Synonyms:

Echinopsis lageniformis f. monstruosa

Habitat:

Trichocereus bridgesii f. monstruosa is a cultivar of horticultural origin. The type species, Trichocereus bridgesii, naturally grows on the arid highlands of Bolivia, in very bright and dry environments with marked temperature fluctuations, where it roots in poor, rocky, and well-drained soils.

Description:

The name of this plant combines the genus Trichocereus, from the Greek thrix (“hair”) and cereus (“candle”), referring to the bristly spines and columnar growth habit typical of the species, with the specific epithet bridgesii, named in honor of the British botanist and naturalist Thomas Bridges, who collected numerous South American specimens during the 19th century. The designation f. monstruosa comes from the Latin monstruosus and describes the plant’s abnormal and irregular growth, characterized by deformed stems.

Trichocereus bridgesii f. monstruosa belongs to the genus Trichocereus and to the family Cactaceae. It is a columnar cactus with a clumping growth habit and a tendency to branch at the base. It typically reaches 25-40 cm (10-16 in) in height, occasionally growing up to 60 cm (24 in). The stem is light green with a glaucous tint and is composed of multiple upright sections that are smooth and slightly tapered toward the apex. The upper portion of the stem is cylindrical, smooth, and spineless, while the basal area may show faint ribbing and sparse honey- to light-brown spines up to 4-7 cm (1.6-2.8 in) long, which tend to decrease as the plant matures.

As a sterile cultivar, the plant does not produce flowers or fruit. The mutation responsible for its monstrous growth compromises its normal reproductive capacity, preventing both flowering and seed production.

Cultivation:

This is a relatively easy plant to grow, characterized by slow growth.

It prefers a highly well-draining soil, as this cultivar is particularly sensitive to waterlogging. The ideal substrate is light and mineral-based, consisting of a mix of cactus potting soil, coarse sand, and inert materials such as pumice or lava rock, with only a minimal organic component.

During the growing season, in spring and summer, watering can be carried out approximately every 10 days, always ensuring that the soil has dried out completely and avoiding any water stagnation. In fall and winter, watering should be drastically reduced or suspended, especially if the plant is kept in a cool environment, to prevent rot and allow proper dormancy.

It prefers a bright exposure with intense, diffused light. It also tolerates a few hours of direct sunlight, particularly in the morning or late afternoon, while light shading is recommended during the hottest summer hours to prevent stem scorch. When kept dry, it can tolerate temperatures down to -12 °C (10 °F).

Fertilization should be carried out only during the growing season, in spring and summer. A cactus-specific fertilizer, low in nitrogen and rich in potassium, is recommended, applied at reduced strength every 4-6 weeks. Fertilization should be discontinued in fall and winter.

Repot every 2-3 years, preferably in spring, once the root system has completely filled the container. Use a pot slightly larger than the previous one and fresh, well-draining soil.

This species is not considered toxic to humans. The only precautions concern the presence of spines on the basal portion of the stem, which may cause minor irritation or small injuries if handled without protection. Wearing gloves is therefore recommended during routine care and repotting.

It is generally regarded as a robust and resilient plant, but it may occasionally be affected by issues common to cacti. The main risks involve root or stem rot, usually caused by excess moisture or poor drainage. Common pests include mealybugs and spider mites, particularly in indoor or poorly ventilated conditions.

Care tip: to assess the plant’s overall health, regularly observe the stems: the appearance of dark spots may indicate excess moisture or improper watering, while a pale or whitish coloration usually signals insufficient light.

Propagation:

Propagation occurs exclusively through vegetative means, via stem cuttings, as this is a sterile form that does not produce seeds. Cuttings should be taken from healthy offsets and left to callus for several days in a dry, shaded environment before planting. Once placed in a light, well-draining substrate, they root slowly.

Curiosity:

Within the monstrous form, two main clones can be distinguished: clone A, which is more heavily branched and spiny, and clone B, characterized by fewer branches and reduced spination. The latter is commonly known as the “penis cactus” due to the distinctive shape of the stem apex, which makes it easily recognizable.