A remarkable plant
Tropical cacti make excellent subjects for a variety of situations in a greenhouse, conservatory, or outside in warmer areas. While the vegetative form of many is fascinating enough, flowers can be very, very striking, and this species, Selenicereus grandiflorus, is amongst the most striking and has enormous flowers to say the least.
Selenicereus as a genus is distributed from southern USA through Central America, the West Indies, and Northern South America. This species, Selenicereus grandiflorus hails from Cuba. Members of this genus are all climbers or trailers (plants in my own collection trail almost 2 meters). The genus derives its name from the Greek selene (moon) which is in reference to their night flowering habit. Stems are elongated, ribbed or angled, and in nature climb or clamber amongst other plants.
Flowering of my own plants seems to generally occur once a year, around late summer/autumn. Flower buds form on the trailing stems in later summer, and these buds take several weeks to grow. Watching them grow and grow in size leads one to wonder just what the plant is up to. The buds may be up to 20 cm long, and do look like something from a science fiction movie. Eventually, the buds finally open, at night, to reveal a most amazing and glorious flower. The flower is fully 35cm across at least (see photo- the persons hand is right next to the flower!!). Grandiflorus is indeed an apt epithet. Individual flowers last for one night only, but the sheer size and impact of each flower is truly a wonder. By morning the flowers have literally flopped, but on a healthy plant there will be a succession of flowers over a period of many days.
In its natural habitat, bats pollinate Selenicereus, hence the night flowering habit. I suspect that the sheer size of the flowers is also associated with the relationship with bats. Pollination is another fascinating aspect of the life of plants, something I have studied for many years, and something, which never ceases to amaze me. Incidentally, I have never been able to artificially pollinate Selenicereus, so the bats obviously know something I don't!!
In cultivation, I find Selenicereus undemanding. In my heated houses, it seems that a minimum of 8-10 degrees Celsius is all that is necessary. I find that being pot bound suits them best, in an open mix, and an application of half strength Nitrosol or something similar keeps them happy. (I am a haphazard gardener, so they only get fed when I remember!!)
Extracts from Selenicereus are used in cosmetics (essential oils and tinctures). Some herbalists use various extracts to treat symptoms in Reynaulds disease, and asthmatics who have cardiac problems.
This article was kindly supplied by Peter Jensen of Ayn Dara Nurseries, specialising in exotics, poppies, rare and unusual bulbs, perennials and succulents.