Шыршы ағаштарының сипаттамасы

Genus of plants in the conifer family cedar

Automatic taxobox
| name = Fir
| fossil range = Eocene Present extant species, found on mountains throughout much of North and Central America, Europe, Asia, and North Africa. The genus is most closely related to Cedrus (cedar). The genus name is derived from the Latin "to rise" in reference to the height of its species. The common English name originates with the Old Norse, fyri, or the Old Danish, fyr. They are large trees, reaching heights of tall with trunk diameters of when mature. Firs can be distinguished from other members of the pine family by the way in which their needle like leaves are attached singly to the branches with a base resembling a suction cup, and by their cones, which, like those of true cedars, stand upright on the branches like candles and disintegrate at maturity. Identification of the different species is based on the size and arrangement of the leaves, the size and shape of the cones, and whether the bract scales of the cones are long and exserted, or short and hidden inside the cone.

Firs can be distinguished from other members of the pine family by the unique attachment of their needle like leaves to the twig by a base that resembles a small suction cup. The leaves are significantly flattened, sometimes even looking like they are pressed, as in A. sibirica. The leaves have two whitish lines on the bottom, each of which is formed by wax covered stomatal bands. In most species, the upper surface of the leaves is uniformly green and shiny, without stomata or with a few on the tip, visible as whitish spots. Other species have the upper surface of leaves dull, gray green or bluish gray to silvery (glaucous), coated by wax with variable number of stomatal bands, and not always continuous. An example species with shiny green leaves is A. alba, and an example species with dull waxy leaves is A. concolor. The tips of leaves are usually more or less notched (as in A. firma), but sometimes rounded or dull (as in A. concolor, A. magnifica) or sharp and prickly (as in A. bracteata, A. cephalonica, A. holophylla). The leaves of young plants are usually sharper. The way they spread from the shoot is very diverse, only in some species comb shaped, with the leaves arranged on two sides, flat (A. alba)

The oldest pollen assignable to the genus dates to the Late Cretaceous in Siberia, with records of leaves and reproductive organs across the Northern Hemisphere from the Eocene onwards.