Designing with Cactus

What is a Cactus?

Many people, even those who consider themselves familiar with arid plants, get confused when it comes to what really constitutes a cactus. Isn’t it basically anything spikey that grows in dry climates? No! A cactus is, in fact, a very specific thing.

Cacti are members of the family Cactaceae. There are approximately 1,800 species of cactus.

Two specific things set cacti apart from other plants:

  • Not all cacti have spines when they mature, but a great way of distinguishing a spiney cactus from other spikey plants in the field is the presence of “areoles,” little bumps on the plant from which clusters of spines grow. If the spines on the plant are not growing in clusters out of these bumps it’s not a cactus!

Cactus aerole

  • All cacti also have a specific flower structure. Though the flower of each cactus species may be very different, all cactus flowers have many tepals (a term used when the sepals of a flower are indistinguishable from the petals) that are somewhat fused; hundreds of stamens; and many-lobed stigmas.

Yellow prickly pear cactus flower

Designing with Cacti

As a group, cacti are drought tolerant and are a great option for any water-conscious landscape. But xeric gardens aren’t the only ones that can benefit from the use of cactus! Their frequently strong sculptural or geometric forms and punchy colors can add punctuation to any landscape design, as long as the growing conditions are right.

Cacti with upright or twisting forms are popular for use against a striking backdrop such as a richly-colored wall, or for their silhouette against a vista. They can also be grouped together for great large-scale textural effects, or consider pairing their chunky forms with something soft such as Mexican Feather Grass (Nassella tenuissima) for inviting contrast. Barrel cacti are perfect for creating rhythm and reinforcing patterns in design, and the bold textures and colors of pad cacti (Opuntia) provide great backdrops or focal points in the landscape.

Agaves, other succulents, and grasses are great design companions, but cacti can really be added to any composition with complimentary leaf colors, contrasting textures, and similar environmental requirements.

Most cacti are very sensitive to over-watering, so make sure the soil is very well drained, and the other plants in your design have compatible water use requirements. Use The Plantium to easily find great cacti and appropriate design companions for your next project!

Fun Facts about Cacti

  • All cacti are succulent, but not all succulents are cacti!
  • All cacti are native to the Americas, though they have spread around the world post-colonization.
  • Although they are typically slow growers, cacti are very successful in arid climates, so much so that in certain countries like Australia many cacti are considered noxious weeds.
  • Cacti grow in a wide variety of places, though mostly in habitats that experience some drought. People associate cacti with hot climates, but there are many species that are hardy to -30 deg. F and lower!
  • Cacti come in a wild variety of shapes, sizes, and forms, from the stereotypical Saguaro, barrel, and prickly pear, to the Rose Cactus (Pereskia grandifolia) which looks like a tree or shrub at first glance.
  • Most cacti don’t have true leaves, instead performing photosynthesis in their modified stems. However some cacti, like the rose cactus, can be very leafy!

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