All posts by Bridget Laue

Fern Fan visiting RBGE

A few months ago, Dr. Chad Husby visited RBGE (the Royal Botanic Garden in Edinburgh).  Chad is a botanical horticulturalist at Fairchild Tropical Botanic Garden, Coral Gables, Florida, with a particular interest in ferns and especially Equisetum.   He was particularly interested to see the Equisetum collection at RBGE, and was able to identify an unusual horsetail that Gunnar Ovstebo had collected in California, that turned out to be Equisetum x ferrissii Clute, the hybrid between E. hyemale x E. laevigatum.

More recently, I have been reading Chad’s paper ‘Biology and Functional Ecology of Equisetum with Emphasis on the Giant Horsetails’, Botanical Review (2013) 79:147-177.  It includes a discussion of the ancient history of the Equisetum and their now extinct relatives (Sphenopsida) which were the principle vegetation of terrestrial habitats during the Upper Devonian and Carboniferous periods, when the continents were very warm and wet.  These plants became the primary components of the coal layers.  A remarkable feature of modern horsetails is the extent to which they have retained characteristics of their ancient ancestors.

Something that surprised me was that, even though these ancient horsetails grew to enormous size – up to 20 m tall and 60 cm in diameter – they were not made primarily of lignin.  I had always understood that the invention of lignin was one of the major factors that allowed plants to live on land by providing support and allowing for water transport. Incorporation of high concentrations of silicon within cells walls may have contributed to the mechanical strength of the stems, consistent with the high requirement of silicon among Equisetum.  Quite possibly, the horsetails were eventually outcompeted by other plants that had acquired lignin.

Chad’s work has focussed on the giant horsetails in Mexico and South America (see photo of Chad with the E. giganteum Lluta Valley from the Atacama Desert in Chile), of which there are two species E. giganteum and E. myriochaetum (and their hybrid E. x schaffneri).  E. giganteum reaches 5 m tall and has the broadest range, north to south and east to west, of any Equisetum in Latin America. These giant horsetails are mainly found at higher altitudes and in recently disturbed sites, apparently because they cannot compete well against a dense vegetation of angiosperms. Part of their secret to success is the massive rhizome system underground that can survive surface disturbance and can regenerate.

Well, there is a lot more fascinating information in the paper.  I am hoping that Chad will visit again and have a chance to meet more BPS members!

Royal Botanic Garden Edinburgh

I think that I am a very lucky person. One of my projects in my retirement is to spend two days a week volunteering at the Royal Botanic Garden, Edinburgh. And the best part of these jobs is that they involve FERNS!
One of the days I work in the herbarium, with Sally King and others. My project is to begin the daunting task of ‘curating’ the fern collection of Christopher Fraser-Jenkins – something like 40,000 specimens! Yes, it’s unlikely that I will live long enough to complete the project; even if we find another volunteer to help me.
So every week, I examine beautiful preserved ferns – and lycophytes – from places like Ukraine, Russia, Sweden, Spain, USA and Canada. Once I have prepared and labeled the specimens, they are sent for mounting, and the results look like works of art. These mounted specimens then must be barcoded and laid away in cupboards – in exactly the right order and place!

My job on the second day is to help in the Arid house and the back-up (behind the scenes) arid house, under the guidance of Gunnar Ovstebo. Among the living collection of arid tolerant plants are the lovely desert ferns. Many of these specimens have been collected by Gunnar on expeditions to Texas and California and grown from spores. This week the glass houses were closed to the public due to broken glass caused by the dreadful winds we have experienced recently – Gertrude, Henry, Imogen, Jonas …. But we have been able to take advantage of that closure to do some spring cleaning – and weeding! Sadly a few of the ferns don’t look very happy. The winter has just been too extreme with dampness and lack of light as a result of the storms.
But already the Arid house is looking much better. Definitely worth a visit!