Weingartia
Weingartia is a genus of small, globular cacti native to the high valleys of Bolivia and northern Argentina, prized by collectors for their neat, tuberculate bodies and generous clusters of yellow to orange flowers borne near the crown. Long treated as a genus in its own right, Weingartia is now frequently united by botanists with Sulcorebutia and Rebutia, and its species have shuffled between all three names in the literature — a tangle that means growers often encounter the same plant under several labels.
Description
Plants in this genus are typically solitary or slowly clustering, forming firm, flattened-globular to shortly cylindrical bodies rarely more than a handful of centimetres across. The ribs are broken up into distinct, spirally arranged tubercles, each tipped by a woolly areole bearing short, often comb-like or bristly spines that range from pale straw to dark brown. Many species sit low against a stout, sometimes carrot-like taproot that helps them survive drought and cold in habitat.
The flowers are the genus's chief attraction: funnel-shaped and typically yellow, gold or orange (occasionally with red or violet tones in some forms), they open near the top of the plant and are frequently produced in a ring, so that a mature specimen can crown itself with a dozen or more blooms at once in spring and early summer. The small, dry fruits split to release fine seed.
Distribution
Weingartia is a genus of the Andean highlands, concentrated in the inter-Andean valleys of central and southern Bolivia and extending into the far north of Argentina. Plants grow at considerable altitude on rocky slopes, in gritty mineral soils and rock crevices, exposed to strong light, wide day-to-night temperature swings and a pronounced dry season. This montane origin is worth remembering in cultivation — many forms tolerate more cold than their small size suggests, provided they are kept dry.
Taxonomy
The boundaries of Weingartia are famously unsettled. Molecular studies have shown that Weingartia, Sulcorebutia and Rebutia are very closely related, and several authors now fold all of them into a single broadly defined Weingartia (or, following other treatments, into Rebutia). Because of this, a given plant may appear in collections and catalogues under two or three different genus names. For the hobbyist the practical point is simply that these are near relatives with broadly similar needs; the label on the pot may not be the last word.
Notable species
- Weingartia neocumingii — a widespread, free-flowering species with dense pale spination and masses of golden-yellow blooms; a good introduction to the genus.
- Weingartia fidaiana — a stout, taprooted highland plant valued for its neat body and yellow flowers.
- Weingartia lanata (often listed under Sulcorebutia) — woolly-areoled and richly flowered.
- Weingartia kargliana — a compact valley species representative of the many narrowly defined forms described from Bolivia.
Because of the shifting taxonomy, many plants sold as Sulcorebutia or Rebutia belong here as well; check synonyms when identifying a collection plant.
Cultivation
Weingartia species are among the more forgiving of the Andean globular cacti and make excellent windowsill or greenhouse subjects. Grow them in a very free-draining, mostly mineral mix, ideally in a pot deep enough to accommodate the taproot many species form. Give them bright light — full sun in temperate climates suits them and brings out good spination and flowering — and water thoroughly during the growing season once the soil has dried, easing off as autumn approaches. See Watering and Repotting for general technique.
A cool, completely dry winter rest is important. It ripens the plants for spring flowering and, coming from high-altitude habitats, most forms shrug off cold far better than they do damp; wet roots in winter are the usual cause of loss. Protect from prolonged hard freezes, but do not coddle them with warmth and moisture out of season.
Propagation
Seed is the most reliable and rewarding method, and since the genus flowers freely, seed is often available. Sow on a warm, gritty surface kept humid until germination; seedlings grow at a moderate pace. Species that offset can also be increased by removing and rooting the pups once they have their own roots — see Propagation — offsets, Propagation — seed and Propagation — cuttings for full walkthroughs. Choice or slow forms are sometimes grafted to speed them along, though most Weingartia grow well enough on their own roots that this is rarely necessary.
In cultivation
The genus is a favourite among collectors of small cacti precisely because so much variety is packed into little plants: differences in spine colour and density, body form and flower shade have produced a large number of named forms and field-collection numbers. The taxonomic overlap with Sulcorebutia and Rebutia means many growers treat the three as a single group on the bench, and hybrids between them occur. Named cultivars in the horticultural sense are uncommon; interest centres instead on the wealth of natural forms.
Common problems
- Rot — nearly always from overwatering or a slow-draining mix, especially over winter; the plant softens at the base or taproot.
- Etiolation — too little light produces a pale, elongated body and poor flowering.
- Pests — root mealybugs on the taproot and red spider mites on the body are the usual troubles; inspect at Repotting and see Pests and diseases.
See also
- Sulcorebutia · Rebutia — the closely allied (and often merged) genera
- Soil and potting mix · Watering · Repotting
- Propagation — seed · Propagation — offsets · Grafting