Cactus are great plants, for both pot and landscape cultivation. Sometimes we forget (at least I do) that they also can be great flowering plants. The following article is mostly a pictorial of some of the more impressive cactus flowers.
My primary interest in plants has rarely been in the flowers they make, which is one of the reasons I collect and grow ‘weird' plants (succulents and palms etc.)For most of the plants I grow, the flowers are fairly uninteresting or are non-existent.One of the groups of plants I find interesting, primarily because of their vegetative appearance, are the cacti.Many are beautiful, most are striking and some are just plant ugly or uninteresting.But whether they are one or the other, they at least also have something else going for them that sometimes is not on my radar when it comes to choosing and growing plants: they all flower.And some have spectacular flowers.The following article is a quick overview of some of the genera of cacti grown commonly in cultivation and their flowers. Most of the best photos in this section were not taken by me, so check the credits as you peruse.
In this article I will not try to cover all the cacti genera, as that would be a monumental undertaking for a short article.So I will limit this overview to the most common or spectacular species, or ones of which I personally am the most familiar.
Ariocarpus are peculiar cacti collected primarily for their rarity and interesting non-cacti-like looks.But these can have attractive flowers as well.
Astrophytums capricorne (photo by apachetrail) and A. myriostigma
Cereus is a large group of cacti, some quite popular in landscaping, but rarely, if ever, grown specifically for their flowers.This is primarily due to most of these blooming at night and also not being terribly colorful.But some have impressive flowers just the same.
Cereus aethiops Cereus hildmannianus Cereus sp.
Cereus forbesii and hankeanus
Cleistocacti are also rarely grown for their flowers as the flowers tend to pop up irregularly and almost make the plant look less elegant.But some have quite striking though small and simple looking flowers.
Cleistocactus strausii my favorite, Cleistocactus ferrareiCleistocactus samaipatanus
Cleistocacti micropetalus and C. winteri
These Cleistocactus (aka Borzicactus sp.) flower much of the year at the Huntington Botanical Gardens
Copiapoas are commonly grown cacti, many being collector's items due to their slow growth and/or rarity, but are certainly not known for their flowers.
Coryphanthasare smaller globoid species and some have attractive flowers.
Coryphantha elephantidensCoryphantha garessii (photo by CactusJordi) Coryphantha ramillosa (photo by CactusJordi)
Coryphantha longicornis (photo by CactusJordi) Coryphantha elephantidens for sale Coryphantha robustipina (photo by oldmudhous)
I have one species of Disocactus, or rat-tail cactus, and it is a spectacular flowerer.The other species are supposed to be excellent flowering cacti as well, but I have rarely seen them.
Disocactus flagelliformis (close up and plants in greenhouse) Disocactus phyllanthoides (photo by boojum)
Echinocacti tend to be large barrel species frequenting the landscaping projects of large public areas and are not usually associated with their flowers.However, they do have nice flowers that would be more impressive on less massive plants.
Echinocactus grusonii (Golden Barrel)- huge cactus... small flower); Echinocactus horizonthalonus
Echinocereus are a genus more likely grown for their brilliant flowers rather than their usually less-than-ornamental structures.Some of these are among the most prolific flowerers in my yard of cacti.
Echinopsis are the ultimate flowering cacti, with a large number of hybrids rarely grown for any other reason than their spectacular and enormous flowers (the hybrid plants themselves all look about the same).Sadly these flowers tend to be extremely ephemeral even for cactus flowers and some plants bloom 1 or 2 days out the entire year.Many other genera have been lumped into this genus (most notably Lobivia).
Epiphyllums are popular cacti though the non-hybrid species all have yellow or white flowers, which are nice, but not all that spectacular.But the hybrids, often referred to as Epicacti, are amazing and there are literally hundreds of varieties and colors available in cultivation. The flowers of these cacti are really only rivaled in the cactus world perhaps by the Echinopsis hybrids.The plants themselves are virtually identical and though not ugly are little to look upon the remainder of the year; most bloom around Mother's Day.
Some of the non-hybrids: Epiphyllum crenatum (photo Clare_CA); Epiphyllum oxypetalum (photo Happenstance); Epiphyllum hookeri (photo dave)
Epiphyllum grandilobum is one of the few colorful non-hybrid forms (photo johnfalconer)
Gymnocalycium is a very large genus of plants, many exceptionally ornamental even when not in flower thanks to their varied spines structure and suckering, globoid structures.Most have excellent flowers as well, and some bloom repeatedly nearly the entire warm part of the year.
Gymnocalycium horstii Gymnocalycium rotundulum Gymnocalycium sp. in my yard
Gymnocalycium pflanzii Gymnocalycium unknown species in my garden Gymnocalyicum bruchei
Mammillaria grahamii (one of the largest flowers of the Mammillarias) Mammillaria picta unknown Mammillaria in my yard
I have several Matucanas in the yard none which fail to produce several impressive flowers each year.
Matucana madisonorums Matucana aureiflora
Melocacti are popular potted plants (usually a bit tender for most climates to be landscape plants) and are prized for their fascinating cephalums and not for their flowers.But these can have nice flowers, too... they just tend to be pretty small relative to the overall plant.
Melocactus coccinea with pink flower
Opuntia is a massive genus often used primarily as a landscape plant and rarely thought of as a flowering ornamental, but many have very nice looking flowers.
Opuntia ficus-indica Opuntia verschaffeltii Opuntia violescens var. macrocentra
Pachycereus is one of the most impressive groups of cacti in terms of plant size and shape, but not one of the most impressive flowerers.
Pachycereus marginata dinky flower
Parodia is a very large and complex genus of cacti in which many other genera have been recently lumped into (e.g., Notocactus and many Echinocactus now belong in this genus).Many are spectacular flowerers.
Parodia magnifica Parodia of mine (probably werneri) Parodia lenninghausii
Pereskia is a peculiar genus of cactus comprised of very non-cactus looking spiny but notably leafy plants.Their flowers are all beautiful and many bloom all summer long.
Pereskia grandiflora flowers
Pilosocereus is one of my favorite genera since so many are an incredible brilliant blue color (though many are not).Their flowers are interesting but not really too spectacular and tend to do their thing primarily at night.
Pilosocereus pachycladus in my yard
Rebutias are relatively dinky plants often with extremely ornamental spination and forming attractive clumps.But most also have amazing flowers as well.The Sulcorebutias have been lumped into this genus.
Rhipsalis are epiphytes, for the most part and do not look too much like cacti, but are ornamental in their own way.Flowering is usually considered one of those ways, however.
Ripsalis grandiflora (dinky flowers only 1/2" across considering the name)
Schlumbergeras and their relatives are a group of cacti (very un-cactus like) that are truly grown primarily for their amazing flowers which tend to be produced in large numbers around various holidays, including Thanksgiving, Christmas and Easter.
Schlumbergeras in my yard. Last photo is actually of a related genus, Hatiora.
Stenocacti are another of my favorite smaller species as many have fascinating wavy lines down their sides.Their flowers, though not spectacular, are quite colorful and attractive.
Stenocactus species (unfortunately I do not know the names of any of these plants)
Tephrocacti are Opuntia relatives that have fascinating shapes and spines, but their flowers all tend to look the same--nice but not amazing.
There are dozens of other genera of cacti and they all flower, some more impressively than others.However I am less familiar with these other species, and most are far less common in cultivation than those listed above.