Haworthia truncata - Cactus Club

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Haworthia truncata

Plant of the Month > Species G to H

by Bruce Brethauer

     Haworthia truncata is one of the most unusual species of a genus which is characterized by its gems. Most species of Haworhia produce smallish rosettes of succulent leaves, each of which is typically marked with patterned windows, textured leaf surfaces, often featuring white beaded and ridged outgrowths on the dermis. Most species are highly caespitose, eventually producing dense clusters with dozens (and sometimes hundreds) of individual rosettes. Unlike virtually all other Haworthias, Haworthia truncata does not produce a rosette, but instead produces its leaves in two ranks, in a distichous arrangement, producing odd fans of tightly appressed leaves. The leaf tips end abruptly with a flat window. Plants in habitat frequently grow with their leaves buried in the soil, with only the leaf tips exposed. The windowed leaves admit light deep into the leaf tissues - enabling them to photosynthesize even when they are nearly buried in the soil. This is usually an adaptation to extreme drought and exposure - other plants with similar attributes (Fenestraria, and Lithops for example) frequently grow exposed to full sun and/or wind; by burying the greater portion of the plant below ground, they reduce their exposed surface area, limiting moisture loss. Growing in such exposed sites is atypical for most Haworthia species, which typically grow under the protection and shade of taller plants, but indications are that Haworthia truncata plants are indeed found in more exposed situations.

     Haworthia truncata  is native to the winter rainfall region of the Little Karoo in the Western Cape. It is known from the Oudsthoorn, De Rust and Calitzdorp areas. The species is fairy variable in its traits: some plants are highly caespitose, producing multiple offsets practically from the outset, eventually producing plants with dozens of offsets (similar to the plant in the accompanying photograph) while other individuals may remain solitary for years; some populations produce comparatively thin leaves (as in variety tenuis), while other varieties produce thicker leaves (as in variety crassa), and the windowed leaves of some populations are virtually unadorned, while in other plants, these are patterned with curious streaks and splotches. Some growers have selectively bred plants which exhibit exceptional patterning on their leaf tips, and a few growers occasionally offer variegated plants for sale. The leaves are very tough, and feel as though the plant was sculpted from hard plastic or candle wax. Like many other Haworthia species with similarly hard leaf surfaces, this is a very slow growing plant - some plants only add a few additional leaves each year. The flowers of this species are small and are not terribly showy, with greenish white petals, and green midribs. Flowers are borne on long wiry spikes, which bear a number of small (about 1/4 inch) flowers. Plants will typically produce an intermittent succession of additional spikes from fall through rarly winter, with an occasional spike being produced at other times of the year.

   Compared to other Haworthias, Haworthia truncata is somewhat more of a challenge to grow. While it does well enough when provided with the basic guidelines for growing succulents, a few minor considerations and modifications may be called for. In habitat, this species tends to be a late summer and fall grower, producing its flowers at this time of the year. In my experience however, I have found this species  it to be a fairly opportunistic grower, with two growth spurts each year, one in spring, and the other in late summer, with a short resting period in summer, and a longer resting period in winter. It is probably best to water a bit less frequently in mid summer, and to water more frequently in spring, and from late summer through fall. I have also discovered that it is best to keep this plant fairly dry during the winter months, watering only enough to prevent root loss, but not enough to keep the soil wet for more than a few days, as cool and wet conditions can result in root loss from rot, and can lead to the eventual demise of the entire plant. It is a good idea to provide an extra gritty soil for this plant so that it does not remain wet for more than a few days at a time. Some growers incorporate coarse builders sand into their soil mix to provide additional drainage, but I prefer to use Turface All Sport or a similar product to provide additional drainage and airspace in the soil, but I have also used crushed stone, such as fine chick grit, or decomposed granite with good results. I also recommend a top dressing of pea gravel to help keep the crown of the plant dry. Even though plants in habitat may lie buried to their leaf tips, I have found that in cultivation this practice will frequently result in the death of the plant from rot. Unless you are a very experienced grower, I would advise that this plant should only be potted up to its crown - no deeper! While most of the Haworthias are tolerant of shade, Haworthia truncata will tolerate brighter light, and may even require very bright light for best growth. Properly acclimatized, by gradually increasing the plant's exposure to sunlight, it is even possible to grow this plant outside in full sun from spring through early fall summer. Whenever growing this plant indoors, always choose the brightest situation available.

    Because of their comparatively slow rate of growth, many plants will only need to be repotted every 2 to 4 years, with the more offsetting types requiring more frequent repotting, - approximately every 2 years

     Additional plants can be propagated from the rooted offsets produced on the ceaspitose varieties. These offsets are best detached whenever repotting the plant, but may also be carefully removed from the the potted plant as well (keep both plants dry for a week or two to allow the cut ends to heal, and to prevent infection from soil borne pathogens). It may also be possible to propagate additional plants from a single leaf. I have never attempted this technique with this species, and cannot relate how good the results are, but the technique involves cutting a leaf from the plant, and setting it aside in a warm, shaded area for a period of about 2 weeks to heal and callus; following that, it can be planted (callus side down) into a barely moist potting soil. In time, roots will become established, and a plantlet will eventually be produced. This technique will take considerably longer to produce an established plant than potting up an offset, but it offers the possibility of growing additional plants of especially desirable clones which are otherwise very slow to offset. Plants may also be grown from seed. While an occasional fruit and viable seeds may be "spontaneously"  produced, on flowering plants (plants appear to be self-fertile), the best way to insure fruit and seed production is to grow at least 2 different clones of this plant, and to cross pollinate them using a very fine photographers "spotting brush" to transfer pollen between the two plants. If pollination is successful, plants will produce small (about 1/2 to 3/4 inch long), sausage shaped fruits. The seed is ripe when the fruits dry and begin to split. The small, flat, brown seeds should be planted immediately, surface sewing it on a good seedling mix, and barely covering the seed with coarse sand, finely crushed granite (such as chick grit) or Turface All Sport. The seed may benefit from a period of cold stratification, where the seed pots are initially kept cool  (down to temperatures in the low 50's to upper 40's) and barely moist for a month or two, and then growing the seedling pots at warmer temperatures. In my experience, Haworthia seedlings germinate very sporadically, and growth is typically very slow, but this technique offers the possibility of growing a multitude of plants for those persons who are patient enough to grow these seedlings on to maturity.

      A final consideration; the closely appressed leaves provide an ideal place for insect pests to hide: mealy bugs, scale insects, and spider mites can easily occupy these spaces without being easily noticed. While Haworthias are not particularly prone to insect infestations I would nevertheless suggest that growers inspect the leaves of their plants carefully for any evidence of stow-away insects; whenever any pests are detected, isolate the plant, and treat it with an appropriate insecticide as soon as possible.

     Haworthia truncata is not only one of the great oddities of the plant kingdom, it is a remarkably attractive species, looking more like an piece of modern art than a living plant. Like many other members of the genus, this is a compact, slow growing species which makes few demands on the grower. While it is somewhat more of a challenge than some other species of Haworthia, it is really not a difficult plant to grow. Not every grower will have the patience to grow this species, given its slow rate of growth, but for those who have the patience, this is an exceptional plant, well worth the effort.

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