RICHTERSVELD NATIONAL PARK - VEGETATION: KOKERBOOM  
     
  Several species of quiver trees (Aloe dichotoma) occur in the Richtersveld. These peculiar trees are similar to the other famous African tree, the baobab, as they also appear to be growing upside-down. Green succulent “leaves” sprout from the top of many root-like branches. These branches are hollow and the San people used them as quivers for their arrows, thereby naming the tree.  
     
 

The bastard quiver tree casts a dramatic shape on the desolate skyline of the Succulent Karoo in southern Africa. This succulent tree can be up to ten metres tall; there are only a few branches high up on the trunk and reaching skywards, whilst the leaves tend to droop down.

Male trees are recognisable by their bright yellow flowers, about 3 cm long, that grow close to the leaves in winter. Female trees have light red cones, dotted with green. Wind, and desert whirlwinds known as ‘dust devils’, are mainly responsible for pollination. It is believed that insects, attracted by the sweet nectar of the flower, are also responsible for pollination, but this has not yet been established as a fact.
The canary yellow flowers occur in winter and are held close to the leaves, not nearly as showy as many other species of aloes. The outstanding profile of a mature plant more than compensates for any toned down floral display. The copious nectar of the blossoms draws birds and insects as well as baboons that can strip a tree of its flowers in a short time. Being one of the only tree forms in its arid habitat, Aloe dichotoma oftentimes plays host to huge colonial nests of social weaver birds.

The scientific term for ‘forked’, ‘dichotomous’, is the origin of the Aloe dichotoma’s scientific name. At a certain point, while young, the trunk of the quiver tree will divide into forks. As these forks grow, they will divide again, until the mature quiver tree has a tall, wide trunk and a forest of forked branches at the top covered in leaves.

The bark of the quiver tree is smooth and light coloured. The bark on the trunk is normally a golden-yellow colour. It grows in a way that resembles scales with very sharp edges. The branches are lighter and covered with a powdery white substance that reflects the hot sunlight away from the tree, and helps to keep it cool.

The bastard quiver tree is mainly confined to intensely hot and arid areas of the Succulent Karoo biome which receive winter rainfall which may be supplemented with fog precipitation. It grows on rocky, gravel slopes of mountain summits and occasionally on sandy plains.

 
     
 

Little is known about the reproductive biology of the bastard quiver tree, but the species' flowers appear in early summer (around October), and their structure suggests that they may be pollinated by sunbirds. If this is the case, then the bastard quiver tree is one of very few species in the area that is bird-pollinated and therefore plays a key role within the ecosystem.

These trees are a keystone species of this region; many animals rely on their existence for a variety of different reasons. It is one of very few high points in this desolate vegetation that can act as a vantage point for birds of prey and as nesting sites for other birds. The succulent nature of the leaves and flowers is also an important source of moisture for a range of different animals.

Due to the absence of growth rings in this monocot species, it is very difficult to tell how long trees live. It is suspected, however, that they grow very slowly and live between 250 and 350 years.

 
     
     
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