Euphorbia pulcherrima (Poinsettia)

The plant that is most commonly associated with Christmas is the poinsettia.  You can certainly see a large number of large poinsettia plants decorating areas of RBG centre, especially around the train displays and forming a large, impressive tree in the bulb room. In fact there are over 500 plants in the building.

The Poinsettia tree in the bulb room.

Dr. Joel Poinsett

The poinsettia is a member of the spurge or Euphorbia genus, with the species name pulcherrima, meaning 'most beautiful' (Euphorbia pulcherrima). It is native to southern Mexico and Guatemala, gaining its common name from Dr. Joel Roberts Poinsett. Poinsett was an amateur botanist and the first U.S. Ambassador to Mexico in 1820’s, discovering the poinsettia in wilderness of the Taxco area.  He sent some of these plants back to cultivate in his greenhouses in South Carolina, distributing them to friends and botanical gardens. Originally they were known to people as ‘Mexican fire plant” or “painted leaf” but eventually the name Poinsettia gained popularity, recognizing Poinsett’s role in introducing the plant to America.

An old Mexican legend describes the association of poinsettias with Christmas. A poor Mexican girl wanted to give baby Jesus a present at the Christmas eve services, but not being able to afford anything picked a handful of weeds from the roadside. Once laid at the base of the nativity scene the weeds burst into bright red flowers. In Mexico they are known as Flores de Noche Buena (Spanish for "flowers of the holy night").

Red is the most popular colour making up more than
half of the Poinsettia sales, followed by white and pink.

Poinsettia’s can come in a variety of colours such as the popular flaming red, orange, pale green, cream, pink, white or marbled.  They can range in size up to that of a small tree 4 metres high.  

A 12 foot tall Poinsettia in Florida

A gangly natural Poinsettia grown in
the tropics.

The red coloured structure is not the actual flower, but rather they are bracts, or modified leaves. At the centre of ring of bracts is a cluster of green and yellow structures called cyathia.  Each cyathium is an inflorescence, or flower cluster, comprised of many individual male flowers, and a single female flower.

The ring of bracts can be seen extending out from below
the green and yellow cyathia.
 Each cyathium contains an immature cluster of
male flowers with one single female in the middle.

The male flowers are more mature and pollen
can be seen on the stamens.
Poinsettia will last longer if bought when the
cyathia are not developed and resemble 
little peas.

Each cyathium bears a two-lipped, yellow gland
that produces nectar to attract insects.

The bracts of the Poinsettia are originally green
and gain colour as the plant matures.

Poinsettias (Euphorbia pulcherrima) can be identified as members of the Euphorbiaceae family because they release a milky sap, containing latex, when leaves or branches are broken. Some people may develop skin irritation from direct exposure to the milky sap. However it is not poisonous.

Here you can see the milky
sap being released at the points
where the bracts were removed.

The American Sycamore (Platanus occidentalis)

Peter Langballe led the Sunday walk,
while Mary Lyn Brown and Renata were two of
those who joined in.

A great way to spend a couple of hours on a Sunday afternoon is to go on one of RBG’s guided Back to Nature Walks led by an Auxiliary member.  Late fall provides different views along the trails due to the absence of foliage that normally limits how far one can see the wooded landscape.  There is still much to see, too much to describe here.  

One of several sycamore trees seen on
the trail.

One of the plants of visual  interest is the Sycamore tree (Platanus occidentalis) also known as the American sycamore, American plane tree or buttonwood, native to eastern North America. There are several of these trees along the shores of South Pasture Swamp with the large size, the bark and the fruit all catching your attention.  

The peeling bark produces the "camouflage" pattern

The bark peels off in irregular strips, leaving behind splotches of brown or gray, producing a camouflage effect.  From a distance across the swamp the towering trees stand out due to their white colour. These trees commonly inhabit wet areas. At up to fifteen feet in diameter, the sycamore develops the broadest trunk of any native tree. In fact the genus name is derived from “platy” which is Greek for “broad”.

The white sycamores are readily visible in the background.

The fruit provides great winter interest. This fruit forms brown seed balls, about one inch in diameter, which remain hanging from the tree singly attached by a long stalk.  Inside the fruit is a tightly packed cluster of “achenes” which are small, dry, one-seeded fruits that do not split at maturity, each one sporting a hairy tuft to help with dispersal, much like the dandelion. The name ‘buttonwood’ for the sycamore is due to these fruits which may stay on the tree throughout the winter, breaking apart in the wind to disperse the seeds.

The brown seed balls of the fruit.

A close up view of the seed ball.

The inside of the seed ball.

Leaf from the sycamore tree

The leaf of the tree is much like a maple leaf.  In fact Platanus acerifolia, commonly known as the London plane tree, is a hybrid resulting from the cross of Platanus occidentalis and Platanus orientalis.  It is often used in urban plantings in place of the American sycamore due to its high tolerance to pollution and its production of shade.  One way to distinguish it from the native sycamore is that the fruit balls hang in pairs. 

Note the alternate attachment
of the leaves

It has been stated that the maple leaf found on the Canadian penny is actually from this tree.  Although the sycamore leaf and maple leaf are similar, maple leaves grow ‘opposite’ on the branch while the sycamore has an ‘alternate’ arrangement.  

There is so much more information to be found about the sycamore tree.  Have a look at the following web site: http://ontariotrees.com/main/species.php?id=2083

The Pinetum

The Pinetum is an area in the Arboretum often overlooked by visitors to RBG. Unlike the name “Pinetum” seems to imply, pines are not the only variety of trees to be found in this area.  Instead, there is a collection of a variety of conifers that has seen significant additions this past year. The pine family (Pinaceae) being the largest conifer family is rightly well represented with many specimens from the largest genera of Pinus (pines), Abies (true firs) and Picea (spruce) as well as the less populated genera of larches, hemlocks and Douglas fir.  There are also a large number of members of the cypress family (Cupressaceae) in the collection, namely the popular genus Juniperus (juni pers) along with many Chamaecyparis (false cypress) and the newer additions of Cryptomeria japonica (Japanese cedars) found at the entrance to the Pinetum Trail.

Douglas fir

There is so much that can be written about this collection, but in keeping with the approaching season, let’s look more closely at the pine, firs and spruce that are often used as Christmas trees and examine how they can be differentiated. 

If you would like to see the more popular Christmas tree choices have a look here:

http://www.realchristmastrees.org/dnn/Education/TreeVarieties.aspx

The best place to start conifer identification is to look at the needles, since pine needles are bundled with usually 2, 3 or 5 in a bundle while spruce and fir needles are found singly. Take a look at the chart below to see the major differences between these two. (For brevity cones and tree shape will not be dealt with in this article.)

Needle characteristics	Spruce (Picea)	Fir (Abies)
SHAPE	Four sided – will ‘roll’ between your fingers	Flat – will not roll
FEEL	Stiff, sharply pointed	Softer than spruce
LENGTH	No consistent differences
ARRANGEMENT ON THE BRANCH	In spirals around the branch giving it a three dimensional look.	The branch has a flattened appearance
WOOD ON BRANCHES	Needles are attached to woody projections, so branch is rough after needles fall	Branch is smooth after needles fall with a scar left by the needle

A spruce with four sided needles.
Needles are attached singly and spiral
around the branch.

A fir with flat needles.
Needles are attached singly and tend to spread
to the sides to give a flattened appearance to the branch.

A pine branch

There are up to 100 species of pines, however the most common Ontario species can be differentiated by examining the needles.  The Eastern White Pine has long needles in bunches of 5, while the Red Pine has long needles in bunches of 2.  Pitch pine needles occur in threes.  Scots Pine and Jack Pine both have shorter needles in twos, but the Scots Pine needles are twisted, while those of Jack Pine are not.

White pine with needles in groups of five

Red pine with needles in groups of two

Jack pine - needles are in twos, but shorter than
the Red pine

To learn more about any of the genera of conifers, go to the web site for Ontario Trees & Shrubs and click on the genus name.  You can also use the list on the left of the page to change your search criteria.

http://ontariotrees.com/main/list_genus.php

 Flowering in the Med House this Week

Well, that cold spell and last week's snow fall certainly put an end to the few lingering blooms in our gardens. Although it's currently not peak bloom time in the Mediterranean Garden if you are suffering from withdrawal symptoms and need a "flower fix" then go have a stroll through RBG centre's green house.




Most resplendent right now is the Bougainvillea that drapes across the arbor above the stairs to the second level and is even seen poking through the aqueduct of the train display with a cluster of magenta blooms.

Pentas lanceolata 

There are many Pentas lanceolata (Star Cluster) plants and clumps of Osteospermum ecklonis (African Daisy)  scattered throughout the garden, brightening up the greenery with colours of pink, yellow, white and mauve. 

Osteospermum ecklonis

Reds seem to dominate at the moment with the prolific blooming of the Pelargonium acetosum (Sorrel Geranium), the tubular flowers of the Tecoma capensis (Cape Honeysuckle) and the delicate blooms of the Callistemon linearis (Narrow Leaved Bottlebrush) and Acacia farnesiana (Sweet Acacia) with it's brush type red flowers. 

Pelargonium acetosum (Sorrel Geranium)

Tecoma capensis (Cape Honeysuckle)

Callistemon linearis 
(Narrow-Leaved Bottlebrush)

Acacia farnesiana (Sweet Acacia)

Nandina domestica (sacred Chinese Bamboo)

 Another splash of red colour is provided by the large clusters of berries of the Nandina domestica (sacred Chinese Bamboo). This is not actually a bamboo, but an erect evergreen shrub. 


There are many more flowers around the Mediterranean Garden at the moment in varying colours of white, orange and yellow. Go have a look and see if you can spot them yourself. 




While you are at it be sure to wander through the Cactus and Succulent Collection. This is not a place you would normally expect to find flowering plants. However, the Euphorbia have a few specimens with blooms, including the red of the Euphorbia milii (Crown of Thorns), the yellow flowers growing above the spines of the Euphorbia grandicornis (Cow's Horn) and the less defined yellow flowers along the ridges of the Euphorbia ingens (Candelabra Tree).  Cacti can produce large stunning flowers, but expect to find those later.  Right now there are several small white flowers on the Mammillaria plumosa (Feather Cactus), while the Mammillaria prolifera (Texas Nipple Cactus) has just about finished flowering and is displaying the resulting red cylindrical fruit.

So give yourself a treat and take time to wander around the Med House on a regular basis.  In the coming months.It will certainly provide a cure for the winter blahs.

Euphorbia milii

Euphorbia grandicornis

Euphorbia grandicornis

Euphorbia ingens

Mammillaria prolifera

Mammillaria plumosa

Cucumeris

Have you noticed the white envelope type bags hanging from various plants around RBG centre and the Mediterranean Garden?  Did you wonder what was in them.

A good guess would be that the bags contain a type of biological pest control, a favourable alternative to chemical pesticide sprays. Various biological control agents can be used, with most belonging to one of the following categories: predators (eat the pest), pathogens (infect and kill the pest) and parasites (live on or in the pest, eventually killing it).  Much research is done to find appropriate beneficial agents to combat specific pest organisms.

Echinothrips americanus

These bags are tagged www.AppliedBio-nomics.com and stamped A. Cucumeris Slow Release, which makes it very easy to find out what they contain.  Amblyseius cucumeris is a species of predatory mite that feeds on a variety of thrips, the 2-spotted Spider mite as well as a few other species and whitefly eggs. Each bag contains about 30 mL of the predator, along with a food source.  The cucumeris will breed and over a four week span produce about 1000 offspring that will leave through a small hole and move about the plants to find food in the form of the targeted pests. Cucumeris adults are not readily visible since they are less than 0.5 mm long, pear-shaped and tan coloured.  The eggs are tiny, being 0.14 mm in diameter, round and transparent.

Amblyseius cucumeris

Have a look here to read more about cucumeris.  http://www.appliedbio-nomics.com/products/cucumeris/  Click on PRODUCTS at the top to see the other beneficial agents handled by this company.

If you are interested in more information on biological control there are many websites to visit, but an informative one is hosted by the University of California.

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74140.html

The Botanical Train Exhibit  

• If you have walked through RBG centre this past week, you can’t help but notice that the construction of the Holiday Traditions Train Display is almost done.
• This is the third year that the train display has been set up in McQuesten Theatre to be an integral part of RBG’s Christmas celebrations.
• This display is the product of Applied Imagination, a company that specializes in creating botanical train displays and it features several Canadian landmarks formed from natural materials.
• The garden-scale (G scale) trains are 1/29^th the size of life size trains.
• Although Applied Imagination set up the original exhibit, it was dismantled by RBG staff and a few Auxiliary volunteers.  Each year it is set back up by the staff, again with the help of volunteers.  Last year Auxiliary members added the pond skating scene and this year the figure 8 track has been replaced by a larger loop.
• The Wonders of the World train exhibit was installed in the Mediterranean Garden by Applied Imagination last year and this year RBG has set up a train track in Turner Pavilion, featuring Thomas the Tank engine to help entertain the children while they wait to see Santa.
• If you go to the following link you will see photos of the original setting up of the train exhibit by Applied Imaginations as well as photos of some of its features.

Set up of the exhibit in 2012

 http://appliedimaginationbiz.wordpress.com/category/royal-botanical-gardens/

• A visit to this page will show you some of the locations that feature installations of Applied Imagination trains including Botanic Gardens in New York and Washington D.C.  Scroll down the page to see the collections of photos.

              http://www.appliedimagination.biz/#welcome