The cactus family contains far more variety than the familiar image of a single spiny column in a desert. Some species remain smaller than a coin, some store much of their body underground, and others open enormous flowers for only a short period at night.
1. Blossfeldia liliputana: the miniature specialist
Native to parts of the Andes, Blossfeldia liliputana is widely recognized as the smallest cactus species. Mature plants can remain around a centimeter across and often grow in rock cracks. Their tiny, flattened bodies expose little surface area to drying air, while protected crevices provide a more stable microclimate than open ground.
2. Turbinicarpus subterraneus: much of the plant is hidden
This small Mexican cactus places a substantial storage root below the soil while leaving a comparatively small stem exposed. The arrangement protects water-storing tissue from direct sun and temperature extremes. Its limited range also makes habitat protection and responsible cultivation important.
3. Selenicereus undatus: a cactus that produces dragon fruit
Formerly placed in the genus Hylocereus, this climbing cactus produces dragon fruit. Its large flowers open at night, when nocturnal pollinators are active and temperatures are lower. The plant’s climbing stems allow it to use trees or supports to reach brighter positions rather than investing energy in a self-supporting trunk.
4. Obregonia denegrii: the artichoke cactus
The only species in its genus, Obregonia denegrii forms a low rosette of triangular tubercles that resembles an artichoke. Its body sits close to the ground and can blend into limestone terrain. Because wild populations are limited, buyers should avoid illegally collected specimens and choose documented nursery-propagated plants.
5. Crested saguaro: a rare growth form
Most saguaros grow from a single rounded tip, but a small number develop a fan-shaped crest. The U.S. National Park Service reports that scientists do not yet agree on a single cause; proposed explanations include genetic mutation and physical damage. A crested saguaro is not a separate species, but a rare form of Carnegiea gigantea.
What most cacti have in common
Cacti share a collection of water-saving traits. Their spines are modified leaves, while their stems perform photosynthesis. Broad, shallow roots can collect rain quickly. Many species use CAM photosynthesis, opening stomata mainly at night to reduce water loss. Ribbed stems can expand after rain and shrink during dry periods.
These adaptations do not make cacti indestructible. Excess water, illegal collecting, habitat loss, freezing temperatures, and unsuitable soil can kill species that are highly specialized for a narrow environment.
Sources: Kew Plants of the World Online, U.S. National Park Service: cacti and desert succulents, U.S. National Park Service: crested saguaro, Kew profile of Carnegiea gigantea
