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Have you ever heard someone say, “All cacti are succulents, but not all succulents are cacti?” Have you ever wondered what the difference is?
Well, in the most basic sense cacti are succulents that do not have leaves. However, the mere presence of spines (the prickly part of cacti) is not the sole indicator that a plant is a cactus. The various families are actually determined by flower form (just like the orchid).
Needless to say, there is confusion about the differences, and the term “succulent” simply refers to plant tissue that is fleshy and full of liquid (thus giving the plant the ability to store extra reserves of water). Of the 1,000 or so different cacti species, however, most are spiny. The absence of leaves is actually an adaptation that allows cacti to persist in dry, hot and sunny environments.
Plants lose moisture through their leaves, so cacti in arid regions reacted by doing without leaves, producing spines instead. The spines protect the plant from animals that may seek out the water retained within the plant. The thick, waxy coating that protects the plant tissues from drying out also helps reduce the amount of sunlight and heat that are absorbed, creating the perfect desert plant.
There are cacti, however, that have evolved in tropical rainforests. Under these moister conditions the cacti have lost their ability to produce spines and have readapted to producing leaves. Those cacti that evolved in rainforests need their leaves to transpire the extra moisture from the plant and for increased photosynthesis.
The Cholla, barrel, Sahuaro, prickly pear and agave were among the most common cacti that I came into contact with when I lived in Tucson, Ariz. It took awhile to get used to such a different landscape, but after about a year of trying to learn a new way of gardening, the cacti of southern Arizona began to make more and more sense. I was successful growing cacti while in Arizona, but my experiences as a child in Louisville were a bit different.
When I was about 7 years old, my dad went to Phoenix for a Farm Bureau meeting, and he brought back little cacti as presents for my sister and me (having Fred Wiche as a father meant we often got plants as presents!). I killed mine in a matter of weeks. I have since perfected my approach to cacti.
The problem, of course, was the fact that I watered it every day. Thirty-five years later, I can grow cacti in Kentucky.
Actually cacti are the perfect houseplants. The low humidity of the arid desert is just like the low humidity in our homes, especially during the winter months. Unlike other tropical houseplants that usually fill our homes, cacti do not suffer from low relative humidity. Dry and sunny will do.
I have some beautiful Kalanchoe that spend their days outside on the patio in the summer and their winters inside where pink-tinged vermillion pads add a bright spot to the kitchen.
If you want some houseplants that will look good all winter, try some succulents and cacti. Burro’s tail, jade, hen and chicks, crown of thorns, string of hearts, Kalanchoe, Madagascar palm, aloe and any number of other cacti will prove tolerant of dry conditions as long as you have plenty of bright light.
Cacti and succulents should be potted in a coarse medium to ensure good drainage. Let them dry out completely between waterings, and fertilize as you would other houseplants but at half strength.
Cacti should receive as much direct sunlight as possible so a southern exposure is ideal. Succulents are more tolerant of lower light levels. They are also shallow-rooted, so take care when moving them around.
If you put them back outside for the summer allow an adjustment period to avoid burning the plant’s tissue. Be especially mindful of succulents during this transition, because they are even more susceptible to leaf-burn. I’ve done it, and it took the entire summer for the plant to recover.
Check out gardening columnist Jeneen Wiche’s work at www.SwallowRailFarm.com. You can find her columns also at www.SentinelNews.com/agriculture. She answers questions once a month in SentinelNewsPlus. To submit a question, send an E-mail to firstname.lastname@example.org type “Sentinel-News” in the subject field.