What are the morphological characteristics of pine trees? The latest detailed explanation is here

Pine trees are the collective term for plants in the genus Pinus of the family Pinaceae. There are nearly over eighty species in the world. They are extremely adaptable to terrestrial environments, able to tolerate low temperatures of -60°C or high temperatures of 50°C, and can grow in bare mineral soils, sandy soils, volcanic ash, calcareous soils, limestone soils, and various soils ranging from podzolic soil to red soil. They are famous pioneer tree species. Now let us take a look at the morphological characteristics of pine trees!

Trunk

After maturity, a pine tree reaches up to 45 m tall with a diameter at breast height of 1.5 m. The bark is reddish-brown, grayish-brown on the lower part, and splits into irregular scaly blocks. The branches spread horizontally or slantingly. The crown is broadly tower-shaped or umbrella-shaped. The branches grow one whorl per year, but in southern Guangdong they usually grow two whorls per year. They are pale yellowish-brown, without white powder, rarely with white powder, and hairless. The winter buds are ovoid-cylindrical or cylindrical, brown, pointed at the apex. The edges of the bud scales are filamentous, with the apex pointed or forming an acuminate long tip, slightly recurved.

Leaves

The scale leaves of pine trees are solitary, linear and green when young, then gradually degenerate into brown, membranous bract-like structures, from whose axils the needle leaves (secondary leaves) emerge. The needle leaves are 2 per bundle, rarely 3 per bundle, 12-20 cm long, slender and soft, slightly twisted, with stomatal lines on both sides and fine serrations along the edges. They grow on undeveloped short shoots, and the base of each needle leaf bundle is surrounded by a membranous leaf sheath. The leaf sheath is initially brown, then gradually turns grayish-black, and persists.

Flowers

Pine trees are monoecious, with unisexual cone flowers. The male cone flowers are solitary in the bract axils of the lower part of new branches, mostly clustered. The stamens are numerous, with 2 anthers, and the anther cells split longitudinally. The pollen has two well-developed air sacs; the contact surface between the air sacs and the body is relatively small with a clear boundary, and they generally all have a prominent marginal rim. The female cone flowers number 1-4 and are borne near the apex of new branches. They have numerous ovuliferous scales and bract scales. On the ventral base of each ovuliferous scale, two inverted ovules are borne. Pollination occurs in the same year, and in the second year they rapidly enlarge into cones.

Cones

Some species of pine trees bear fruit relatively early, producing a small amount of seed in 5-6 years, with a marked increase at 15-20 years. Some species bear fruit very late; for example, the Korean pine under natural forest conditions does not begin to bear fruit until 80-140 years. The cones mature in 2 years. When ripe, the seed scales open, rarely remaining closed. They are ovoid, long-ovoid, nearly round, or cylindrical, upright or pendulous. The seed scales are woody and persistent. The exposed upper part is usually thickened into an apophysis, with or without a distinct transverse ridge. The apex or center of the apophysis mostly has a raised or slightly sunken umbo, with or without a prickle. The fertile seed scales bear 2 seeds. The seeds have an upper wing, and the cotyledons number 3-18 and emerge above ground upon germination.