If you are a gardener, you have often heard the term, “succulent”. You might have asked yourself what exactly is it that makes a succulent? You know that cacti, aloes, agave, and tree yuccas are part of this class, and it even includes the towering Queensland bottle tree. How is it possible that these essentially dissimilar plants can all be classified as succulents?
Definition of Succulent
According to the Encyclopedia Britannica (https://www.britannica.com/plant/succulent) succulents are “any plant with thick fleshy tissues adapted to water storage.” Succulent plants are often found in dessert or locations where water is scarce or extremely seasonal. Most of them either have roots that reach widely or that plunge deep to find the life-giving fluid. In addition, they not only have a specialized method of storing moisture, they also have a specialized co2 release system that helps them retain moisture during the heat of the day or the hottest seasons. A good example of this is the way the Queensland Bottle Tree will drop its leaves during the hot summer months, and seem to regain life as soon as the rainy season starts, putting up bloom stalks and growing new leaves.
The Encyclopedia article goes on to point out that there are more than sixty different kinds of succulent species, which certainly explains why these disparate kinds of plants can all still be classified as “succulent.” The good news is that, as gardeners, we have a wide choice of succulents, most of which can be planted in areas that would have a hard time supporting ordinary plants. Many of them are best suited to tropical or desert areas where the days are hot and the nights are chilly, but very few will withstand prolonged cold weather.
Succulent Feature Plants
To discover more about the characteristics of succulents, let’s examine five types of succulent plants, most of which are highly prized as central features for rock gardens or low-water gardens. Each has characteristics that make it a striking or attractive plant to have in your landscaping scheme.
- Golden Barrel Cactus. Originating in Mexico, and considered endangered in their native landscape, golden barrel cacti are in no danger of dying out. Thanks to its unique, attractive appearance it was being cultivated as a garden feature or as a houseplant long before the dam that restricted its habitat (and incidentally provided power and a water reservoir for the people living in its vicinity) was constructed.
A golden barrel cactus resembles a green pincushion with a haze of golden pins stuck into it. Each cactus plant is ribbed, and the tops of the ribs grow the yellow spines that give it the “golden” part of its name. There is a circular area on the crown of the plant. When the tubby cactus receives the right amount of sunlight, it will put on bright blossoms that grow on the circle, then later on, the cactus will put on fruit. A single golden barrel cactus or a cluster of them will make an attractive addition to your low-water garden.
- Tree Aloe. (Aloe Barberae) Tree aloes originate in on the eastern coastal area of South Africa. It likes to grow on well-drained hillsides where temperatures typically stay above 25 degrees Fahrenheit. This means that it can withstand some chilly nights but prefers warmer temperatures most of the time.
A tree aloe grows slowly but will eventually reach twenty to thirty feet in height. This certainly qualifies it as being one of the biggest plants in your succulent bed, and therefore an excellent centerpiece. Its fleshy “leaves” resemble an aloe vera stuck on the end of a tree branch. It serves as a shade tree during the day, so plan the rest of your succulent garden accordingly.
Tree aloes can be grown in a pot where they will make an interesting plant to add to your indoor container forest.
- Queensland Bottle Tree (Brachychiton Rupestris) Queensland bottle trees should not be confused with baobab or boab trees, which are also sometimes called bottle trees. Although both are succulents, the baobabs have scientists concerned about their future, whereas b. rupestris, the Queensland bottle tree, has many thriving members.
The Queensland bottle tree is a dry weather deciduous tree. This means that when the weather is hot and dry, it drops its leaves. This cuts down on respiration that might lose precious water into the air. Unlike the tree aloe, which has fleshy leaves in which to store its water reserves, the Queensland bottle tree stores liquid in its trunk. This will cause the trunk to swell into its characteristic wine bottle shape. When planted out of doors, it makes a beautiful shade tree since as soon as spring arrives it puts on showy blossoms and new leaves. It is best planted where there is plenty of room around it.
- Tree Yuccas. (Yucca Filifera, Yucca Rostrata, Yucca Brevifolia and Yucca Jaegeriana) Although they might look like a tuft of grass on a stem or branch, tree yuccas, like their cousins the yuccas that grow close to the ground, are succulents. Unlike the bottle tree, which stores moisture in its trunk, or the tree aloes that store moisture in their fleshy leaves, yucca plants of all kinds store their extra moisture in their roots. They have a long, thick tap root that reaches deep into the ground, as well as runner-like rhizomes that snake away from the base of the trunk.
Yucca leaves are stiff and have a sort of trough running down their center. This helps channel any available moisture toward the roots. Although they will put out bulbils that might be relatively easy to dig up, getting rid of a yucca plant is actually rather difficult as it will tend to put up baby yucca plants from its roots as well as from fallen seed.
Because of its way of storing water in its roots, it is extremely important that all types of yucca have good drainage. They are not particular about soil nutrition, although they will appreciate it, but water that collects around the roots or around the base of the plant might cause a fatal case of root rot.
In spite of it relative toughness, certain types of yucca plant are on the endangered plant list, especially the Joshua tree (Yucca Brevifolia and Yucca Jaegeriana). Here at Designer Trees, we have Yucca Filifera, and Yucca Rostrata, two of the more common types of tree yucca, for sale. It is possible to legally purchase a Joshua tree, although the more usual term is to “adopt” a Joshua tree. As with all rare or endangered species, you should only purchase trees that properly grown or collected by licensed nurseries, such as ours. Such trees are tagged with an indication of where and how they were obtained.
Succulents are amazing plants that can grow in places no other plant will tolerate. With that said, they have their own special requirements, and are not completely maintenance free. They are usually lower maintenance than many other sorts of plants. Keep in mind that more succulents have died from over-watering than any other cause, and that they will all benefit from a little benign neglect.