Whats looking Good Now
Gunnera manicata
.jpg "Gunnera")
OK, this may not be looking good, but it always causes comment!
We often have curious visitors asking what we are doing with the Gunnera during autumn. The giant leaves collapse gently, and bury anything they fall on. We find it better, neater and tidier, to prune them down as soon as they start to die off, wait too long and the stems go mushy and it’s like trying to move stewed rhubarb.
The leaves are inverted over the massive buds, which acts as frost protection (although we have not had any sever winters now for many years) and it reduces the damage from our resident water fowl which like to perch on the buds. By spring it will all have rotted away.
We usually give them a good mulch of rotten manure, something we always have plenty of, to feed their great growth next year.
Autumn Grasses
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Around the zoo we have many areas planted up with various grasses. They are often just a pleasant green background during the summer, but they come into their own during autumn when the seed heads are ripe and usually a bright white, especially so on sunny days, and even better if you can see them backlit.
The picture shows Miscanthus sinensis, a very popular grass that is native to Japan, Korea, and China. There are very many selected cultivars, with different heights, growth habit, or flower colour. Almost all are attractive in autumn.
Other grasses with good seed head display you may see as you walk around are Stipa gigantea, Anemanthele lessoniana, Cortaderia richardii, Ampelodesmos mauritanicus, Calamagrostis x acutiflora ‘Karl Foerster’, Chionochloa conspicua, and Molinia caerulea.
Liquidambar styraciflua
The rich autumn leaf colour of deciduous trees is nearly over. These leaves are under our Liquidambar styraciflua. Often just called Liquidambar, which neatly describes the autumn leaf colours. Another common name is Sweet Gum, from the pleasantly scented resin in the leaves – just gently crush a leaf and smell.
Leaves turn colour in autumn as part of the natural process of the leaf dieing off. Each leaf stem forms an abscission layer next to the bark, a corky layer that stops water and food transfer to the leaf. As this happens the chlorophyll, which gives the leaf its green colour, breaks down. As the green pigment fades, orange, red and yellow pigments appear, from the carotenoids, anthocyanins, and xanthophylls within the leaf. Each plant has a different proportion of each, hence the range of colours. And the weather plays a part too, cold frosty weather always makes the process quicker, and the colours are more intense.
Giant Pineapple
Puya chilensis
All right, the common name is a bit of a cheat as this great plant is a member of the Pineapple Family, but does not produce any edible fruit. It does look like a pineapple plant though!
Puya come from high in the Andes of South America. They grow very slowly
- this plant is about 10 years old - and then flower in one year and die.
The very prickly leaves are a defence against browsing animals - if you grow slow you don't want to lose leaves do you?
The flower spike grows fast - about 250mm per week. The flowers spikes have sterile tips that act as perches for the Humming Bird pollinators so they rest between meals.
Pineapples are probably the best known family member - world production is about3.5million tons a year, most of it for juice. Other plants in the family give us fibre too.
You can find this plant just in front of our Discovery Centre. We'll update these pictures as the flower develops.
To expand the story, many Bromeliads (the scientific name for the family) are very useful for animal and insect life as they have a natural water reservoir in the centre of their leaves (some houseplants such as Aechmea show this well). These are used for drinking, frog rearing (individual eggs laid in each 'urn', and are also good places to hide during the day.
Euphorbia
Many people become quite euphoric about how great Euphorbia are, but some have phobias against them, enough of that!
We grow several different Euphorbia around the zoo, they are showy in flower, and often evergreen so give a good display all year. Our favourite species would be E. mellifera, from Madeira, with honey scented flowers (mellifera means honey bearing, the honey bee is scientifically Apis mellifera). The flower colour varies, ours are red, many peoples are green, and they often hybridise with other shrubby Euphorbia, causing even more variety and confusion. Just enjoy them!
Apart from the shrubby E. mellifera, we grow some herbaceous species such as E. myrsinites and E. characias. These grow new shoots each year from the base after last years shoots flower, all we need to do is carefully prune out the flowered shoots once flowering is finished, normally by summer.
The Euphorbia or Spurge Family is very large and diverse, with 300 genera of about 5000 species around the world, with the bulk of them found in the tropics. They range from small succulents to large trees. Many are familiar to us, or at least their products are – cassava, tung oil, vegetable tallow, and especially rubber of course. How man people have Poinsettia as a houseplant, or maybe a Croton? One other perhaps familiar product is the jumping bean. This is the seed of Sebastiana pringlei, with the larvae of a moth Carpocapsa saltitans inside it. If exposed to heat, say warm sunlight, the larvae ‘jumps’ in the bean, hoping to jump somewhere less warm.
Many Euphorbia have a white latex, which is very copiously produced in Hevea, the Rubber Tree, but its main purpose is to deter insects and animals from browsing on the leaves and stems – great for us gardening in a zoo as no animals go near them. Gardeners should be wary of the sap of garden species, wearing gloves and washing any sap off the skin quickly as it can be an irritant, and be very careful to keep it out of your eyes. One of the most poisonous chemicals we know (Ricin) is extracted from the seed of Euphorbia Family member Castor Oil (Ricinus communis).
Red Robin
Photinia x fraseri
Don’t those red leaves look lovely!
Well, that depends on your viewpoint! Many gardeners enjoy various brightly coloured leaves as part of their garden display – the picture shows Photinia x fraseri ‘Red Robin’, planted within our Kaziranga Forest Trail. Many different plants have red leaves, often only when young, turning green later. Gardeners have selected particularly good forms, and often spotted really unusual colour variations that look bright and attractive.
But why do the plants have red leaves? It’s actually quite simple. Almost all plants at some stage will suffer from animals or insects trying to eat them. This has two effects, it damages the plant, and it reduces the leaf area available for the plant to manufacture food. If a plant spends a lot of energy putting out new leaves only to have them eaten quickly, it suffers more as it has not had time to gain anything from the leaves.
So how do plants reduce this? Browsing and grazing animals or insects will normally look for the most tasty part of the plant. This is often the newest growth, it will be far more tender. Fresh leaves are normally bright green, old leaves often brown or red. So if the plant keeps young leaves red, they will be browsed much less as animals – and insects too – will largely ignore them.
The plant produces various flavonoids and anthocyanins, chemical compounds, for various reasons, which also give the leaf it’s red colour. Flavonoids are very good at limiting fungal and insect attack, but are often useful to animals as disease inhibitors – many herbal medicines are in fact based on the flavonoids within the plant. Anthocyanins are far more toxic normally.
Photinia x fraseri ‘Red Robin’ is a garden hybrid, a cross between 2 species (P. glabra from Japan and P. serratifolia from China) selected for it’s particularly good red leaf colour. This fades with the summer, but it also has on older plants a good show of white flowers in spring.
Silver Wattle
Acacia dealbata
Native to South East Australia and Tasmania. Introduced to Europe in 1820.
Acacia belongs to the Pea Family Leguminosae. All members of this Family, which includes Clover, have a symbioitic relationship with bacteria that produce nitrogen in their roots. The plant feeds the bacteria sugars, and the bacteria feed the plant nitrogen, which boosts growth.
Australia has the poorest soil on earth (it’s the oldest continent) and Acacia have evolved to grow in poor soil. Plant it in Ireland, with excellent soil, plenty of water, and good mulches from the garden team, and it grows too quick, often falling over, and never with a long life – say 10 – 15 years maximum.
Picture taken near the underpass, but several specimens around the Zoo. We also have a few different species, A. baileyana, A. longifolia, A. riceana, A. pravissima, and A. paradoxa in various areas.
Honey Spurge
Euphorbia mellifera
We have this plant in many areas around the zoo, it even seeds itself gently around. They flower from early March, the dark red flowers making a good contrast to the evergreen leaves. The epithet ‘mellifera’ means ‘honey bearing’ – the flowers are rich in nectar with a strong honey scent.
Native to Madeira and the Canary Islands, it is a component of the laurosilva forests, which used to cover a lot of the land there, but not any more. In the wild it can grow to 20m, but in Ireland the biggest I’ve seen is about 3m.
All Euphorbias have a milky sap, which can be an irritant if in contact with eyes or skin on some people. The sap is obviously a great deterrent to any insect or animal grazers, the majority of Euphorbia are found in tropical areas, and often in dry areas, where green plant growth would be highly valued.
The common house plant Poinsettia is Euphorbia pulcherrima, and there are several too common annual garden weeds in the same family.
Honeybush
Melianthus major
Originally from South Africa, introduced to Europe about 1688. The Melianthaceae Family is only found in Southern Africa.
Called Honey Bush as the nectar drips from each flower – very easily seen as it is black! Look closely and you’ll see drops on the new flowers – taste it too, I’m still alive and kicking afterwards.
You can see these superb architectural plants in various places around the, but especially in the staff car park and opposite the penguins/sealions/snowy owls.
They thrive in dry conditions, needing little attention bar the odd bit of dead heading, and perhaps pruning down of some old stems every other year to keep neater.