Fir

• 
  A. alba – the underside of leaves have two whitish strips formed by wax-covered stomatal bands; the bases of the needles are shaped like suction cups.
• 
  A. grandis foliage – upper side of the leaves
• 
  Atypical A. alba foliage from Dinaric calcareous fir forests on Mt. Orjen

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) [4]

The upper foliage is different on cone-bearing branches, with the leaves short, curved, and sharp.[5]

• 
  Intact and disintegrated Bulgarian fir cones
• 
  Immature cones of some species or races are green, not purple-bluish: for instance, Manchurian fir.
• 
  Disintegrating cones of Manchurian fir

Firs differ from other conifers in having erect, cylindrical cones 5–25 cm (2–10 in) long that disintegrate at maturity to release the winged seeds.

In contrast to spruces, fir cones do not hang. Even large fir cones grow upwards like "candles", the new growth of the tree.

Mature cones are usually brown, young in summer can be green, for example:

A. grandis, A. holophylla, A. nordmanniana

or purple and blue, sometimes very dark:

A. fraseri, A. homolepis (var. umbellata green), A. koreana ('Flava' green), A. lasiocarpa, A. nephrolepis (f. chlorocarpa green), A. sibirica, A. veitchii (var. olivacea green).[4]

Abies produce a variety of terpenoids. The analyses of the Zavarin group – from Smedman et al 1969 to Zavarin et al 1977 – showed variation in terpenoid composition of the bark by genetics, geography, age and size of the tree.[6][7]

Section Abies is found in central, south, and eastern Europe and Asia Minor.

• Abies alba – silver fir
• Abies nebrodensis – Sicilian fir
• Abies borisii-regis – Bulgarian fir
• Abies cephalonica – Greek fir
• Abies nordmanniana – Nordmann fir or Caucasian fir
  • Abies nordmanniana subsp. equi-trojani – Kazdağı fir, Turkish fir
• Abies pinsapo – Spanish fir
  • Abies pinsapo var. marocana – Moroccan fir
• Abies numidica – Algerian fir
• Abies cilicica – Syrian fir

Section Balsamea is found in northern Asia and North America, and high mountains further south.

• Abies fraseri – Fraser fir
• Abies balsamea – balsam fir
  • Abies balsamea var. phanerolepis – bracted balsam fir
• Abies lasiocarpa – subalpine fir
  • Abies lasiocarpa var. arizonica – corkbark fir
  • Abies lasiocarpa var. bifolia – Rocky Mountains subalpine fir
• Abies sibirica – Siberian fir
  • Abies sibirica var. semenovii
• Abies sachalinensis – Sakhalin fir
• Abies koreana – Korean fir
• Abies nephrolepis – Khinghan fir
• Abies veitchii – Veitch's fir
  • Abies veitchii var. sikokiana – Shikoku fir

Section Grandis is found in western North America to Mexico, Guatemala, Honduras and El Salvador, in lowlands in the north, moderate altitudes in south.

• Abies grandis – grand fir or giant fir
  • Abies grandis var. grandis – Coast grand fir
  • Abies grandis var. idahoensis – interior grand fir
• Abies concolor – white fir
  • Abies concolor subsp. concolor – Rocky Mountain white fir or Colorado white fir
  • Abies concolor subsp. lowiana – Low's white fir or Sierra Nevada white fir
• Abies durangensis – Durango fir
  • Abies durangensis var. coahuilensis – Coahuila fir
• Abies flinckii – Jalisco fir
• Abies guatemalensis – Guatemalan fir
  • Abies guatemalensis var. guatemalensis
  • Abies guatemalensis var. jaliscana
• Abies vejarii

Section Momi is found in east and central Asia and the Himalaya, generally at low to moderate altitudes.

• Abies kawakamii – Taiwan fir
• Abies homolepis – Nikko fir
• Abies recurvata – Min fir
  • Abies recurvata var. ernestii – Min fir
• Abies firma – Momi fir
• Abies beshanzuensis – Baishanzu fir
• Abies holophylla – Manchurian fir
• Abies chensiensis – Shensi fir
  • Abies chensiensis subsp. salouenensis – Salween fir
• Abies pindrow – Pindrow fir
• Abies ziyuanensis – Ziyuan fir

Section Amabilis is found in the Pacific Coast mountains in North America and Japan, in high rainfall areas.

• Abies amabilis – Pacific silver fir
• Abies mariesii – Maries' fir

A. fabri, Sichuan, China

Section Pseudopicea is found in the Sino – Himalayan mountains at high altitudes.

• Abies delavayi – Delavay's fir
  • Abies delavayi var. nukiangensis
  • Abies delavayi var. motuoensis
  • Abies delavayi subsp. fansipanensis
• Abies fabri – Faber's fir
  • Abies fabri subsp. minensis
• Abies forrestii – Forrest's fir
• Abies densa – Bhutan fir
• Abies spectabilis – East Himalayan fir
• Abies fargesii – Farges' fir
• Abies fanjingshanensis – Fanjingshan fir
• Abies yuanbaoshanensis – Yuanbaoshan fir
• Abies squamata – flaky fir

Section Oiamel is found in central Mexico at high altitudes.

• Abies religiosa – sacred fir
• Abies hickelii – Hickel's fir
  • Abies hickelii var. oaxacana – Oaxaca fir

A. magnifica, California, USA

Section Nobilis (western U.S., high altitudes)

• Abies procera – noble fir
• Abies magnifica – red fir
  • Abies magnifica var. shastensis – Shasta red fir

Section Bracteata (California coast)

• Abies bracteata – bristlecone fir
• ?†Abies rigida Frank Knowlton[11][12] - (Priabonian-Chattian; Colorado)

Section Incertae sedis

• †Abies milleri – (Extinct) Early Eocene[1]