Cacti of the Southwest

Cacti of the Southwest

Cacti of the Southwest Overview

A cactus is a member of the plant family Cactaceae, which consists of approximately 127 genera with some 1750 known species of the order Caryophyllales.

Learn about the Cactus Wren.

Related Content

Places to view the cacti of the southwest and safety tips:

• How to Remove Cactus Spines
• Guide to Saguaro National Park
• Guide to Organ Pipe Cactus National Monument

Taxonomy

• Kingdom: Plantae
• Clade: Tracheophytes
• Clade: Angiosperms
• Clade: Eudicots
• Order: Caryophyllales
• Family: Cactaceae

Subfamilies and Genus of Cactacae

Subfamilies

• Cactoideae
• Maihuenioideae
• Opuntioideae
• Pereskioideae

Genus

• Carnegiea (Saguaro Cactus)
• Cylindropuntia (Cholla Cactus)
• Echinocactus  (Barrel Cactus) – One of my personal favorites! They have bright red to orange flowers and long white thorns. 
• Escobaria (Pincushion Cactus or Foxtail Cactus) – These cacti grow to approximately 6″ tall, are spherical-shaped, grow in a round cluster with 1/2″ since long dark spines with petite pink flowers with yellow centers that bloom in the spring to the early summer.
• Ferocactus (Barrel Cactus)
• Grusonia  (Club Cholla)
• Mammillaria (Globe Cactus, Nipple Cactus, Birthday Day Cake Cactus, Fishhook Cactus, or Pincushion Cactus)
• Opuntia (Prickly Pear or Pear Cactus) – This cactus needs full sun with well-drained soil. While it doesn’t grow tall, it does grow wide, up to 3′. It has “thorns” that are 1″ long and flowers that bloom from spring to summer that are pink to yellow.
• Pediocactus  (Hedgehog Cactus or Pincushion Cactus) – Round in appearance with spines on the base, this cactus blooms in the spring and showcases it flowers on the top. They normally grow to 6″ – 12″ tall and about 12″ wide.

Size and Body Description

Cacti occur throughout the world in a wide range of shapes, sizes, and environments (with most living in dryer areas and subject to drought conditions).

Leaves vs Spines vs Thorns

The great majority of cacti have no visible leaves; photosynthesis takes place in the stems (which may be flattened and leaflike in some species). Exceptions occur in three (taxonomically, four) groups of cacti. All the species of Leuenbergeria, Pereskia, and Rhodocactus are superficially like normal trees or shrubs and have numerous leaves with a midrib and a flattened blade (lamina) on either side.

Many cacti in the opuntia group (subfamily Opuntioideae) also have visible leaves, which may be long-lasting (as in Pereskiopsis species) or produced only during the growing season and then lost (as in many species of Opuntia).

Even those cacti without visible photosynthetic leaves do usually have very small leaves, less than 0.5 mm (0.02 in) long in about half of the species studied and almost always less than 1.5 mm (0.06 in) long. The function of such leaves cannot be photosynthesis; a role in the production of plant hormones, such as auxin, and in defining axillary buds has been suggested.

Botanically, “spines” are distinguished from “thorns”: spines are modified leaves, and thorns are modified branches. Cacti produce spines, always from areoles, which are an identifying feature of cacti. Spines are present even in those cacti with leaves, such as Pereskia, Pereskiopsis, and Maihuenia, so they clearly evolved before complete leaflessness. Some cacti only have spines when young, possibly only when seedlings. This is particularly true of tree-living cacti, such as Rhipsalis and Schlumbergera, but also of some ground-living cacti, such as Ariocarpus.

In addition to normal-length spines, members of the subfamily Opuntioideae have relatively short spines, called glochids, that are barbed along their length and easily shed. These enter the skin and are difficult to remove due to being very fine and easily broken, causing long-lasting irritation.

The above information about leaves vs spines vs thorns is directly from Wikipedia.

Range

Below is a table showing each species of cactus, where they are found (we are tracking Arizona, California, Nevada, New Mexico, and Utah), and links to articles for each one for you to learn more. At the bottom of the page is a visual guide to show you which articles we have written for each of the cacti.

Beavertail Cactus in Sand Dune in Valley of Fire

Cacti of the Southwest

What is a Barrel Cactus (Echinocactus grusonii)

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What is Beavertail Cactus

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What is Buckhorn Cholla

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What is a Strawberry Hedgehog

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References Used

• Wikipedia – Cactus (multiple articles)
• National Park Service – Cacti
• iNaturalist – Cacti of Nevada

Cacti of the Southwest