Spiderheads under threat

In my last post for the year, I thought I'd revisit one of my favourite botanic gardens and one of the more extroverted plant families, the Proteaceae. You can see just some of the flamboyant blooms of this family in this shot of Kirstenbosch National Botanical Garden as the mist rolls back off Table Mountain in the background. We are in Cape Town, South Africa, in August 2018.

The genus is Serruria is perhaps a little less showy. I 'discovered' the genus among the extensive of proteas and their relatives on display Kirstenbosch, back in the days we could travel overseas freely. 

Serruria

The common name for Serruria is spiderhead (spinnekopbos in Afrikaans) on account of the often hairy leaves that look like they are covered in spiderweb. When I saw one in flower for the first time at Kirstenbosch, I thought it was a Grevillea, one of our spider flowers. In fact the species I saw looked very like the Grey Spider Flower, Grevillea buxifolia, from coastal New South Wales. Or perhaps this less well-known, Woolly-flowered Grevillea, Grevillea pilulifera, from just north of Perth.

The Australian Grevillea pilulifera (Woolly-flowered Grevillea) with flowers a bit like those of Serruria

Not so much in leaf though. One of the distinguishing features of the genus Serruria is the foliage, which is unlike most Grevillea species (there are a couple that might get close but not really the same).

Serruria

The spiderhead has leaves more like the Western Australian Silver Woolly Bush, Adenanthos sericeus, which is not too far away from Serruria in the evolutionary tree within Proteaceae. 

The Australian Adenanthos sericeus (Silver Woolly Bush), a close relative of Serruria with similar looking foliage

The leaves of Serruria are, as you can see in this next picture, are similarly finely divided, with cylindrical and usually hairy segments.

Serruria

According to the interpretation sign in Kirstenbosch, there are 55 species of South African spiderhead, almost all of them (48!) - sadly - threatened with extinction. The genus was named after James Serrurier, a Professor of Botany in Urecht, in The Netherlands. So that tells you more about the cultural history of South Africa than about the plant.

As with many Australian Proteaceae, the seeds are carried off by ant who eat the nutritious oily appendage (elaiosome) leaving the seed underground where it is protected from fire and other predators. Again as with some of their Australian relatives, bushfire will kill the parent plant and stimulate the seed to germinate. That was until the invasive Argentinian ant arrived in South Africa, competing with local ants, meaning less seed is stored safely underground.

Serruria

Many of the species have papery bracts around the flower cluster, like in the genus Protea. In fact one species, Serruria florida, is widely used in floristry where it is called Blushing Bride. Others, such as my featured species, are more like a mop of unruly hair. This one is, I think, Serruria aemula, the Strawberry Spiderhead, or a closely related species.

If I have the species right, it is one restricted to the area around Cape Town (as are many Serruria species) and close to extinction due to the destruction and fragmentation of its habitat which now mostly exists under powerlines. Stawberry Spiderhead is being grown in large quantities by Kirstenbosch to replant where the last remaining habitat and plants survive.

Even if I have the name wrong, given the high number of threatened species in this genus (87%), there is a high chance something very similar could be said about this particular plant.

On that sobering note, let's bid the year farewell. And good riddance! Here's to a better 2021...

Table Mountain from Cape Town, early morning