While a cactus might not be the first thing that springs to mind at the mention of flowering plants, there are many kinds of cacti that sport more than just spikes and spines. These evergreen succulents can blossom with some of the most breathtaking creations in the desert, and sometimes it's necessary to know where to look.
Cacti produce very distinct flowers, and this is part of what separates cacti from other similar-looking succulents.
The outside layer of the cactus flower is always--regardless of the type--a layer of stem tissue. Called leaf primordia, this layer is often a precursor to the plant's production of the flower, called sepal primordia. Typically, between 20 and 30 of these leaves are formed before the flower begins to develop. Some cacti will form leaf primordia without forming flowers; in this case, the leaf primordia are not as large or well developed.
These leaf primordia are considered actual leaves in the same way a maple leaf is.
Cactus flowers actually grow inside out. In non-cactus flowers, all the inner parts grow at the same rate. However, the inner part of the stem of cacti flowers has a growth rate slower than the outer cortex of the flower. Because of this, what looks like the flower is actually stem and leaf parts; all the flower parts--including petals--are located on the inside of the flower.
Other succulents are frequently mistaken for cacti, and one way to tell if a plant is a true cactus is to look for a pattern at the base of the flower. The areole is a circular arrangement of spines, located where the flower will begin to bud.
Succulents such as the crown of thorns and the cow's horn cactus have all the other requirements of being a cactus, but they are not considered as such because their flowers lack this radial arrangement of spines at the base.
Many cactus flowers only bloom at night. Cacti are well suited to survival in the unforgiving heat of their desert habitats, and night blooming is another adaptation. Like other flowers, cacti flowers are pollinated by birds, moths and other insects. Because of the extreme heat of the desert in daytime, these creatures typically make their appearances at night. Blooming at night allows the cacti to take full advantage of attracting these creatures for pollination.
Not all the flowers found on cacti are real. Many retail stores attach fake "real" flowers to a cacti to help grab the attention of shoppers. Thinking that they would often overlook a plain, prickly cactus, they attach a flower commonly known as a strawflower or an everlasting. These flowers have a unique characteristic: after they are dried, they still continue to open and close, making them look like they are real cactus flowers.
They are often attached with pins or hot glue guns, and have a life span of about a week. Those interested in purchasing a flowering cactus should do their research, and look carefully at those cacti that look to be in bloom.