material: Pumice, perlite, lava rock, coarse sand (not play sand), akadama, or calcined clay. These components provide drainage and aeration.
• 30-50% Organic material: A high-quality succulent potting mix or coir. This provides minimal nutrients and some water retention without becoming waterlogged.

A popular and effective mix is 80% inorganic grit (e.g., pumice and lava rock) and 20% organic material. Ensure the particles are relatively coarse, avoiding fine dust. The pH preference is slightly acidic to neutral (6.0-7.0).

Fertilizer: Do Lithops need fertilizer, and if so, how often?

Lithops are extremely low feeders and generally do not require heavy fertilization. In their natural habitat, they grow in nutrient-poor soils. Over-fertilizing can lead to excessive, unnatural growth, causing the plant to burst or become mushy.

If you choose to fertilize, do so very sparingly and only during their active growth phase (spring/early summer). Use a highly diluted, low-nitrogen fertilizer (e.g., 5-10-10 or a specific succulent fertilizer) at about ¼ to ½ of the recommended strength. Fertilize no more than once a year, or even once every two years. Many growers find their Lithops thrive perfectly well without any supplemental feeding, relying on the minimal nutrients in their potting mix.

Potting: What is the best type of pot for Lithops?

Terra cotta pots are highly recommended for Lithops due to their porous nature, which allows for excellent airflow and evaporation of excess moisture from the soil. This helps prevent root rot. Ensure the pot has a large drainage hole at the bottom.

Because Lithops develop a substantial taproot, select a pot that is relatively deep compared to its width, typically 10-15 cm (4-6 inches) deep. While they are small plants, adequate depth is necessary to accommodate their root system. Grouping several Lithops in a wider, but still deep, pot can create a stunning arrangement, provided they are all on the same watering schedule.

Common Problems, Pests & Diseases of Lithops: Identifying and addressing issues promptly is crucial for the health and longevity of Lithops, as they are susceptible to specific problems primarily related to improper cultural care.

While Lithops are generally robust, their specialized needs mean that common indoor plant issues like overwatering or insufficient light can quickly lead to severe problems. Understanding the typical symptoms and their causes is the first step toward effective troubleshooting.

Most problems stem from environmental factors rather than aggressive pests. Here's a breakdown of the most frequent challenges encountered with Lithops.

Propagation & Repotting of Lithops: While slow-growing, Lithops can be propagated from seeds or by careful division, and require repotting periodically to refresh their soil and accommodate growth.

Propagating Lithops requires patience, especially from seed, but it is a rewarding way to expand your collection. Repotting is less frequent than with many other houseplants, primarily driven by the need for fresh, gritty soil.

Propagation:

Lithops are primarily propagated by seed, which is the most common and reliable method, or occasionally by division of naturally clumping plants.

1. Propagation from Seeds:

This is the most popular and often most rewarding way to propagate Lithops, allowing for the growth of many new plants.

1. Seed Collection: Lithops seeds are microscopic and harvested from dried seed pods after flowering and cross-pollination.
2. Timing: Sow seeds in late winter or early spring for best results.
3. Potting Medium: Use a finely sifted, sterile, very gritty succulent mix (e.g., 90% inorganic grit, 10% coir/fine peat).
4. Sowing: Scatter seeds thinly on the surface of the moist potting mix. Do not bury them, as they need light to germinate.
5. Germination Environment: Cover the pot with a clear plastic dome or cling film to create a humid environment. Place in bright, indirect light or under a grow light. Maintain a consistent temperature of 20-25°C (68-77°F).
6. Watering: Keep the soil consistently moist until germination, usually within 1-6 weeks. Use a fine mist spray to avoid disturbing tiny seedlings.
7. Hardening Off: Once seedlings appear, gradually introduce fresh air by incrementally opening the cover over several weeks. Once the cover is fully removed, reduce watering frequency, allowing the surface to dry slightly between waterings.
8. Growth: Lithops seedlings grow very slowly. Do not water during their first winter dormancy. Repot only after about 1-2 years when they are larger and more robust.

2. Division:

Some mature Lithops species can naturally produce multiple heads (pairs of leaves). These can sometimes be divided, but it's a delicate process with risks.

1. Timing: Perform division during transplanting, typically in spring when the plant is actively growing.
2. Selection: Only divide plants that have naturally formed multiple distinct heads, each with its own root system.
3. Procedure: Carefully unpot the plant. Gently tease apart the individual heads, ensuring each separated section has a robust taproot system. Use a sterile, sharp knife if necessary to separate root masses.
4. Healing: Allow the separated sections to callus for a few days in a dry, shaded place before repotting them into individual, well-draining pots.
5. Watering: Withhold water for at least a week after repotting to allow any root damage to heal.

Repotting:

Lithops do not require frequent repotting. They generally prefer to be root-bound and thrive in stable conditions. Repotting is typically done to refresh depleted soil or accommodate a significantly larger plant cluster.

1. When to Repot: Repot every 2-3 years, or when the plant outgrows its pot, the soil appears compacted, or the plant exhibits signs of nutrient deficiency despite proper feeding. The best time is in spring, after the old leaves have completely shriveled.
2. Preparation: Gather a clean terra cotta pot (slightly larger but deep enough for the taproot), fresh, gritty Lithops soil mix, and a trowel or small scoop.
3. Unpotting: Gently remove the Lithops from its old pot. Be extremely careful not to damage the delicate taproot. Brush away as much of the old soil as possible, inspecting the roots for any signs of rot or pests.
4. Trimming Roots (Optional): If the taproot is excessively long for the new pot or shows signs of circling, you can carefully trim the very end of it with a sterile blade. However, minimal disturbance is often best.
5. Potting: Add a layer of fresh potting mix to the new pot. Center the Lithops, ensuring the crown (where leaves meet roots) is at or slightly below the soil surface. Fill around the roots with the remaining mix, gently tapping the pot to settle the soil and remove air pockets. Do not bury the leaves, only the roots and stem base.
6. Post-Repotting Care: Do not water immediately after repotting. Wait for at least 7-10 days to allow any damaged roots to heal and reduce the risk of rot. Place in bright, indirect light during this period. After the waiting period, resume the regular watering schedule based on the plant's seasonal needs.

How to Grow Lithops at Home: A Step-by-Step Guide: Successfully cultivating Lithops indoors involves a seasonal approach to care, with particular attention to light and a strict 'no water in winter' rule.

Growing these 'living stones' at home can be immensely rewarding if you follow their natural growth cycles and adapt your care to their specific needs. Here's a practical, step-by-step guide to nurturing your Lithops:

1. Acquire Healthy Plants: Start with healthy Lithops from a reputable nursery. Look for firm, unwrinkled leaves, no signs of rot, and a well-drained pot. Many growers prefer young plants to adapt them to their home environment.
2. Choose the Right Pot: Select an unglazed terra cotta pot with a drainage hole. It should be at least 10-15 cm (4-6 inches) deep to accommodate the plant's substantial taproot, even for small specimens.
3. Prepare the Ideal Soil Mix: Create a well-draining, gritty soil mix. A mixture of 70-80% inorganic material (pumice, perlite, lava rock) and 20-30% organic material (cactus soil, coir) is highly recommended.
4. Proper Potting: Plant the Lithops so that the crown (the point where leaves meet roots) is about level with the soil surface. Ensure the leaves are not buried. Tamp the soil gently to secure the plant.
5. Provide Ample Light: Place your Lithops in the brightest available location. A south-facing window (Northern Hemisphere) offering 4-6 hours of direct sunlight is ideal. If natural light is insufficient, supplement with a full-spectrum LED grow light for 12-14 hours daily.
6. Master the Watering Cycle: This is the most crucial step.
• Winter (Approx. November-March): Absolutely NO WATER. The plant is absorbing old leaves to grow new ones.
• Spring (Approx. March-May): Once old leaves have fully shriveled and new leaves are visible and firm, begin light watering. Water thoroughly, then let the soil dry completely before the next watering.
• Summer (Approx. June-August): Continue watering when dry, but be cautious in extreme heat. Some Lithops may enter a slight summer dormancy and require less water.
• Autumn (Approx. September-October): Reduce watering significantly as the plant prepares for its next split and often flowers during this period. Stop entirely when you see signs of new leaves emerging or if the plant starts to absorb old leaves.
7. Ensure Excellent Air Circulation: Good airflow helps prevent fungal diseases. Avoid overly humid environments.
8. Fertilize Sparingly (if at all): Lithops rarely need fertilizer. If you do fertilize, use a very diluted (1/4 strength) low-nitrogen succulent fertilizer once a year during active growth in spring/early summer.
9. Monitor for Pests and Diseases: Regularly inspect your plants for signs of trouble. Prompt action against common issues like overwatering (root rot) and occasional pests (mealybugs) is key.
10. Repot Only When Necessary: Repot every 2-3 years to refresh the soil. Do this in spring, after the old leaves have shriveled and the new ones are established. Withhold water for a week after repotting.
11. Patience and Observation: Lithops are slow-growing and have specific rhythms. Learn to "read" your plants by observing their leaf texture and appearance to gauge their watering needs.

Interesting Facts & Cultural Significance of Lithops: Beyond their striking appearance, Lithops hold intriguing biological distinctions and have captured human fascination for centuries.

These 'living stones' are not just beautiful; they are marvels of evolutionary adaptation, inspiring wonder and sometimes even spiritual interpretations due to their unique mimicry and resilience.

• Master of Mimicry: Lithops are one of the most stunning examples of cryptic mimicry in the plant kingdom, evolving to blend perfectly with surrounding rocks. This is believed to deter herbivores, preventing them from being eaten in their harsh desert environment.
• Window Leaves: Many Lithops species have translucent "windows" on their apical (top) surface. These windows allow sunlight to penetrate deep into the plant body, reaching chlorophyll-containing tissues below the soil line, enabling efficient photosynthesis while the majority of the plant remains buried and protected from extreme heat and drought. This adaptation is called a "light tunnel" or "optical window."
• Native to 'Succulent Karoo': Most Lithops species are native to the Succulent Karoo biome of Southern Africa, a global biodiversity hotspot characterized by an extraordinary diversity of succulent plants found nowhere else on Earth (Source: World Wildlife Fund).
• Discovery by William John Burchell: The first *Lithops* specimen was discovered by the British botanist and explorer William John Burchell in 1811 in the Northern Cape of South Africa. He described finding a plant that "could scarcely be distinguished from the stones around it."
• Extreme Drought Adaptation: Their thick, paired leaves are essentially highly modified water storage organs. They can survive extended periods without rain by slowly consuming the water stored within their own leaves.
• Seasonal Growth Cycle: Lithops have a peculiar growth cycle where new leaves grow inside the old ones, drawing moisture from them until the old leaves are completely shriveled and act as a protective husk. This process ensures water conservation.
• Flowering Phenomenon: Despite their stone-like appearance, Lithops produce beautiful, daisy-like flowers, typically white or yellow, in late summer or autumn. These usually emerge from the fissure between the leaves and can be surprisingly large in proportion to the plant.
• Longevity: With proper care, individual Lithops plants can live for 10-20 years or even longer in cultivation, making them long-term botanical companions.
• Cultural Impact: Their uncanny resemblance to stones and their robust survival in extreme environments have led some cultures to view them as symbols of resilience, endurance, and quiet strength. In the gardening community, they are often seen as "living jewels" due to their unique beauty.
• Conservation Status: While many Lithops species are relatively common, some are localized endemics and face threats from habitat destruction, illegal collection, and climate change. Sustainable practices and purchasing from ethical sources are important for their conservation.

Conclusion & Key Takeaways for Lithops Indoor Care: Successful Lithops care boils down to understanding their desert adaptations and providing maximum light, minimal water (especially during dormancy), and exceptionally well-draining soil.

Cultivating 'living stones' indoors is a rewarding endeavor that connects you with one of nature's most extraordinary examples of plant evolution. By replicating their arid natural environment, you can enjoy these unique succulents for many years.

Remember that patience and keen observation are your best tools when caring for Lithops. Following their natural rhythms, particularly concerning the seasonal watering cycle, is far more critical than any complex fertilizer regimen. Embrace their minimalist beauty and marvel at their resilience.

• Light is Paramount: Full direct sun for 4-6 hours daily, supplement with grow lights if needed.
• Water Wisely, Not Often: Follow the seasonal watering guide precisely; overwatering is the biggest threat.
• Gritty Soil is Gold: Use a fast-draining, mineral-rich mix (70-80% inorganic material).
• Deep Pots for Taproots: Ensure pots are deep enough (10-15 cm) and have drainage holes.
• Observe and Learn: Pay attention to your plant's appearance for cues on watering and health.
• Patience is a Virtue: Lithops are slow growers with a unique lifecycle; appreciate their gradual changes.

Frequently Asked Questions (FAQs) About Lithops Indoor Care

1. What is the biggest mistake people make when caring for Lithops?

The single biggest mistake in Lithops care is overwatering, especially during their dormant periods when they are absorbing moisture from their old leaves to grow new ones. This rapidly leads to root rot and eventual plant death.

2. How often should I water my Lithops?

Watering Lithops depends almost entirely on their seasonal growth cycle, not a fixed calendar schedule. Generally, water sparingly in spring/early summer when old leaves have completely shriveled and new ones are firm. Stop watering entirely in winter (when old leaves are being absorbed) and reduce significantly in autumn.

3. What type of soil is best for Lithops?

The best soil for Lithops is a very gritty, fast-draining mix, typically composed of 70-80% inorganic materials like pumice, perlite, or lava rock, and 20-30% organic materials like a high-quality succulent potting mix or coco coir. Standard cactus soil is usually not gritty enough.

4. Do Lithops need direct sunlight?

Yes, Lithops absolutely need direct sunlight. They require at least 4-6 hours of direct sun daily to maintain their compact form, vibrant coloration, and to encourage flowering. A south-facing window or powerful grow lights are typically necessary indoors.

5. Why are my Lithops leaves turning soft and squishy?

Soft and squishy leaves are a classic symptom of overwatering and root rot. If this occurs, stop watering immediately, unpot the plant to inspect the roots, remove any rotted tissue, and repot in dry, fresh, gritty soil.

6. Why are my Lithops stretching or getting tall?

Stretching or elongation (etiolation) is a clear sign that your Lithops is not receiving enough light. Move it to a brighter location with more direct sunlight or increase the intensity and duration of supplemental grow lighting.

7. When do Lithops flower, and what do they look like?

Lithops typically flower in late summer or autumn (August to October in the Northern Hemisphere). Their flowers are daisy-like, usually white or yellow, and emerge from the fissure between the two leaves. They can be surprisingly large relative to the plant body.

8. Are Lithops toxic to pets?

Lithops are generally considered non-toxic to cats, dogs, and other household pets. However, it's always best to prevent pets from ingesting any houseplant, as even non-toxic plants can cause mild digestive upset if consumed in large quantities.

9. How long do Lithops live?

With proper care, individual Lithops plants can live for 10-20 years or even longer in cultivation, making them a long-term addition to your plant collection.

10. Can I grow multiple Lithops in one pot?

Yes, you can grow multiple Lithops in one pot, often creating visually appealing arrangements. The main consideration is ensuring all plants in the pot have similar watering needs and are on the same growth cycle to avoid over or underwatering specific individuals.

11. My Lithops are splitting, but the old leaves aren't disappearing. What should I do?

If new leaves are emerging but the old leaves remain plump, it's a sign of overwatering during the splitting period. Stop watering completely. The plant needs to absorb moisture from the old leaves to fuel new growth. Resume watering only when the old leaves have completely withered away.

12. What temperature range is best for Lithops indoors?

Lithops prefer daytime temperatures between 20-29°C (68-85°F) with slightly cooler nights. They can tolerate higher temperatures when kept dry. During winter dormancy, they can happily endure cooler temperatures down to 5-10°C (41-50°F), provided they are kept completely dry and protected from frost.

13. Do Lithops need high humidity?

No, Lithops thrive in low humidity environments, mirroring their arid desert origins. Average indoor humidity levels are usually fine, but avoid excessively humid conditions, misting, or placing them in high-humidity rooms like bathrooms, as this can encourage fungal issues.

14. Why is my Lithops shriveling and turning brown?

Shriveling can be a normal part of the Lithops growth cycle as new leaves absorb old ones, but it can also indicate severe underwatering. If coupled with browning and a dry, crispy texture, it could be sunburn. If mushy and brown, it's rot from overwatering. Examine other symptoms and your care routine to diagnose.

15. How do I propagate Lithops?

Lithops are primarily propagated from seeds, which should be sown on the surface of fine, gritty soil in spring and kept constantly moist until germination. Division is possible for multi-headed plants, but it is riskier and less common.