The appearance characteristics of Pine trees

Pine is the general name of pine plants in the pine family. There are nearly 80 species in the world. They are highly adaptable to the terrestrial environment. They can withstand a low temperature of-60 ℃ or a high temperature of 50 ℃. They can grow in bare mineral soil, sand, volcanic ash, calcareous soil, limestone soil and various soils from podzolic soil to red soil. They are famous pioneer tree species. Let's take a look at the shape and characteristics of pine trees.

Dry

After maturity, the pine is up to 45 meters high, with a breast diameter of 1.5 meters, reddish brown bark, lower grayish brown, and split into irregular scaly pieces. The branches are spreading or obliquely spreading, the crown is broadly tower-shaped or umbrella-shaped, and the branches grow in one round a year, but in southern Guangdong they usually grow two rounds, yellowish brown, free of white powder, rare white powder, glabrous. Winter buds ovate-Terete or Terete, brown, tip pointed, bud scale margin filiform, apex pointed or acuminate long tip, slightly retrorse.

Leaf

Pine scale leaves solitary, linear, green when young, and then gradually degenerated into brown, membranous bract-like, drawing needles (secondary leaves) in its axils. Needles 2 needles a bunch, sparse 3 needles a bunch, 12 cm long, soft, slightly twisted, stomatal lines on both sides, margin serrulate, born on rudimentary short branches, the base of each bundle of needles is surrounded by membranous leaf sheaths. The leaf sheath was brown at first and then grayish black, persistent.

Flowers

The pine is monoecious and the cones are unisexual. Male cones solitary new branch lower bract axil, mostly aggregated, stamens numerous, anthers 2, anthers longitudinally lobed, pollen with two well-developed air sacs, airbag and body contact surface is small, the boundary is obvious, generally have significant margin. There are 1-4 female cones born near the top of new branches, with many pearl scales and bract scales, and two anatropous ovules are born at the ventral base of each scale. They are pollinated in the same year and will rapidly grow into cones in the second year.

Fruit

Some species of pine fruited earlier, a little in 5-6 years, significantly increased in 15-20 years, and some species fruited very late, such as Korean pine did not begin to bear fruit until 80-140 years under natural forest conditions. Cones mature for 2 years, seed scales open when ripe, sparsely not open, ovate, long ovate, suborbicular or cylindrical, erect or drooping. Species scale woody, persistent, the upper part of the exposed part is usually hypertrophic as a scale shield, with obvious transverse ridge or no transverse ridge, the apex or center of the scale shield has many verrucous protruding or retuse navel, spiny or unarmed, developed species with 2 kinds of scales. Upper part of seed with upper wing, cotyledons 3-18, unearthed at germination.