Parasites on Proteas
The Balanophore Family has two species which specialize on proteas - Mystropetalon polemanii and thomii - these are entirely underground plants, which only emerge to produce red spikes of flowers. Called Aardroos, these two species appear to be restricted to Protea, Leucadendron and Leucospermum. Dispersed by ants, and pollinated by birds, it has obviously been closely associated with proteas for a long time.
The Santalaceae are a family of root parasites. How many of the 8 species of Thesidium, 80 species of Thesium and Cape Sumach Colpoon compressum, suck sap and water from proteas will probably never be known. Most of these species seem able to tap into any poor plant in their vicinity, and with no known host restrictions, this would include proteas nearby. It is not known if the plants (which are 'normal' above ground) take only water and nutrients, of if they take sap as well.
Whereas, the above two families require excavation to detect parasitism, others are far more obvious. Easily observed as "feeding" on proteas is Cassytha "False Dodder, Devil's Tresses, Nooienshaar", but this feeds on any plant it can get its haustoria onto. Fortunately, this species is killed by fire, and being bird-dispersed, is only really abundant near forest patches and in old veld. Almost impossibly, it belongs in the same family (Lauraceae) as the Stinkwood, Ocotea bullata.
Recently we have recorded two new families on proteas. The Kamiesberg Vexator Ve alpina grows to a ripe old age where fires and fire-wood collectors have not killed the plants. Plants of 4 m height and diameter can be found. Most of these gnarled old plants are festooned with Viscum sp. (capense?) Voelent (in the Viscaceae or Birdlime Family). These are obviously dispersed by birds and become established on the older plants, especially where they are the only sizeable bushes in the area. Some bushes have quite a large number of Viscum parasites.
Similarly, David Osborne found a significant infestation of Tapinanthus Mistletoe (Loranthaceae) on a Pr caffra bush. Given the size of these proteas in the grassveld landscape, it is somewhat surprising that these plants do not harbour large numbers of bird-borne parasites. Part of the reason may be that birds typically do not disperse the fruit over large distances. Most birds squeeze the seeds from the fruit before eating them, carefully rubbing the seed off an a branch to separate it from the sticky pulp. A few swallow and regurgitate the seeds a few seconds later. The larger birds, which do swallow them whole, defecate them within minutes, carefully wiping their behinds on a branch to get rid of the gooey sticky seeds. Thus, few get to land on proteas. But once established, hundreds of fruit will be rubbed off onto nearby branches. Thus parasitized plants, often have serious problems, with hundreds of plants on a bush. One would imagine that fires are the saviour of most proteas, eliminating these bird-dispersed parasites from most Fynbos areas. However, plants nearer forests may be used as stopovers by birds and become infested.
Could atlassers please look out for more records of infestation by parasites. These will probably be rare, but may cause confusion when the proteas burst into bright red flowers or sport round fleshy fruit. If you know of any other protea species playing host to these parasites, please let us know.
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