A thorn is a thorn is a thorn

PHOTOS: Lien Botha | WORDS: Dave Pepler and Allan Davies

The prick of a thorn is a reminder of our fragility, but it’s no accident that plants with thorns are among the most beautiful of all, because each one has something precious to lose or hide.

The Bible’s Old Testament bristles with references to thorns. You have only to look at Cruden’s great Bible Concordance, in particular Isaiah 34:13: “And thorns shall come up in her palaces, nettles and brambles in the fortresses thereof: and it shall be a  habitation of dragons, and a court for owls.” Thorns and thistles were a curse more fearful even than death or the plague. Thorns infested the humble patch of the first farmer, choked the crops, ruined the pastures. For the nomads of long ago, spring was a fleeting abundance; as the summer briars took hold, they had to move on, flee.

How and where did thorns come into being? Primitive  plants all had their origins in the algae. But somewhere in the past some of them became more palatable, and so more sought-after. And this is where the arms race began, when incidental thorns gave certain plants a better chance of survival. Plant eaters had to adapt, developing small mouths to graze  between the barbs and robust teeth to crack them. Thanks to this ecological tug of war, today we have some of the most beautiful plants on earth: the acacias, the heavenly euphorbias of our deserts, the silk thistle and the rose.

Consider, also, Africa’s classic thorn trees. You have only to look at the silhouettes. There is nothing accidental about these divine shapes, because they have been carved out by others in search of the tree’s hidden treasure. Under the goad of the spines the lower layer has been pruned away and the crown compelled upwards. The whole landscape is defined by the finer detail, rather than by the big picture – the sky blue as nowhere else on earth, the forms pure Pierneef.

If I had to choose my favourite thornbush it would be the num-num. Was there ever a more rewarding and generous garden plant? You wake one summer morning with the bedroom windows open to the garden. The curtains billow and suddenly you’re enveloped in a cloud of the purest perfume. It reminds me of Guerlain’s Vetiver, as described by Luca Turin: “Stoic and discreet, Vetiver scorns all luxury save that of its own proud solitude”. Later in the season, you are rewarded yet again with the ripening of the num-num’s startling red fruit. Sweet and sour hidden among the double thorns. 

We tend to forget that our world is a thoroughly prickly one. From the rose on your coffee table, the berries in
your yoghurt – blackberry and raspberry – and the sweet chartreuse-green prickly pear, to the landscapes of Africa passing your car windows, from fynbos to Kalahari – thorns are everywhere.

A prick of the finger reminds us of our frailty. First the
electric sting, then weakness – then the drop of blood, round and perfect. Redder than coral, num-num red. There is a beautiful verse, “Lascia la spina”, from Handel’s oratorio Il trionfo del Tempo e del Disinganno.

– DAVE PEPLER

– Sources: Burr, C. – The Emperor of Scent, Arrow Books, London, 2002. 

Ministry of Defence

 In September 1908, Sir Francis Darwin, botanist and son of the great Charles, made a startling claim. In an address delivered to the British Association for the Advancement of Science, he suggested that plants were able to “think” and that, as regards relation to environment, they and humans must therefore be placed in the same class.

This provoked howls of scorn. Take a look, however, at the defence strategies of plants and you might be inclined to agree. This armoury must count as one of the most extraordinary feats of evolution. Shoots, leaf stems and leaves have been changed into sharp protuberances, some hair-fine, others large as lions’ teeth; some straight, some wickedly hooked, others forked. Over time, a live, soft appendage has become a hard, fibrous one with fortified cell walls, cunningly arranged to repel or ensnare – or both. Botanists refer to these modifications of plant parts as spines, specifying whether they are leaf, shoot, petiolar (leaf stalk) or stipular (a tag at the base of the leaf stalk). There are also thorns that are not modifications of standard plant parts but extra growths, termed emergences or prickles. Rose thorns and surface thorns of aloes are typical emergences. A spine generally contains some vascular tissue; an emergence does not. Mature spines and emergences are usually made up almost entirely of dead cells.

Most of these elaborate defence mechanisms have developed in arid regions, along with other modifications designed to cope with drought. Stems swell to become water reservoirs, leaves become thorns, reducing transpiration as well as protecting the plant from thirsty animals. Other plants, such as acacias, retain their leaves, but the stipules change into large protective spines at the base. The spacing and angling may not entirely deter browsers, but will certainly inhibit them. Other thorns, such as the diabolical Devil’s Claw (Harpagophyton procumbens) and the dubbeltjie (Tribulus terrestris) are designed to catch onto an unfortunate passer-by and so effect seed dispersal. Hooked thorns along stems, such as in roses and asparagus species, are not only protective but also climbing aids.

For all the animals that are discouraged by the barriers of the plant world, there are probably as many who use them as protection. Observe the number of birds nesting in thorny scrub and acacia trees: firm anchor pins to hold a nest – and safe as houses.

The well armed garden

• In the garden, sculptural plants such as aloes, cacti, thorn trees and agaves provide dramatic beauty as well as security fencing, but keep them away from paths, patios and play areas.

• Keep branches of trees well above eye level, or let them sweep to the ground.

• Arm yourself with heavy leather gauntlets for gardening. 

• Aloe arborescens, the cat thorn, Scutia myrtina, the
Kei apple, Dovyalis caffra, or various taller species of Euphorbia, all make striking and impenetrable hedges.

•  If you have space, plant a thicket or exclusion area of thorny trees, shrubs and scramblers, which birds will love.

• Begin by planting thorn trees close together along the boundary. To the front, plant shrubs such as Cassinopsis ilicifolia, and Carissa macrocarpa. Add thorny scramblers, such as Asparagus falcatus and Smilax kraussiana.*

• Spiky exotics also make colourful security hedges and habitats, especially bougainvillea and heritage roses. Gwen Fagan suggests planting a mix of the following old roses for a beautiful display: ‘Géant des Batailles’, ‘Alberic Barbier’, ‘Indica Major’, ‘Mermaid’, Rosa laevigata, Rosa multiflora varieties and ‘Russelliana’.

– ALLAN DAVIES