Synonyms:

Uebelmannia pectinifera var. multicostata
Uebelmannia pectinifera var. pseudopectinifera

Habitat:

Uebelmannia pectinifera, a plant species, is limited to a single location situated in the northeastern part of the Diamantina mountains in Brazil. Its total area of existence is around 3,000 square kilometers. The plant species is typically found in areas that are 650 to 1350 meters above sea level. It usually grows in campo rupestre, which is a type of dry savanna, and in rocky areas where it can thrive in small flat spaces of organic leaf litter mixed with sand that are found in the crevices or pockets of crystalline rocks. Unfortunately, Uebelmannia pectinifera is facing a significant risk of population decline due to multiple threats, particularly overcollection. The population is severely fragmented, leading to its classification as an endangered species. Interestingly, this species is more commonly found in collections than in its natural habitat.

Description:

Uebelmannia pectinifera is a unique species of cactus that can grow up to 100 cm tall, although it typically measures between 10 and 50 cm. This species is known for its multiform characteristics and is highly variable in different habitats. It comprises a complex of numerous local forms that are linked to others by populations of plants with intermediate characteristics. Three subspecies are recognized, including the nominate form (subsp. pectinifera), subsp. flavispina (Buining & Brederoo) P.J.Braun & Esteves, and subsp. horrida (P.J. Braun) P.J. Braun & Esteves. It is important to note that the circumscription into subspecies may not fully represent the complexity of the species in nature.

The stem of Uebelmannia pectinifera is solitary or rarely aggregated, and can have a globular, fusiform, elongated or cylindrical shape. The plant is known to grow up to 1 m tall and 10-15(-17) cm wide, and has gummiferous ducts under the epidermis. The epidermis is dark reddish-green to reddish-brown or green to grey-green, and can have or lack waxy plates. The texture is rough, and the color of the plant can vary depending on sun exposure.

The plant has 13-40 (15 to 18 in subsp. pectinifera) acute, straight, vertical, and prominent ribs that are not tuberculate. These ribs can reach up to 5 mm high and 5-7 mm broad. Areoles are 2 mm in diameter, set closely to form an almost continuous felt-like line down the ribs’ sides. They have sparse greyish or brownish wool when young, which later becomes glabrescent.

Central spines of Uebelmannia pectinifera are dark brown/grey to black, but can also be whitish or yellowish brown. There are 1 to 4 spines, up to 1.5(-2) cm long, that are close set, often interlacing, neatly arranged, and give a comb-like effect. They’re porrect or spreading, and straight. The plant lacks radial spines.

The flowers of Uebelmannia pectinifera are diurnal and have a slender funnel-shaped greenish-yellow appearance. They are 8-16 mm long and 6-10(-12) mm in diameter. The tube is around 8 mm, with triangular bract-scales, white hairs, and bristles. Perianth-segments are pale yellow, tinged reddish or greenish, while the style is 6-7 mm and stigma-lobes 7-8. The flowers come sporadically from early spring to late summer.

The fruit of Uebelmannia pectinifera is pear-shaped to cylindrical and is violet-red to bright pinkish. It measures 1.5-2.5 cm long and 6-8 mm wide, with few glabrescent or slightly woolly bract-scales. The seeds are keeled, brown, shiny, smooth, and measure 1.7-2.4 x 1.3-1.6 mm, with flat testa cells.

Cultivation:

Growing Uebelmannia pectinifera can be challenging. Unlike other cacti, this species is tropical and requires a certain level of humidity in the air. To maintain the necessary humidity, it’s important to regularly steam them during the summer. However, they are also susceptible to root rot, so care should be taken not to overwater them. As a result, they are often grafted onto hardier species. Here are some tips for cultivating Uebelmannia pectinifera:

Place them in a very bright location that is sheltered from direct sunlight, especially during the hottest parts of the day in the summer.
Ensure that the temperature remains above 10ºC, as they cannot tolerate cold temperatures.
Water every 3-4 days in the spring and summer, decreasing the frequency in the autumn and suspending watering completely in the winter. During the spring and summer, add frequent misting to the irrigation water to maintain a sufficiently humid microclimate.
Use well-draining substrate that is slightly calcareous, rich in minerals, and enriched with a little humus.
Fertilize once a year at the beginning of the growing season.
Choose large and deep pots to contain the strong and deep roots, and repot once every two years. 

Propagation:

Uebelmannia pectinifera exclusively reproduces through seeds, but growing them can be challenging. As a result, it’s common to graft the plants to make them easier to cultivate, particularly during winter. Ideally, the rootstock should be more durable than Uebelmannia to increase the chances of success.

Curiosity:

The species was named after Friedrich Uebelmann, a Swiss cactus collector who discovered the plant in 1955 in the state of Bahia, Brazil.
The specific epithet “pectinifera” comes from the Latin word “pectin” (meaning “comb”) and “ferre” (meaning “to bear”), and refers to the comb-like spines that cover the cactus.
Uebelmannia pectinifera is highly valued by collectors for its attractive appearance, which includes the comb-like spines and bright yellow flowers that bloom in the spring. It is also used as an ornamental plant in gardens and greenhouses.
The species is commonly known as “Uebelmannia”, “Comb Cactus”, or “Golden Ball Cactus”.

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