Karoo Tree Crassula
1,2 - 2 m
White; spring summer
sun; rockery; windy exposed; walls; slope; dry soils; sandy soils; wildlife birds bees insects butterfly host; narrow spaces;
fynbos; hot & dry; rocky places; cliffs; urban streets
western cape; succulent karoo
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Showcasing some of the prettiest flowers of all the Crassula family, this slow-growing succulent is a must of a water-wise garden or rockery When not in flower the Beestebul, or Karoo Tree Crassula is a softly blue-grey succulent shrub. It takes centre stage though when in full bloom and viewed from close-up, the flowers are quite outstanding. The soft blue-grey leaves are the perfect foil to lift the white starry flower-heads which are massed above the leaves, quite large in comparison to the leaf size. Mature height is between 1.2 and 2 m but it is a slow grower that, luckily for us, flowers while still small. Distribution and habitat: according to the Red List of South African Plants, Crassula arborescens subsp. arborescens is endemic to the Western Cape, from Vanrhynsdorp to Prince Albert, in Fynbos and Succulent Karoo biomes. The SANBI site Plantzafrica offers the following distribution and habitat range: ‘Crassula arborescens subsp. arborescens occurs from the Hex River Valley to the Little Karoo and then further north as far as KwaZulu-Natal and Swaziland. Something rather unusual is that one population of this subspecies occurs on some hills north of Vanrhynsdorp and thus shows a gap in the main distribution which is in the Little Karoo.’ In the wild, they often cover large areas on hills, slopes and cliffs, as well as in as long as the situation is sunny and exposed. Plants growing on slopes or cliffs are often broken by passing animals (even goats) losing parts of branches and leaves, but as with other members of the CRASULACEAE family, they root very easily from broken parts, which often then form new plant colonies. These can be quite close to the mother plant, and dense stands can develop this way. Description: the Beestebal can form a thick, short trunk of up to 1 m tall and often as thick as 20 cm wide at its base. Numerous branches form off the stem to create a well-balanced canopy off which the thick, fleshy leaves grow. These are a blue-grey in colour, with a waxy coating, with a rounded tip usually tapering towards the base. Leaf stems (petioles) are short or even absent. Margins are outlined in a thin reddish trim and red spots often cover a portion of the leaf surface. Leaves are between 20 – 30 mm wide and slightly convex. C. arborescens subsp. arborescens has a few water-wise adaptations: Old leaves will fall off, leaving the shrub rather bare at times; this aids the plant in saving water which it stores in the leaves; a shallow root structure enables it to make full use of even the slightest rain shower, leaves are held erect and upward to reduce the surface area exposed to the sun, preventing the leaf surface from drying out, and the leaf colour and waxy coating helps both to reflect the sun off the surface and help it to keep cool in the heat of the day. The beautiful flower clusters form large rounded heads which are held on stalks slightly above the leaves from spring to summer. The tips of the anthers end in tiny purple dots, like pinheads, and a close-up view shows a star-shaped corolla, usually white, but with soft touches of a reddish-pink brushed onto the surface like a watercolour painting. The contrasting blue-green foliage gives the soft white/ pink colour palette a chance to shine. Flowering is often quite prolific and the entire leaf canopy can be covered. Each flower is made up of 5 petals, each 7 – 10 mm long. Flowers are nectar rich and bird pollinated, but also attracts a variety of other insects, including bees and ants. Flowers turn brown as they dry out after pollination, and the tiny seeds that form split open and are dispersed by the wind. Originating in rocky, stony soils, the Beestebal needs good drainage and air ventilation. If conditions are too moist, leaves can turn blackish. Similar in looks and growth habit to Crassula ovata, C. a. subsp. arborescens does just as well in a container with a well-draining soil mix and full sun situation. Plant in full sun year round. Propagation: will root easily from stem cuttings 5-8cm long stem cuttings or basal offsets. Water the cuttings or the offsets moderately, just enough to make the potting mixture thoroughly moist and allow the top couple of centimetres of the potting mixture to dry out between watering. When the cuttings are well rooted – in about three months – move the young plant into one size larger pot of recommended potting mixture and treat it as a mature plant. An easy and successful method is to simply push a broken piece into the soil close to the mother plant where conditions are favourable for growth. Otherwise, seed can be sown in a sandy mixture. Keep in light shade and damp until they germinate. Keep moving into brighter light as they grow, then sun to harden off before planting out into the garden. It is a perfect choice for drought tolerant and succulent gardens, or position at the back of a rock garden. Mass them to form a water-wise groundcover on a rocky slope. Crassula arborescens subsp. arborescens has been in cultivation since about 1730 but was originally described as Cotyledon arborescens. Only in 1798 was it given the name Crassula arborescens.