Crassula arborescens is a succulent plant belonging to the Crassulaceae family. It is an important decorative plant cultivated for succulent gardens and container gardens. It is highly drought resistant and is also suitable to be grown as a houseplant. This plant is commonly known as the Silver Dollar Plant.
Crassula arborescens Description
The plant is a perennial succulent shrub.
Height: It grows to a height of 2 to 4 feet.
Stem: The plant is single stemmed with many branches. The base of the stem can have a thickness of up to 20 cm. The growth of many branches gives it a small tree-like shape. It has a thick, fleshy trunk covered by a smooth, greenish bark.
Leaves: The leaves are disc-shaped, orbicular to obovate and fleshy. The upper and lower surfaces of the leaves are somewhat convex. The leaves are blue-grey in color with a red margin around the edge. There are red spots in the leaves. A waxy, powdery bloom covers the leaves and protects it from the harsh rays of the sun. The upper end of the leaves have a pinkish mottling. The petioles are either absent or very short. The base of the leaves is narrow and tapering. There is very little variation among the leaves.
Flowers: The inflorescence bloom in winter as well as in the spring and summer months. The flowers occur in dense branches and have almost spherical heads. They have star-shaped corolla. The sharply pointed petals are 7 mm to 10 mm long and are spread at right angles. The anthers are purple. The length of the peduncle varies between 30 mm and 70 mm. The petioles are also quite small in size. During the spring and summer months, the plants are almost entirely covered with flowers. The flowers change their appearance to papery brown after pollination which adds to their scenic beauty.
Fruits: Ripening of fruits occur from the months of November to January. The fruits are small and have a length of around 6 mm. They are comprised of 3 to 5 separate oval-shaped follicles. The follicles have sharp tips and are distributed among the dried portions of petals.
Seeds: The seeds are quite small in size; they are distributed by the wind.
Crassula arborescens Varieties
There are two varieties of this plant which can be endemically found in various parts of South Africa.
- Crassula arborescens arborescens
- Crassula arborescens undulatifolia
Crassula arborescens Habitat and Distribution
The two varieties of Crassula arborescens are found in many parts of South Africa. Crassula arborescens arborescens is found in places such as the Hex River Valley, the Little Karoo, KwaZulu-Natal and Swaziland. The Crassula arborescens undulatifolia is distributed in the southern zones of Klein Winterhoek Mountains in the Eastern Cape.
These plants are mostly found in hilly areas, cliffs, dry valleys and mountainous slopes in different regions of South Africa. These plants grow in sandstones as well as shale-derived soils in rocky to gravel-filled areas.
Crassula arborescens History
The Crassula arborescens plant has been cultivated as early as in the year 1730. The plant was described by Miller in the year 1768 as Cotyledon arborescens and then again in 1798 by Carl Ludwig Willdenow as Crassula arborescens.
The genus name Crassula of this plant is derived from the Latin word ‘crassus’ which refers to their thick succulent leaves. The species name ‘arborescens’ refers to the large, tree-like look of this particular species.
How to grow Crassula arborescens
The various growing conditions for these plants are listed below:
The Crassula arborescens requires bright light and a sunny position to grow well and bear flowers. The ideal climatic conditions for growing these plants would be in the steppes or in a subtropical day low-savannah climate. The plants also need good air circulation which will help the plant in avoiding intense heat on sunny days as well as excessive humidity in moist and wet weather. While moving Crassula arborescens from a shaded area to a brightly sunlit spot, instead of abruptly changing the location of the plant, it should be acclimatized slowly to the new conditions otherwise the leaves might get damaged.
The minimum temperature for growing Crassula arborescens should be within 8°C to 10°C and the maximum temperature should be kept between 24°C and 26° C.
If the temperature goes above 90°F, the Crassula arborescens will stop growing. These plants can even survive cold weathers just above the freezing point provided the soil is maintained dry and frost free.
The cold temperatures during the nighttime promotes flowering.
The plant should be watered thoroughly on regular intervals and be allowed to dry itself out between waterings. Sometimes the lower leaves of the plant may become soft or even get wrinkled. In these cases, the plant may need more watering than usual. Watering these leaves adequately will restore them to their earlier health and make sure everything is alright with the root system.
The soil should not always be kept moist. The plant pot should be placed in a water dish and watered from the base. However, the plant should not be left standing on the water for more than a few hours. The excess water that hasn’t been absorbed by the soil should then be removed.
Some of the leaves might drop off for natural reasons, either due to the heat or if the plant is suffering from dehydration. However, sometimes the plant may shed leaves even if it has been adequately watered. This means that for some reason the root system is having some problems absorbing the water. In such cases, additional watering should not be carried out as that would lead to formation of soggy compost and thereby do more harm than good. The recommended action would be to check the root system for any disturbances. Cases such as these might indicate pest problems or rotting of roots.
While it is not really necessary to spray the foliage with water, occasionally placing the plant outdoors in the rain cleans the dust and helps in freshening up the plant foliage.
Soil and Fertilizer
The Crassula arborescens plant grows best when it is repotted into new soil at regular intervals and the pot size is increased gradually over time. The soil mixture required for the plant’s optimum growth is not very complex and general houseplant compost will do fine. One can create a good soil mixture by adding sharp sand or grit to a standard houseplant compost soil.
Fertilizer should be added along with water during the plant’s growth. The strength of the fertilizer should be a quarter of the recommended strength for the full grown plant. Soil containing low amount of nitrogen is suitable for proper plant growth.
The roots, trunk and branches should be pruned at regular intervals. The roots should be pruned while repotting in a pot of similar size and pruning the stem on specific locations will facilitate growth of new leaves.
Pests and Diseases
The plant may get infected by Pythium blight, Helminthosporium and Fusarium. One should watch out for pests like Round Scale (Coccidae spp). It is important not to use pyrethrin-based sprays like Malathion as insecticides. Regularly watering the plant with imidacloprid-based systemic insecticide will help in avoiding diseases and pest problems.
Propagation of Crassula arborescens can be carried out from the healthy leaves. The leaf should be placed leaning by the pot’s side. The base of the leaf should touch the top soil. After some time roots will start being produced indicating the birth of a new plant. The leaf should not be watered until the roots start to develop.
Stem cuttings and seeds may also be used to produce a new Crassula arborescens plant. The seeds should be harvested as the fruit ripens and the inflorescence turns to a brown shade. Seeds should be sown in a moist, damp, somewhat sandy soil. However, growing these plants from seeds is something most people not opt for as it is a very slow process. The stem cuttings may be used to grow these plants throughout the year.
Crassula arborescens Uses
The Crassula arborescens plant is used to treat epilepsy.
Crassula arborescens Interesting Facts
Here are some interesting facts about these plants.
- These plants are consumed in Swaziland where they are locally known as Umchobozovithi.
- The white and pink flowers are filled with nectar.
- Apart from bees and other insects, the flowers of these plants are also pollinated by birds.
- A powdery, waxy layer covers the surface of the leaves which deflects sun’s rays and help the plant to stay cool.
Crassula arborescens Images
Here are some pictures showing these interesting plants.
The Crassula arborescens plant is a strong, drought resistant plant. The plant has a beauty of its own and it is also fairly easy to cultivate. These reasons have made the Crassula arborescens plant popular with all gardening enthusiasts.