An island of flowers – Part 5: Monte Tropical Gardens

As promised in my previous post, this is a visit to a nearby but completely different place, the Monte Palace Tropical Gardens.
Located slightly higher (600m above sea level), the Monte hills can be reached by an impressive cable car overlooking laurel forest:

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Where the Botanic Gardens were exposed, filled with cacti and succulents, the Monte Tropical Gardens are cool and shaded, with a splendid diversity of woodland plants. Established on the land of a 18th century quinta, the garden was created in 1987 with a very oriental inspiration. The visit starts with Japanese-like red stairs descending into the valley:

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Water is omnipresent, with little streams and cascades surrounded by Japanese lanterns, ferns, subtropical shrubs such as Fuchsia boliviana and large Clivia. The diversity of ferns and bryophytes is incredible, here’s for example a liverwort that was growing on the side of a path.

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Monte Palace is not just a pretty garden. There are artistic and historical references scattered in the landscape. This is a wall called “The Portuguese in Japan”, which depicts how 16th century Portuguese explorers brought Christianity to south-western Japan:

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The garden is home to one of the largest cycad collection in the world, with dozens of species which are threatened in the wild. Sadly, it appears that the cycads (725!) in the collection were acquired illegally, against CITES regulations by the owner of the property in 1988. I really hope that they are propagating these plants in some way as they have a great scientific value… This is the Eastern Cape Blue Cycad (Encephalartos horridus) which is endangered in its natural range (Cape Province, South Africa).

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As I know that some of my readers are fond of cycads, here are the cones of Encephalartos eugene-maraisii (Waterberg Cycad), also endangered in the wild:

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As everywhere in Madeira (you are probably getting used to them now!), there are stunning views to the sea from various terraces:

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The central lake is a bizarre mix of roman-like arches, traditional Madeiran buildings, cascades…

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but also sculptures like this sphinx and fern-rich walls:

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There’s an orchid promenade, as well as several ponds with koi carps, and to stay in the oriental theme, a large buddha statue surrounded by tree ferns:

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Every wall is covered in greenery – this corridor for example is filled with Ficus pumila. Another interesting idea is the use of tree fern caudices (trunks) as stairs – Madeiran recycling style!

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The rest of the garden is devoted to Madeiran flora and designed to imitate a typical laurel forest. Two examples here: the endemic daisy Argyranthemum pinnatifidum and the Madeira Holly (Ilex perado subsp. perado).

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Next time, I will blog about Madeira’s wild (although not necessarily native) flora. But before that, just to make you all very envious, the view of a roof terrace filled with plants and overlooking the hill…

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An island of flowers – Part 4: Madeira Botanical garden

Reached by a short drive from the centre of Funchal, the Jardim Botanico, located 300m above sea level is a relatively recent botanic garden (opened in 1960), but full of surprises. We start our visit by the spectacular Succulents zone, with the orange flower heads of Aloe striata and red ones of Aloe plicatilis :

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As everywhere in Madeira, there are fantastic views of the sea, this time through the tall stems of true cacti (Cactaceae – Cereus peruvianus for example) and false cacti (such as Euphorbia ingens):

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The succulent garden features numerous South-African groundcovers such as the  daisy-like Glottiphyllum depressum or the prostrate and vicious-looking Euphorbia grandicornis.

Glottiphyllum fragransEuphorbia grandicornis

Going down from the succulent garden, we find a palheira (traditional triangular-shaped Madeiran cottage), surrounded by frangipani trees:

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The next garden is a assemblage of elaborate topiary shapes,  reminding the visitor of famous Italian gardens. Note also the primitive conifer Araucaria heterophylla (Norfolk Island Pine) in the foreground – they are everywhere on Madeira:

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There’s also an impressive collection of cycads:

Cycads

Going back up the slope on the other side of the garden, there’s a display of agricultural plants that can be grown on Madeira, from mulberries and olives to mangoes and avocados:

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Possibly the most famous view of Madeira’s botanical garden is the red and green floral carpet offering a panorama of the South Coast of Madeira:

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Of course, it is still a botanic garden, with many interesting plants to discover. Two purple ones here: the Central American borage relative Wigandia caracasana and the African Ginger Bush Tetradenia riparia:

Wigandia close-up

 

For those interested in science, the garden has a tiny natural history museum, with impressive displays of fossil wood found on the island (trunks of Erica platycodon subsp. maderincola and Apollonias barbujana) and herbarium specimens (a pretty one of the Canary Islands endemic fern Asplenium aureum):

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Nested on one edge of the garden, the “Lover’s cave” provides shade and shelter, as well as offering yet another great view over Funchal:

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And I can only conclude with a picture of the emblematic Madeira Cranesbill (Geranium maderense), a plant which is Critically Endangered in the wild according to the IUCN (because of Madeira’s intensive urbanisation), but very popular with gardeners, even in the UK:

Geranium maderense

 

Next time, a very different place, the Monte Palace Tropical Gardens

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An island of flowers – Part 3: the quintas of Funchal

As this article explains quite well, the simplest definition of a Portuguese quinta is that of a countryside estate with a large house, surrounded by orchards and gardens. Many quintas have been swallowed by developments and incorporated into the urban mesh of Funchal, but they still carry a hint of Madeira’s aristocratic past.

In the heart of Funchal ‘Old Town’, the Quinta das Cruzes, which has been turned into a museum, is surrounded by romantic, 19th century gardens. There are for example very English-looking rose beds:

Rose garden

The rest of the garden however does look more suited for the Madeiran climate, with this stunning Karoo cycad (Encephalartos lehmannii - a South African plant which has been assessed as “near threatened” in the wild) for example:

Encephalartos lehmannii

The orchid shadehouse is full of surprises (not a single label to be found though!):

Orchid shadehouse

For cycad enthusiasts, there’s also Cycas circinalis, an endangered species from Southern India; and for tree lovers, the large, South American Phytolacca dioica with its long white racemes:

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The garden only covers one hectare, but there is plenty to see, from aroids to bromeliads, large palms or tree ferns:

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Even the lawn weeds have a certain exotic look (and exotic origin, as they are both from Southern Africa) - Bulbine frutescens with its fluffy stamens, and the striking Freesia laxa:

Freesia laxa

The second quinta we visited, located on the heights of Funchal, is the Quinta Jardins do Lago. Established in the 18th century, it was the home of the British Commander during the Napoleonic Wars (early 19th century), and I have to say it does have a definite British feel!

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The house is surrounded by themed flower beds, like this one which displays dry-environment flora:

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There are trellis with exotic climbers on every single wall. Here, the red flowers of Clerodendrum splendens, and the large purple Sandpaper Vine (Petrea volubilis - often nicknames “tropical wisteria”) from Mexico:

Petraea volubilis

Pathways are covered with pergolas, like this jaw-dropping one covered with Thunbergia mysorensis:

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Unusual sightings include the South African tree Schotia brachypetala and the (appropriately named!) cup-and-saucer-plant Holmskioldia sanguinea, an Asian relative of our wild skullcaps (Scutellaria sp.):

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I quite liked the gardeners’ choice of plant pots: cut palm trunks and clay pot with holes for orchids!

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And I have to dedicate this post to the local resident, Colombo, a giant tortoise from the Galapagos Islands who was born in 1958, and who has been living on Madeira for over 45 years! He is sweet, isn’t he?

Colombo, a 47-year-old Galapagos tortoise

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An island of flowers – Part 2: the parks of Funchal

As you’ve discovered in my previous post, the flora of Madeira, in particular its capital city Funchal is very diverse.

This is reflected in the numerous parks scattered in the city, and the most famous example is probably the Jardim Municipal. Located in the touristic heart of Funchal, it was established in 1878 on the site of an old convent. It now features benches to relax, an amphiteatre for events and a café where it is possible to sip a local drink under giant ferns and aroids:

Monstera & Colocasia

Flower beds bring colour to the square, with a mix of English cottage plant such as hollyhocks (Alcea rosea), stock (Matthiola incana) or black-eyed-susans (Rudbeckia),  South American bulbs (Hippeastrum - the kind you put on your windowsill in winter!), Central American and heavily scented frangipani (Plumeria sp), and South African coral trees (Erythrina caffra).

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For the plant enthusiast however, it is the trees that will catch the eye, whether they are Madeira natives or exotics. I wonder how old this giant Chorisia speciosa (silk floss tree - native to the forests of South America) is:

Chorisia speciosa

Other interesting trees include the African sausage tree (Kigelia africana – giant hanging sausage-like fruits, that’s a rare sighting in the European Union!) and a large Weeping Bottlebrush (Callistemon viminalis) from Southern Australia in full flower:

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Going towards the sea, the visitor will reach the Parque de Santa Catarina, which offers stunning view of Funchal Old town and of the harbour:

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Once again, there are trees worth noticing: the Kapok (Ceiba pentandra), a Central American tree whose fluffy seed pods can be used to make filling for duvets and pillows; and Schinus molle (the false pepper tree) – its fruits are sold as “pink peppercorns”, although they bear no relation to black pepper (Piper sp.)!

Ceiba pentandraSchinus molle

Being more exposed than parks on the heights of Funchal, the Parque de Santa Catarina is full of dry-loving plants, such as this gigantic Dasylirion serratifolium from Mexico, surrounded by the cactus-like Euphorbia E. ingens on the left; brown-leaved croton Codiaeum variegatum on the right; and tall Yucca in the background.

Dasylirion serratifolium

There is plenty to see on the ground too, with the pink flowers of the Mexican melastome Heterocentron elegans , and the stunning leaves of Farfugium japonicum:

Melastome maybe (2)Ligularia tussilaginea

And because I know you like that, here’s a bit more of Madeira’s blue sky, with a view of the central mountains…don’t worry, I will get you there in one of the next posts!

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An island of flowers – Part 1: the streets of Funchal

This is the first post in a long series on the island of Madeira, where I went on holiday last month. With stunning landscapes and very interesting flora, I’m sure you will enjoy the trip!

Located approximately 500 km off the African coast, and 1000 km south of continental Europe, Madeira is in fact a volcanic archipelago made of 20 islands, only two of which are inhabited : Madeira sensu stricto and Porto Santo. Whereas Madeira is rocky and humid, Porto Santo, seen here from the plane, is very dry, with a large plain in the centre, and a 9 km long sand beach popular with tourists:

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Porto Santo is only 40 km away from Madeira and can easily be visited by boat, but we stayed on Madeira this time! Before venturing in the rest of the island, I wanted to show you the main city, Funchal, which has over 100000 inhabitants. The first thing that will strike the visitor (unless you come from the Alps or know Lisbon) is how hilly everything is! Every road is just sloping more or less gently down to the sea; and this is for example the view that we had from the terrace of our flat:

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Houses are arranged vertically (with terraces, water reservoirs, kitchens etc on the roof) because the streets are often narrow (this keeps windows shaded and helps cool down the houses) and mainly designed for pedestrians:

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Thanks to its geography, Funchal gets a lot of water from the central mountains; so while the air can get dry in summer, the soil will rarely lack water. A very diversified range of trees can be spotted in the city, from the iconic purple Jacaranda avenues, to the imposing Araucaria (New Zealand pines), familiar-looking London planes (Platanus x acerifolia) and dozens of species of palms.

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Abandoned houses are often overgrown with vines such as morning glories (Ipomoea), grapevines (Vitis), or the Balloon Vine (Cardiospermum sp.); and occupied houses require a lot of maintenance work (a brave gardener pruning Bougainvillea, which grows very quickly in Madeira):

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The strangest thing about Madeiran flora, particularly in Funchal, is that almost everything can be grown on the island, which yields strange mixes of plants from the four continents. It is very easy to go in one glance from New Zealand (Agathis sp.), to Africa (Cyperus papyrus), to Central America (Tecoma stans),  and Asia (Pandanus sp.):

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Of course the island has many endemics, and a trip to the (free!) local museum gives a good overview of Madeira’s iconic plants. There were a lot of herbarium specimens (botanist heaven), this is one of the famous Madeiran foxglove, Isoplexis sceptrum. Some Madeiran plants are also widely cultivated, see for example Dracaena draco, the Dragon Tree:

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Gardening appears to be a popular activity among Funchal inhabitants, and even in limited spaces such as this patio, Madeirans have found clever ways to grow flowers and edibles – such as these recycled gutters:

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The next post will focus on the parks of Funchal – there are over 30 “Jardim”, 2 vast”Parques” and a few “Quinta” (large estates surrounded by gardens), so plenty to entertain you with!

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From industrial site to contemporary garden

If you live in the UK, and/or like garden and plants in general, you can not have missed this week’s big event: the Royal Horticultural Society’s Chelsea Flower Show. Temple of gardening overindulgence, shrine to bizarre landscaping trends, and showcase of nurserymen’s skills, it’s also an inspiration for designers all over the planet, and this time I want to show you a real garden, near my hometown in France, ambiguously named the “Jardin des Traces“.

The Lorraine, region of North-Eastern France where I was born has a long tradition of steel industry, and landscape has always been dotted with tall blast furnaces. Many have closed and been demolished over the last decade, but one, the “U4″ has been preserved and become a listed building. To give you an idea, this is a view of the site in the 1970s, with the Moselle river on the right:

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The red lines show the site that has now become a 10-acre garden, divided into three themes. The first one is called “the alchemy garden“, and portrays the four elements needed to produce cast iron: earth (iron and coal), fire, water and air.

In the “earth” garden, rocks are represented by concrete walls encrusted with fossils, while soil fertility is suggested by the use of green walls and raised beds filled (not yet as it was a bit too early in the year!) with medicinal, edible or fiber plants:

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The “fire” is embodied by tall, flame-shaped metal sheets. There are burnt tree trunks painted in red, and acid-loving plants like maples (Acer palmatum) or Pieris; plus seasonal plants like red and yellow tulips.

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Sculptures have also been added to the garden, and I particularly love this one called the “Fire Doors”. Thanks to a switch in the doors, visitors can trigger a mister, forming a smoke-like cloud.

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The “water” garden is all transparency, with blue glass being used as mulching; and water is shown in all its states. Plantings are in shades of white and blue, with irises, geraniums or aquilegias, and grasses to display movement.

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Finally, the “air” garden uses bamboo hedges, with large wind chimes at the entrance, tall flowers swaying with the wind like Delphinium, and wicker globes hanging over the visitor’s head.

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The second part of the garden is dedicated to immigrant workers who came from all over Europe, from Poland to Italy or Algeria to help develop the industry in the region. Plants native to these countries have been used, such as the bladder senna (Colutea arborescens) which comes from the Mediterranean region:

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Parts and memories of the steel mill have been incorporated into the design, such as these giant valves:

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A few other examples include a little wagon used to carry ore or coal, and a warning sign that was found on pipelines transporting gas produced by the blast furnaces:

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The last part of the garden focuses on “energy“:  wind (with windmills), sun (with solar panels) and water (with japanese shishi-odoshi fountains).

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I hope you enjoyed the visit…I personally think that while it is a bit young (the garden only opened in 2009), it has been transformed into a peaceful yet thought-provoking place.

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I’ll let you have a look at the mind-boggling “pond with a hole”….

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A botanical walk with no frontiers

As some of you will know, I was born in North East France, very close to Luxembourg and Germany, in a region known as “The Land of the Three Borders“. Two years ago, I had introduced you to the orchid-rich nature reserve of Montenach.
This time, I visit a nearby hill with an interesting geological background….

The town of Sierck-les-Bains is located in a bend of the Moselle River (the V at the top of the maps).

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We start our walk at the top of the Altenberg, a hill made of shelly limestone (pale pink on the geological map). In a small woodland, I notice my 1st orchid of the season, Neottia ovata (Common Twayblade), sadly not yet in flower. Viburnum lantana (the Wayfaring Tree), a chalkland loving shrub, is flowering profusely along the path.

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The woodland quickly gives way to a plateau with large fields, many of which are filled with colza at the moment (bad for allergy sufferers, good for the photographer!). The chimneys in the distance are the cooling towers of Cattenom nuclear power plant.

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The paths and fields’ edge are filled with dry soil-loving plants such as the cypress spurge (Euphorbia cyparissias) or the chamomile (Matricaria recutita):

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The white bryony (Bryonia dioica), a toxic plant belonging to the gourd family enjoys the heat brought by rocks; and the (very) Common Field-speedwell (Veronica persica), forms little mats of blue flowers along the paths:

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Crop fields have always been associated with wildflowers, often annual plants which can withstand disturbance, drought, competition and complete their life cycle over a few months, sometimes less. Although they cause little disturbance to the crops, “arable weeds” have been deemed bad, and destroyed with large quantities of herbicides. It has been shown that they can actually have a positive role, providing shade and water retention for the crop, and attracting more pollinators to the fields.
Thankfully, the fields here don’t appear to be heavily sprayed, and we can still enjoy the pretty sightings of the Field Pansy (Viola arvensis), the Field Madder (Sherardia arvensis)…

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but also the Wild Mustard (Sinapis arvensis); and a very dainty but pretty mustard relative, the edible field pepperweed (Lepidium campestre):

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The walk then leads back into the forest with a steep descent:

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The flora here comprises many indicator species of ancient woodland (woodland that has suffered little disturbance for over a century, often much more), such as the Sweet Woodruff (Gallium odoratum), the Wood Sorrel (Oxalis acetosella) and a carpet of Dog’s Mercury (Mercurialis perennis):

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The banks of a little stream are home to the wonderful Yellow Archangel (Lamiastrum galeobdolon subsp. montanum) and the vigorous creeper Veronica montana (Wood Speedwell):

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Probably my favourites of all woodland plants, a large clump of Solomon’s seal (Polygonatum multiflorum) and the striking Herb Paris (Paris quadrifolia). Herb Paris normally has a whorl of four leaves under its flower (hence the name quadri-folia), but it can sometimes have one or two extra leaves, like here!

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The deeper we are descending into the valley, the shadier and wetter it gets. The path becomes a heaven for fern lovers:

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Among the ferns that can be found here are the Common Polypody (Polypodium vulgare); the Hart’s-tongue fern, Phyllitis scolopendrium, the Maidenhair spleenwort Asplenium trichomanes and a Dryopteris sp.

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As we start climbing back to the plateau, the edges of the path become drier again, and a different flora can be observed. Here’s the European columbine, Aquilegia vulgaris and a strange and uncommon umbellifer, the Sanicle (Sanicula europaea):

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The walk leads back to the fields of the Altenberg and….to a well deserved rest! :-)

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An oasis of wilderness

Green spaces are prized treasures in the brick and concrete jungle of cities. Yet, according to a report commissioned in 2013, London is the greenest city in Europe, with about 40% of its surface made of public green space:

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Of course most people will think of the large central green spaces such as Hyde Park, Hampstead Heath or Greenwich Park; but there are hundreds of smaller parks, garden squares, promenades or nature reserves to discover in the capital.

In South West London, very close to Morden tube station, Morden Hall Park is one of these. Originally land owned by Westminster Abbey, it was sold in 1553 to a rich family, the Garths, who enjoyed its tranquil settings far from the noises of the city. Sold again between 1800 and 1870s to a tobacco merchant, Gilliat Hatfield, the estate was given to the National Trust in the 1940s and now offers over 50 ha of park and wild land for all to enjoy (for free!):

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The Northern part of the estate has been left relatively wild and is occupied by wetland, which is just starting to green. One could easily forget that this is in London, a few hundred meters from a tube station, if it wasn’t for the distant noise of sirens!

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Many plants are already visible in this marshy land, such as the edible Water cress (Nasturtium officinale) and Ficaria verna (previously Ranunuculus ficaria), the Lesser Celandine:

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But insects too are coming back to life, like this brightly coloured leaf beetle (probably Altica sp.), here feeding on willowherb (Epilobium sp.):

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The River Wandle runs through the estate, and parts of its banks have been left wild, which makes a very relaxing promenade amidst the hustle and bustle of London:

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The shaded banks are covered in Cow Parsley‘s flowers (Anthriscus sylvestris), while a quiet part of the river hosts the nasty Floating Pennywort (Hydrocotyle ranunculoides). Originally from the South of the USA and Central America, it was imported to Europe in the mid 20th century as an ornamental pond plant, and has since become invasive in many countries. Pennywort is causing a lot of direct or indirect damages (loss of oxygen in water, flooding, pipe blocks…) but is very difficult to control. It is one of the five invasive aquatic plants whose sale has been banned by a government legislation starting April 2014, to try and limit their spread in the UK.

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In the late 1700s and 1800s, parts of Morden Hall Park were used an industrial estate. In particular, snuff (sniffing tobacco) production was well developed on the site, with two mills being used to grind the leaves. The mills are still visible today, and although the wheels are no longer functional (parts were removed during the wars to be used as scrap metal), it is still a very nice evidence of the industrial past of the place.

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Today, Morden Hall Park is a tranquil park only disturbed by bird songs and distant city noises, but I imagine what it must have been in the past with the mills running and many workers, suppliers, buyers and farmers around…
There is one noise though that you can hear nowadays: the buzzing of bees. Hives have been installed as part of a community project, with courses being given by a local Beekeeper’s association , and honey being sold to local residents.

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Who said life in London had to be all concrete? :)

 

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When plants glow

A fascinating and relatively unknown topic that I chose to study for my BSc, iridescence is, in its simplest definition, an “optical phenomenon in which hue changes according to the viewing angle”. The most obvious example is a soap bubble, but it is also a very common feature in the animal world (such as for this Morpho butterfly).

bubbleMorpho

What about plants?

In plants, iridescence takes three main forms: blue (e.g Selaginella wildenowii and S. uncinata, Begonia pavonina); green (e.g Phyllagathis) or pink/coppery (e.g Alocasia cuprea):

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You can discover other examples on the website of Patrick Blanc, the French and slightly eccentric botanist who popularised the concept of “green walls”: http://www.verticalgardenpatrickblanc.com/inspiration/leaf-colors

The phenomenon can be observed in most plant groups, but on a limited number of species. Interestingly, it has been mostly recorded in understorey plants of Asian forests, where the light level is only 1% of the light level in the canopy. This had led to the hypothesis that iridescence could be an adaptation to low light levels…but more about that later!

A brief history

Plant iridescence was first noticed (from what we know, I’m sure there must be accounts of shiny plants in early ages naturalists’ diaries) in 1896, by a German botanist named Ernst Stahl, who traveled extensively to Ceylon and Java. Studying Selaginella wildenowii, he observed “granules” of what could be a reflective pigment in the cuticle.

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Then, in 1971, Denis L. Fox and James R. Wells observe that iridescence in Selaginella disappears if the leaf is allowed to wilt or if the leaf is wet – because small airspaces on the leaf surface get filled with water. They emit the hypothesis that iridescence is (at least in Selaginella) an optical phenomenon.

In 1975, a study by Malaysian researcher David W Lee finds no iridescent pigments in the leaves of Selaginella, which confirms the hypothesis of an optical cause to iridescence.

How is iridescence possible?

I’m afraid I have to go into some physics now (but hey, who said botany was easy? :-) ). Normal leaves appear green because they reflect mostly green light. Blue leaves will appear blue because they will reflect mostly blue light. But how is that possible?

The mechanism behind this is called thin-film interference. Imagine the blue layer is a leaf, with A and B two rays of light. Ray A is reflected on the bottom surface, ray B on the top surface. The light that gets “reflected” will be a mix of ray A and B. If the two rays have similarly shaped curves (their wavelengths are “in phase”), they will add up and produce a very intense reflection (constructive interference). On the other hand, if the rays have opposite curves, they will cancel each other and produce almost no reflection (destructive interference).

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How the rays are reflected and at which angle depends on the thickness and density of the blue layer (air being very different to oil for example!).

How do plants produce iridescence?

Plants use various mechanisms to play with these factors. For example, if you look at these microscope pictures of Selaginella leaves, you’ll see blue leaves have bizarre layers in the cuticle (waxy surface of leaf), which act as light filters!

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Other plants have reflective layers in their chloroplasts (tiny structures found in plant cells which contain chlorophyll pigments), like the South American fern Trichomanes elegans:

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Why do plants “glow”?

Let’s have a look at this graph showing light reflected by Selaginella leaves (dashed lines are for green leaves, solid lines for blue leaves):

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The graph shows that blue leaves reflect a lot more blue light (around 415 nm), a lot less green light (around 550 nm) and around the same amount of red light. If you’ve had even just one course on photosynthesis, you’ve probably learned that red and blue are the best lights to make chlorophyll happy. So why would plants living in shade go without efficient, blue light??
Many hypotheses have been made, but none has been confirmed to date. Here are a few:

1) A sacrifice of blue light to increase photosynthesis?

According to this hypothesis, iridescent plants would “sacrifice” blue light to be able to capture more red light. However, if you look at the graph above, this is clearly not the case. Moreover, blue light is as important to photosynthesis as is red light.

2) A defence against herbivores

The idea is that iridescence could confuse herbivores, or make leaves look like non-food, unrecognised targets in a “scarecrow effect“. This would offer them a competitive advantage over other shade plants, in spite of their limited photosynthesis ability. The only observation of this has been made in an iridescent algae, Mazzaella flaccida.

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3) A protective mechanism

Most iridescent plants are adapted to live in deep shade. If such plant is placed into a high light environment, photoinhibition will occur, damaging chloroplasts, and sometimes leading to wilting. Iridescence would protect plants from damage in case of accidental exposure to high UV light, for example in case of a tree fall.

4) No role at all?

An interesting possibility. However, notes on cultivation of some species show that iridescence tends to disappear or be attenuated if the plant is grown in a less shady environment. This strongly suggests that iridescence has an adaptive role in plants!

I hope you enjoyed this little introduction to the strange world of plant iridescence…I’ll let you admire the iconic “Peacock Begonia” from Malaysia…

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And think about this quote from David Lee’s 1977 article: what if iridescent plants had a role to play in the future of mankind?!

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Paper, paste, plants and patience

A mysterious title for a not so mysterious activity…about a month ago, I took part in an Herbarium Workshop organised by the South London Botanical Institute (SLBI). While I had realised an herbarium before (including one for my BSc with 100 plants, all painfully sewed to thick paper sheets), I had never had the chance to see how “pros” do it. This was an unique opportunity to discover the tricks of the trade, as the workshop was given by two herbarium experts from Kew Gardens:

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Experts in action!

Hosted in a typical Victorian town house in South East London, the SLBI was founded in 1910 by keen botanist Allan Octavian Hume after years of serving in India, and has since been a place for botanists of all ages and interests to share their knowledge. The herbarium is home to over 100000 specimens of flowering plants, mosses or liverworts, mostly collected in the 1800s (though new ones are still added) and is stored in strange bespoke-made black iron boxes.

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Some interesting horsetail specimens (right pic is a specimen of Equisetum arvense, the Field Horsetail, collected in 1903 in Yorkshire), and old metal boxes used to safely collect plants in the field:

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But off with the visit, it was time to get to work! The protocol used for mounting was designed by W. H. Griffin, botanical assistant to Hume, and is similar to the one used at Kew. It is very much a question of personal/regional/historical preferences: all the specimens I worked on at the National Botanical Garden of Belgium were affixed to the sheets with gummed strips, but some institutions prefers to glue specimens as it prevents degradation if the sheets are frequently handled. The glue is water-soluble, so it can easily be removed:

Glued (left) and strips (right)  specimens of Leycesteria formosa

Glued (left) and strips (right) specimens of Leycesteria formosa

The protocol in itself is long (e-mail me if you want more detail, or try to attend another SLBI workshop :) ) but here are the basic steps:

1) Place label(s) on the sheet and carefully position your specimen so that it looks nice and that useful identifying features (for example leaf underside) can easily be seen.
2) Make small pencil marks to remember the position and remove everything from the sheet.
3) Put your specimen back on newspaper (preferably choose a page of no interest to you, so you won’t be distracted!), side-to-be-glued up, and start applying glue, with bottle, pencil or brushes.

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Applying glue…in a slightly messy way

4) Once everything is glued, turn the specimen on the newspaper, and press – this will remove the excess of glue and spread it out.
5) Lift the plant and place it on the sheet (remember those pencil marks you did earlier!), use little weights to hold it in place.
6) Using a wet sponge, dab the whole plant (particularly sides of the leaves and of the stem) to remove any excess glue.

All the material you need on this picture!

All the material you need is on this picture!

7) Glue the labels, place wax paper and put specimens under sand bag for drying…

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Finished work…well, almost

Et voilà…My specimen of Lythrum salicaria (Purple loosestrife) doesn’t look too bad, does it?

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That looks better, doesn’t it?

If you think this was complicated, well, have a look at this stunning specimen of Stachys sylvatica made by Griffin, where you can see all the stages of development. Specimen or work of art, one can wonder!

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A plant timeline

The SLBI organises workshops, lectures, surveys and plant fairs all year long, and I’m really looking forward to attending more fun events there. Just in case you get bored with the herbarium, there’s also a library full of interesting books, a nice glasshouse and a garden with medicinal and Australasian borders…

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A glasshouse full of wonders

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