Olive flower inflorescence

The Olive tree´s flower structure (inflorescence) is an interesting example that illustrates the striking similarity between the branch structure and the inflorescence structure.  Just like the arrangement of the leaves on the branch the flower structure is a branched "raceme" panicle that is both opposite an decusatte.  There is one central peduncle (main supporting stalk of the inflorescenc) from which secondary peduncles branch out in opposite (two from each bract in opposing directions) and decusatte (each set of opposite secondary stalks are offset 90 degrees the the ones before and after on the main peduncle.  Furthermore some of these secondary stalks are also branched opposite and decusatte with the pedicels (stalk of the flower itself).  If this all sounds a bit confusing then just observe the images in this post and you will be able to see the similarity between the branch structure (bottom picture) and the flower structure.

Olive branch leaf arrangement

 The Olive tree (species name: Olea europaea) has a leaf arrangement that is a good example of the "Opposite & Decusatte" arrangement.  The "opposite" part refers to the leaves arranged in pairs that grow out of the opposite sides of the stem.  The "decussate" part means that the leaves are arranged on a stem in opposite pairs at right angles to those above or below.  The images below give a pretty good perspective on what this looks like.  In the case of the Olive tree the leaves themselves have a narrow lanceolate shape with a short petiole.  These pictures also show the new inflorescence forming right above the petiole on the new branch growth.

Spanish Olive Oil

Spain is the world´s top producer and exporter of Olive Oil with about 45% of the global market.  This comes to about 1,400 Metric tonnes of Olive Oil per year, a figure that has increased quite a bit in the last ten years.  Among the countries that Spain exports to is Italy which is a bit strange considering that it is also an Olive Oil producing and exporting country.  The reason, I believe, is that Italy does not produce enough to meet its exportation demand and has to import Spanish Olive Oil which is then packaged in Italy and exported.  Italy produces about half the quantity of Olive Oil as Spain but in many areas of the United States at least is more well known.

"Interprofesional del aceite de oliva"  is a non-profit org. that is focused on promoting the use of Spanish olive oil.

The following is a list of Spanish Olive oil varieties, where they are grown and their characteristics..

• ARBEQUINA - originally from Arbeca, Lérida but now is grown in Cataluña, Zaragoza, Teruel and Huesca. This variety makes a high quality grade of oil.
• CORNICABRA - grown in Castilla.  This variety is very resistant to cold weather and to droughts. Its oil is known for a fruity, aromatic flavor and low bitterness.
• FARGA - grown in Tarragona, Valencia, Castellón and Teruel.  This variety is known for high level of oil production, a good quality oil although with a difficult extraction.
• MORRUT - grown in Tarragona and Castellón. This variety is not very high quality and is not known for regular or high levels of oil production.
• PICUAL - grown in the province of Jaén, this is the most important variety of Olive in Spain.  It accounts for about 50% of all Olive trees in Spain. Known for high level of oil production with a good quality product.
• PICUDO - grown in Cordoba, Jaén, Granada and Málaga.  This variety is emblematic of Cordoba.  Its production is varied from year to year but tends to have a high productivity.  It is prized for its unique characteristics.
• VERDIAL DE BADAJOZ - grown in Badajoz, Extremadura.  A medium production level that is variable from year to year.  The oil is quite fruity with a fairly strong bitter taste.
• CORNEZUELO - grown in the middle of the Iberian peninsula, most notably in the region of Toledo.  Constant level of production but not too high.  Known as quality, light oil. This variety is also used to produce table olives.
• HOJIBLANCA - grown in the Andalucian provinces of Sevilla, Córdoba and Málaga.  Accounts for 16% of the Olive trees in Andalucia.  The olives of this variety weigh from 1.5-4 grams and have about  22% production rate. This variety is also used to produce table olives.
• NEGRAL - grown in Aragón, Navarra and Jaén.  Along the banks of the Ebro river this olive variety occupies 50% of the fertile land.  Has a high level of production of high quality oil.  This variety is also used to produce table olives.

How many species of Olive trees are there?

Have you ever wondered how many species of Olive trees there are in the world? It is a natural question to ask given the wide variety of Olives that can be purchased at the grocery store. Well, the answer is ONE. There is just one species of Olive tree "Olea Europaea".

One common assumption is that black olives grow on one species of Olive tree and green olives grow on another species of Olive tree. This, however, is a misunderstanding of the difference between black and green olives. The difference in color is a result of when they are harvested and in fact all olives will eventually turn a dark red/purple or almost black color if left to full ripen on the tree. Green olives are harvested once they have reached their maximum size but before they begin to turn dark purple. The best time to harvest is when the color begins to turn from a green color to a lighter green almost yellow color. Black olives are harvested after they have ripened when not only the outer skin is a dark color but also the fleshy "meat" layer between the skin and the pit but before the the olive looses its consistency and begins to shrivel.

Some varieties of olive trees can produce both good green or black olives depending on when the olives are harvested. It is more common however that any given variety produce either good black olives or good green olives. Also some olive tree varieties produce olives that are not suitable for either green or black "table" olives and are used only for the production of Olive Oil.

It is also important to know that neither green or black olives can be eaten when picked right off the tree. Both need to undergo some sort of treatment before they can be consumed safely.

Olive tree tuberculosis

Olive tree tuberculosis is a disease found on Olive trees in Spain that is caused by the bacteria Pseudomonas syringae. When this bacteria is introduced into a wound on the tree caused by hail, pruning or by the beating of the branches to harvest the Olives it results in the formation of a gall like formation that starts off round and light brown and then grows into an irregular wart shaped canker that ends up with a dark brown color and very hard.

There is no cure for Olive tree tuberculosis other than careful pruning with clean tools. Most often however the condition is not treated as it does limited harm to the tree. An infected tree can often continue producing for a number of years after becoming infected. The best prevention seems to be to use clean tools to avoid spreading the bacteria in the process of pruning and to try to avoid excessive damage to younger branches during harvest.

The dark objects in the tree below are not olives but rather cankers caused by the Pseudomonas syringae bacteria.

Olive branches on US seals and coins

The Olive branch has long been a symbol of peace. Incorporated into the Great Seal of the United States is an eagle holding an Olive branch in its right talon. The seal was designed shortly after the United States declared its independence from England in 1776. The seal symbolizes both power and peace. The basic design of the seal has been incorporated into the seal of the President (with a few modifications), the seal of the Supreme Court, the seal of the Senate and many more.

Olive branches are also common on coins.

The lady "Liberty" is found on many coins and in some of them she is holding an Olive branch. The image above is the "Standing Liberty Quarter".

The Kennedy Half Dollar has the Seal of the President on its reverse side with the eagle holding the Olive branch.

Department of Defense seal is similar to the commemoration seal above. " Below the eagle a wreath of laurel to dexter and olive to sinister...The laurel stands for honors received in combat defending the peace represented by the olive branch" ( in Latin sinister means 'on the left side' and dexter means 'on the right side'.)

The three tree species that are very common on United States seals and coins are the Olive, the Laurel and the Oak.

Olive tree

In Southern Spain, where I live, there are a lot of Olive trees. Especially in the provinces of Cordoba, Jaen and Granada. These Olive tree growing regions are the source of a large percentage of the world´s Olive Oil and Olives.
So to get pictures of Olive tree all I have to do is walk out the front door and look around. Most o these pictures were taken within five minutes walking of where I live. The image above is of the Olive flower (blossom).
Any given Olive tree can produce green or black olives depending on when they are harvested. When they are harvested before they turn black you get green olives. If they are harvested when they are fully ripe you get black olives.
There is only one Olive tree species (Olea Europaea) but there are quite a few sub-species that produce different varieties of Olives. Olive tree wood is also extensively used as a carving wood and also for small furniture. Below is the base of an old Olive tree.

Common name(s):  Olive tree,
Scientific name:  Olea europaea
Family:  Oleaceae – Olive family
Native range:  Mediterranean region
Type: Evergreen
Non-native distribution: widely cultivated worldwide. Notably in California, Australia, Southern Europe, North Africa, Middle East etc.
Average height: 15 - 45 feet (6-15m)  
Forest or habitat:  Original range unknown. No truly wild populations exist.
Wood density and quality:  slow growing, moderately hard wood, beautiful grain
Leaf shape: Lanceolate, slighly cuneate (tip more rounded than base)
Leaf arrangement:  Opposite and decussate
Leaf margin:  Entire, slightly undulate
Leaf venation:  Rachis (main vein) visible and pronounced but secondary pinnate veins difficult to distinguish.
Leaf stem:  Short petiole
Leaf surface:  Glabrous. Dark green topside, light green bottom side.
Inflorescence type:  Raceme. Opposite and decussate (30-50 flowers per raceme approx.)
Flower: Small, creamy white,
Pollinating agents: Wind
Fruit type and color: Drupe, green then ripens to dark brown - purple-black
Edible?:  Yes (fruit and associated oil)
Seed description:  0.5 - 1.0 cm in length, pointy on both ends, “football shape”
Seed dispersal mechanism:  birds,
Bark:  smooth and grey in young trees and new branches. rough and furrowed in older trees.
Traditional uses:  food, oil, carving wood
Commercial uses:  cosmetics, oils, soap, cabinet wood
invasiveness:  limited
Iconic or symbolic value:  Olive branch symbolises peace and / or victory.  In the story of Noah´s arc the dove brought back an Olive branch signifying hope and restoration.