Synonyms:

Dinteranthus wilmotianus subsp. impunctatus
Mesembryanthemum inexpectatum

Habitat:

Originating from Warmbad, Namibia, Dinteranthus inexpectatus is uniquely adapted to thrive in specific environmental conditions. This fascinating succulent can be found nestled amidst quartz hills, often taking shelter beneath quartz stones. It has evolved to flourish in an ecosystem characterized by occasional rainfall, typically occurring in the autumn months. This specialized habitat has played a crucial role in shaping the distinctive features and behavior of this remarkable plant.

Description:

Dinteranthus inexpectatus, often referred to as the “surprising living rock,” boasts a spherical form with typically just one pair of leaves, occasionally forming small clusters. These leaves take on a smooth, egg-like shape, standing at a height of 2.5 to 4.5 centimeters and reaching up to 5 centimeters in width. Their hue is a uniform milky-white or grey, occasionally tinged with a delicate pink. Notably, they lack any discernible dots and are broadest at their midpoint, extending taller than their widest span. Interestingly, these semi-ovate leaves unite for more than half of their length, occasionally displaying a slight gap and closing tightly to form a sphere during dry spells.
Upon close inspection, one may observe one or two subtle ridges along the back of the leaves, particularly towards the apex. These ridges feature dome-shaped cells in the epidermis, often crowned with small knobs, culminating in a denser cuticular knob at the center. When the plant blooms, it produces a solitary flower measuring 1.5 to 4.5 centimeters in diameter, exhibiting a rich, deep yellow hue. The flower encompasses eight sepals, while the petals boast a striking golden-yellow tone, sometimes adorned with a reddish undertone. Within, you’ll find six to eight stigmas.
Turning attention to its fruits, the valve wings are only moderately wider than the expanding keels, and in the open capsule, they do not touch at their base. This results in (7-)8 locules within. Notably, this species is easily distinguishable from its close relative, Dinteranthus wilmotianus.

Cultivation:

Dinteranthus inexpectatus, known for its distinctive appearance and vibrant blooms, requires specific care and attention. Providing it with the right conditions will result in a rewarding display of colors and shapes, especially during autumn. While it may be a bit finicky about its environment, with proper maintenance, even experienced growers can keep it thriving.
This small succulent can be cultivated on a patio table, sunny windowsill, or in a greenhouse. It has a slow growth rate compared to other mesembs. For its soil, it prefers a well-draining mix with minimal compost and a high proportion of grit, coarse sand, or small lava gravel. It can be grown outdoors in sunny, dry rock crevices, but protection against winter wetness is crucial. Alternatively, it can thrive in alpine houses with poor, well-drained soil.
When it comes to repotting, keeping it in a small pot, either as a solitary clump or in a shallow terracotta seed pan, works best. Dinteranthus inexpectatus may stay in the same pot for many years, though it tends to have better flowers when given its own small individual pot.
In terms of light, it benefits from as much as you can provide, but be cautious about exposing it to direct sunlight in the peak of summer. Without proper protection, it can get scorched.
For watering, it needs some moisture throughout the year, with slightly more in spring and autumn. During the coldest winter months, keep it on the drier side and resume regular watering after the old leaves have completely dried. Overwatering and poor ventilation can lead to problems, so it’s essential to allow the soil to dry out between waterings. If in doubt, it’s better to hold off on watering.
During its resting period in winter, a light top spray once a week can mimic the desert dew and prevent excessive dehydration, especially in homes with central heating. After flowering through the winter season, the plant doesn’t require watering, as it draws on stored water and nutrients from the outer succulent leaves.
Feeding it with a cactus and succulent-specific fertilizer during the growing season is beneficial, but avoid excessive fertilization to prevent excess vegetation that’s susceptible to fungal diseases. Some growers fertilize frequently, while others do so sparingly. For highly succulent mesembs like Dinteranthus inexpectatus, fertilization is not always necessary.
In terms of hardiness, it’s best to overwinter it above 5°C, though it can tolerate light frost down to -7°C for short periods if the soil is dry. It thrives in USDA zones 9A to 11.
Dinteranthus inexpectatus can be grown in containers or rock gardens, adding beauty to any space. While generally pest-free in good condition, it may attract insects like red spiders, mealy bugs, and sciara flies. Regular misting can deter red spiders, while mulching with grit can discourage sciara flies. Scales, thrips, and aphids are rarely problematic. Treating your Dinteranthus inexpectatus with a systemic insecticide twice a year in spring and autumn can help prevent infestations.
Rot is a minor concern for Dinteranthus inexpectatus, provided it is watered and aired correctly. Fungicides may not be particularly effective if proper care is neglected.

Propagation:

Dinteranthus inexpectatus can be propagated either from its tiny seeds or by dividing mature clumps. To start from seed, plant them in pots filled with fine, well-draining sand during the warm months of spring and summer. Gently cover the seeds with a thin layer of grit and water from below, using a fungicide to prevent damping off. For the initial 3-4 days, cover the pots with glass or clear perspex to maintain high humidity levels. Afterward, switch to light shadecloth and mist the pots once or twice a day for the next two weeks. By then, most seeds should have sprouted. As the young plants grow, you can gradually reduce the frequency of misting, from every second day to every third day.
For propagation through division, take cuttings from a mature Dinteranthus inexpectatus plant. Each cutting should include one or more rosettes along with a portion of the root system. Allow the cuttings to air dry for a couple of days. Once dried, position the cuttings on the soil surface and gently insert the stem ends partially into the soil. It’s advisable to keep the cutting somewhat upright to encourage downward root growth. It’s worth noting that rooting Dinteranthus inexpectatus from cuttings can be challenging and often less successful compared to propagation from seed, as they readily grow from seeds.

Curiosity:

The peculiar appearance of Dinteranthus plants has garnered them considerable popularity among succulent enthusiasts. They share a growth pattern akin to Lithops, but unlike Lithops, they primarily grow above the ground. (Except for Dintheranthus vanzily, which has a partially subterranean habit similar to Lithops, with the tips of its leaves exposed above the soil.) Due to their uncanny resemblance to the surrounding rocks, they are often referred to as mimicry plants, blending seamlessly into their natural habitat and becoming inconspicuous when not in bloom. Displaying a distinct pebbly texture, they are commonly known as pebble plants or living stones. Each species of Dinteranthus is intricately linked to a specific type of rock formation and is found exclusively in that particular environment. This natural camouflage serves as a defense mechanism against herbivores, reducing the need for chemical protection.

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