Trees On Stamps :

Young rubber trees (Hevea brasiliensis) in a plantation are depicted on the 40c value (Sc #323) of Ceylon's 1954 Local Scenes definitive series.

From srilankabusiness.com, "Started in 1876, with the planting of 1,919 rubber seedlings, ...Sri Lankan natural rubber has since acquired the status of an industrial raw material with a global significance."

Here is the 2d value (Sc #198) from Sierra Leone's January 2, 1956 QEII pictorial definitive series. Stamp depicts a large tree and is inscribed "The Cotton Tree, Freetown".

From wikipedia, "The cotton tree (Ceiba pentandra), also known as the kapok tree, is an historic symbol of Freetown, the capital city of Sierra Leone. According to legend, the 'Cotton Tree' gained importance in 1792 when a group of former African American slaves, who had gained their independence by fighting for the British during the American War of Independence, settled the site of modern Freetown. These Black Loyalist settlers, called 'Nova Scotians' because they came from Nova Scotia after leaving the United States and before they decided to go back to Africa or 'Navatians' in Sierra Leone, founded Freetown on March 11th 1792."

The giant cotton tree was there when the settlers landed, and it is still there today.

Syria
28th September 1970
World Year of Olive-oil Production

The 2 centesimo value (Sc #607) of Uruguay's January 14, 1954 National Images definitive series of 17 stamps, depicts the ombu tree.

From wikipedia, "Phytolacca dioica is a massive deciduous tree native to the Pampa of South America. It has an umbrella-like canopy that spreads to a diameter of 12-15 meters and can attain a height of 12-18 meters...It is a symbol of Uruguay and Argentina, and of gaucho culture."

Tall palm trees dominate this high contrast image of Cobija City, Bolivia. The 28 bolivianos stamp (Sc #672) was issued on July 8, 1982 to commemorate the 75th anniversary of the city's founding. Cobija City is located in the northeast of the country, in the Amazon Basin near Brazil.

Tunisia
Ficus macrophylla
November 24, 2020
The souvenir sheet and stamp features an 130-year old fig tree Ficus macrophylla at Belvedere Park in Tunis.

On September 7, 1962 Peru issued this 1 sol stamp (Sc #482) to commemorate the centenary of the founding of the Province of Pomabamba. Stamp depicts a huge, double-trunk tree (the "Centennial Cedar") in the market square of the town of Pomabamba.

The 20c value (Sc #580) from El Salvador's 1938-9 pictorial series shows workers in tall trees "extracting balsam".

From wikipedia, " Balsam of Peru, also known and marketed by many other names, is a balsam (resin) derived from a tree known as Myroxylon balsamum var. pereiras. it is found in El Salvador, where it is an endemic species. Balsam of Peru is used in food and drinks as flavoring, in perfumes and toiletries for fragrance, and in pharmaceutical items for healing properties. It can (commonly) cause allergic reactions."

This tree species has been introduced into Sri Lanka.

Malaysia
World's Tallest Tropical Tree
December 29, 2020
The minisheet depicts the Yellow Meranti tree (100.8 m tall) found in the Danum Valley, Sabah.

This 5 escudos stamp (Sc #321) of Mozambique is from the "Landscapes" series of 1948. It depicts copra-harvesting workers at one of the country's coconut palm (Cocos nucifera) farms.

From news.trust.org, "In 2011 Mozambique produced approximately 62,000 tons of copra, which was used for export, oil production, and local consumption. Today, reports estimate that as much as half off the country's coconut trees have been destroyed. The disease (Coconut Lethal Yellowing Disease) which has been found across the world is caused by a virus-like bacterium that is spread by insects."

On May 12, 1969 Finland issued this set of three anti-tuberculosis, semi-postal stamps (Facit #s 661-3) featuring native trees.

.20 + .03 mk juniper (Juniperus communis)
.25 + .04 mk aspen (Populus tremula)
.40 + .07 mk. bird-cherry (Prunus padus)

"Close ups"/details of evergreen trees are depicted on Finland's August 8, 1995 special booklet stamps (Facit #s 1305-8) commemorating the 20th World Congress of IUFRO (International Union of Forest Research Organizations). Meeting was held in Tammerfors, Finland on August 6-12, 1995.

#1305 silver birch (Betula pendular)
#1306 Scotch pine (Pinas sylvestris)
#1307 Norway spruce (Picea abies)
#1308 development of a pine tree from a cutting

On October 21, 2010 the USA issued a booklet of 20, domestic letter rate "forever" (44c at time of issue) stamps (Sc #s 4478-81). Stamps are themed "Holiday Evergreens", meaning that in the USA these are the most utilized evergreens for Christmas trees. The stamp on the right in the first scan is commonly called eastern red cedar, but actually it is a juniper.

Sc #4478 ponderosa pine (Pinus ponderosa)
Sc #4479 eastern red cedar (Juniperus virginiana)
SC #4480 balsam fir (Abies balsamea)
SC #4481 blue spruce (Picea pungens)

Here is Lithuania's March 20, 2010, 1.35 litas Easter stamp (Sc #914).

On July 1, 1950 North Borneo issued this 3c value (Sc #246/SG #358) as a part of the KGVI pictorial definitive series of 1950-2. A grove of coconut palm trees is depicted.