Ibervillea
Ibervillea is a small genus of caudiciform plants in the gourd family (Cucurbitaceae), native to the arid and semi-arid regions of the Americas — centred on Mexico and ranging from the southwestern United States south into Central America. These are true caudex plants: each forms a swollen, above-ground water-storing stem (a caudex) from which slender, seasonal climbing vines emerge to scramble over surrounding shrubs, only to die back again when the dry season returns. Their bizarre, bottle- or boulder-like bodies make them prized among growers of "fat plants" and other succulent oddities.
Description
Members of Ibervillea are defined by their caudex — a fleshy, tuberous stem that swells with stored water and, in most species, sits partly or wholly above the soil surface. In older plants this body can become large, gnarled and characterful, ranging in shape from a smooth green sphere to a rough, corky, grey-brown boulder depending on the species and how it is grown.
Each growing season the caudex sends up one or more thin, wiry vines bearing lobed, gourd-family leaves and coiling tendrils that let the plant clamber over neighbouring vegetation. The flowers are small, star-shaped and yellowish to greenish, and are generally dioecious — that is, male and female flowers are borne on separate plants, so more than one individual is usually needed to set fruit. Pollinated female plants produce small, rounded berries that ripen bright red. When the dry season arrives the vines wither away completely, and the plant rests as a bare caudex until conditions improve.
Distribution
The genus is centred on Mexico, with its range extending north into Texas, Arizona and adjacent parts of the southwestern United States and south through Central America to Guatemala and Belize. Plants grow in dry scrub, thornforest and rocky desert margins, typically rooting among rocks or at the base of shrubs that give the seasonal vines something to climb and offer the caudex a little shade.
Notable species
- Ibervillea sonorae — perhaps the best-known species in cultivation, forming a large, rounded to irregular grey-brown caudex; sometimes sold under the evocative Mexican name "wereke" or "guareque."
- Ibervillea lindheimeri — a hardier species from Texas and northern Mexico, often called the Lindheimer's globeberry or balsam gourd, with a partly buried tuber and bright red fruit.
- Ibervillea tenuisecta — a finely divided-leaved species of the desert Southwest, sometimes known as the slimlobe globeberry.
Cultivation
Ibervillea are grown much like other caudiciform succulents and reward a grower willing to respect their strong seasonal rhythm. Plant them in a very free-draining, mostly mineral mix and give bright light — good light keeps the vines compact and encourages a fat, well-shaped caudex rather than a stretched, weak one.
The single most important thing is to follow the plant's cycle. Water regularly while the vine is actively growing, always letting the mix dry out between waterings, then taper off and keep the plant dry once the foliage begins to die back for its dormant rest. Watering a leafless, dormant caudex is the quickest route to rot. Keep plants warm and frost-free; while the Texan Ibervillea lindheimeri tolerates more cold than most, none should be exposed to hard freezes. Many growers plant the caudex low at first and gradually expose more of it at each repotting to develop that prized above-ground body. See Watering for general technique.
Propagation
Seed is the usual and most reliable way to raise Ibervillea, and because most species are dioecious you will generally need both a male and a female plant to obtain viable seed. Sow onto a warm, gritty surface and keep lightly moist until germination; seedlings begin to swell their little caudices surprisingly early, which is part of their charm. Cuttings are not a practical route for these plants, so seed-grown stock is the norm in the hobby.
Hobby notes
Ibervillea occupy a niche among collectors of caudiciform and "living rock" curiosities rather than the mainstream cactus trade, so they are more often found at specialist nurseries and succulent shows than in general garden centres. They are grown almost entirely as species; named cultivars are essentially unknown, with individual plants valued instead for the character of an old, well-grown caudex. Their gourd-family foliage means they can attract the same sap-sucking pests as other soft-leaved plants — see Pests and diseases — but a healthy, well-lit specimen on a proper wet-and-dry cycle is generally trouble-free and long-lived.
See also
- Caudex — the swollen water-storing stem that defines these plants
- Ibervillea sonorae · Ibervillea lindheimeri · Ibervillea tenuisecta
- Soil and potting mix · Watering · Repotting · Propagation — seed · Pests and diseases