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Plant Profile Echium pininana

When composing Blogs on plants at VBG it’s often easy to overlook the obvious through familiarity.  Perhaps a plant for which this botanic garden is rightly famed is one that we don’t tend, plant, propagate or molly coddle.  It has grown, as though wild, here for over thirty years.  It has been seen as so symbolic of the garden that it even, briefly, flirted as our logo for a short while though some considered its twin spikes emblemic of some darker purpose.  Without doubt it is the plant which we are asked the name of more than any other and I have long thought we should wear shirts simply bearing the legend “It’s Echium pininana”.

It is easy to see its popularity, flower spikes with tens of thousands of tiny blue flowers much beloved of bees raised to heights around 3m.  I suspect everyone can remember the first time they saw one, and many would have been here.  My first encounter was in Cornwall, with a group of keen students from Kew, Hillier’s and Wisley touring gardens and viewing Magnolias, where there was one growing from a dry stone wall outside of Trebah.  Nobody seemed to have any idea what it was except Barry Philips who told me it was an Echium.  I thought he had lost his mind, Echium to me was the Vipers Bugloss of chalk downland, it wasn’t till closer study that the real story of Echium pininana revealed itself.

Echium pininana evolved in isolation in the Canary Island group, specifically the island of La Palma.  The Canaries, for so many reasons, not least being islands that have never had a land bridge, have a fascinating plant ecology with roots in the northern European flora.  Familiar plant genera and families have representatives that have evolved in isolation into ecosystems quite different from their relatives, thus Echium – known to me as the short but showy wildflower – has changed into new and different types.  Echium pininana found its natural niche at the uppermost limit of the lauraceous forest ascending the central caldera.  Speculation is that in this splendid isolation it adopted through natural selection the characteristics familiar to some fascinating plants at altitude, that of gigantism.  Gigantism is seen at a particular altitude on mountains throughout Africa and South America.  Plants have developed that are of monstrous size, especially in their trunks.  It is speculated that this has happened in response to the harsh environment, a lack of competition has allowed these lonely giants to monopolise the scant nutrient resources.  The likelihood of successful regeneration is pitifully small, so they have also adopted a strategy of producing hundreds of thousands of flowers, and thus seeds, in the hope that a single one over a lifetime of many, many years will succeed.  E. pininana’s strategy is somewhat more of a gamble, reproducing once in its biennial life.

Natural populations of Echium pininana before the arrival of man were thus precarious, though stable.  The earliest arrival of Europeans, though relatively undocumented, had a profound impact on the balanced ecology of the island.  For two thousand years our species has exploited their island environment degrading the laurel forests to the point where habitat loss has pushed Echium pininana into a precarious position in the wild state, and yet in cultivation it is often considered a weed.

At Ventnor Botanic Garden the current self-sustaining population of E. pininana was introduced by Simon Goodenough in the 1980s (there is evidence of earlier experimental plantings before this time, but the plant would have been considered something of a trophy in the unevaluated microclimate that was still to reveal its true potential.  Most likely it simply wasn’t given the opportunity to seed by the overenthusiastic and very gardenery gardeners of that time).  Simon’s plants were sourced from the Canaries’ botanic garden and produced a stable population that was remarkably pure, so much so that they were the group of study for Mike Maunder’s PhD in the 1990s.  Sadly, from a purist’s point of view, it wasn’t long before a tom got in with the pedigrees.  Another species, the red flowered Echium wildprettii, from Tenerife, hybridised with the E. pininana.  From that point onwards we have had a hybrid swarm at VBG; the flowers of our giants are now a little murkier than the sharp blue of the true species.

In context, this hybridity isn’t necessarily a bad thing in some ways.  Consider the precarious natural populations of E. pininana (and its neighbour E. wildprettii, or the other neighbouring species for that matter – there is almost one per volcano).  It is in their best interest to keep the door open to cross pollination and potential hybridity as new genetic material could offer an advantage to future populations.  Therefore these species are non-obligate outbreeders, they can self-pollinate, but given the opportunity to cross with another plant – they will take it.

Later introductions of new Echium species have increased the hybridity of our populations.  The introduction of the shrubby, branched E. fastuosum saw hybrid plants that become ungainly.  This is an example of where new genetic input has resulted in plants that do not have an advantage, the sheer weight of plant matter that the E. pininana genes drive coupled to the branching that the E. fastuosum genes bring to the feast make a plant that breaks apart under its own weight.  This is an example of natural selection in action; these hybrids are poor and unlikely to succeed to pass on their genes because the plant fails before maturity.

From a horticultural point of view Echium pininana is a winner every time.  Commercially, our hybrid plants are big sellers both as plants from Jason’s nursery or as packaged seed in our seed shop.  As a scientific study there has been one PhD gained already, there is certainly evidence enough for fascinating future study of its breeding system and those of its close relatives.  A very new speculative hybrid (E. pininana x E. gentianoides) looks very interesting indeed, it is a hardy perennial, giant, and has Gentian blue flowers in Chelsea week.  If E. pininana has any drawback at all…it simply needs a good common name.

“Excuse me, what’s the big tall blue flower like a Lupin?”

“It’s an Echium pininana

“An Ekky mum?”

ek’-i-um

“Does it have a common name?”

“I’ll write it down for you”

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