Trees On Stamps :

Cyprus
Centennial Trees in Cyprus
March 28, 2019
0.34€: Oriental Plane (Platanus orientalis)
0.41€: Mediterranean cypress (Cupressus sempervirens)
0.64€: Mount Atlas Mastic Tree (Pistacia atlantica)

Here is Iceland's July 18, 1984, 1000 aur stamp (Facit #655) commemorating the centenary of the International Order of Good Templars, a temperance organization. Stamp depict's the organization's original lodge in Akureyri.

On September 4, 1957 Iceland issued this set of two stamps (Facit #354-5) promoting reforestation. The 35 aur value shows an evergreen tree before volcanoes, and the 70 aur stamp depicts a large birch tree and smaller evergreens.

Uruguay
International Year of the Forest
September 21, 2011
The stamp depicts Espinillo (Acacia caven), an ornamental tree in the family Fabaceae.

A birch sapling is shown on this November 19, 1975 stamp (Facit #549) of Iceland promoting reforestation.

On September 23, 1965 Finland issued this .35 mk stamp (Facit #611) to commemorate the birth centenary of Finnish painter Pekka Halonen (1865-1933). Stamp depicts Halonen's painting Winter Day (1899).

This 5 shilling stamp (Sc #127) from Jamaica's KG VI 1938-52 pictorial definitive series depicts what appears to be a wood sprite by a stream on a starry night. The inscription reading "isle of wood and water" refers to the name for the island (Jamaica) used by its pre-Columbian Yamaye inhabitants.

From wikipedia, "The indigenous people, the Yamaye (also known as the Taino) called the island Xaymaca in an Arawkan language, meaning 'Land of Wood and Water' or the 'Land of Springs'."

Israel
Trees of Israel
December 4, 2018
The stamp set depicts Strawberry Tree, Mount Tabor Oak, Judas Tree.

India issued a set of two stamps (2 As. and 14 As.) on 24th May 1956 to mark the 2500th Birth Anniversary of BUDDHA. Both the stamps depict the famous BODHI TREE in stylish graphics.

India issued a 25 Paise stamp on 27th December 1976 to mark the Diamond Jubilee of Coconut Research. The stamp depicts a Hybrid Coconut Tree.

India
Conservation of Forests
15 June 1981
Stylized Trees

In 1993 Seychelles issued a Flora and Fauna definitive series of 14 stamps depicting native plants and animals. The one rupee value (Sc #742) of the series shows Seychelles splendid palm (Verschaffeltia splendida).

From wikipedia, "Verschaffeltia splendida...is the only species of the genus Verschaffeltia. It is found only in Seychelles where it is threatened by habitat loss."

From 1938-41 Seychelles issued a set of 24 values for its KGVI pictorial series. Three different were used for these stamps, one of which is the coco de mer palm, which is native two of the Seychelles's islands. Two of these stamps, the 50c and 1.50 rupees values (SC #s 141 and 146) are shown here. The identical tree image was used on the two successive definitive series, the KGVI 1952 set and the QEII 1954 set.

From amusingplanet.com, "In the islands of Praslin and Curieuse, in the Seychelles, grows one of the most elusive palm trees in the world. The coco de mer (Lodoicea maldivica) has tall, slender trunks that rise more than 30 meters above ground...Possibly the most renowned feature of of coco de mer are its enormous seeds - the largest and heaviest in the plant world...The seeds bear an uncanny resemblance to a woman's (rear end)."

The complete story is more interesting, IMO, but this is a family friendly site, and I dare not say more. Readers are warned that if they are offended by acorns, butterbeans, or palm seeds they should not search for the whole story.

India
Ficus Benghalensis
19 November 1987
Banyan Tree

The $1 value (SG #352) of Trinidad and Tobago's 1969 definitive series depicts a yellow poui tree (Tabebula serratifolia) ib bloom. The trees bloom each year from January to May, marking the end of the dry season.