There are eleven genera in the family Pinaceae, all sharing certain morphological features such as (a) female cones (megaosporangiate strobili) which are usually just called “cones”, (b) male cones (microsporangiate strobili) which are sometimes called “catkins” or “pollen cones” and (c) needle-like leaves. Unlike the genus Pinus however, they are not all “evergreens” because two of these genera (Larix and Pseudolarix) have yearly deciduous leaves. All genera of the pine family have 12 pairs of chromosomes with two exceptions: Pseudotsuga (douglas fir) has 13 and Pseudolarix (false larch) has 11.
The family Pinaceae is the largest (in number of species and individuals), most geographically wide-spread and most economically significant of the conifers. There are about 260 species in this family and they cover most of the boreal forests of the northern hemisphere and extend at one point one degree south of the equator into northern Indonesia.
The largest genus in this family is Pinus which has about 120 species and subspecies and it accounts for much of the huge geographic spread.
The eleven genera are:
(1) Abies (true firs) (about 55 species): Have fairly wide-base single needles arising in a helical fashion, but on lower shaded branches are arranged pectinately, and they are set in circular depressions on the shoot. The cones are erect and are deciduous in one year. Pollen grains with two wings.
(2) Cedrus (true cedars) (4 species): Have long and short shoots with cones on the short shoots. Cones appear in late summer and are erect and are deciduous in one year. Leaves are single but arranged in false whorls and persist for several years. Solitary male cones on the ends of the short shoots.
(3) Larix (larches) (~15 species): Have long and short shoots with cones on the short shoots. Cones are erect and ripen in one year but persist and release seeds for a longer time. Leaves are single but arranged in false whorls and are deciduous in one year. Male cones on the end of leafless short shoots.
(4) Pseudolarix (false larches) (1 species): Same as Larix, but their cones are deciduous, i.e., breakup in situ and release seed at maturity within one year. 11 pairs of chromosomes (most of the pine family has 12 pairs). Male cones in clusters. Pseudolarix amabilis (Golden larch) from E. China.
(5) Cathaya (cathaya also the usual common name) (1 species). Resembles Larix and Cedrus in having long and short shoots, but develops cones on the long shoots whereas Larix and Cedrus develop female (and male) cones from the short shoots. Leaves somewhat whorled and nondeciduous. Cathaya argyrophylla from E. China.
(6) Keteleeria (~3 species, in China, Laos,Taiwan, and Vietnam): Resembles Abies, but the upright cones do not break up at maturity within one year. Also has hypogeal (underground) germination whereby the cotyledons stay below the ground surface and the true shoots emerge. Pollen grains with two wings.
(7) Picea (spruces) (~37 species): Leaves spirally arranged and four-sided and therefore relatively stiff and are set on a stem projection (the pulvinus) and therefore leave a rough twig after falling. The cones arise from the terminal cluster of buds at the ends of the shoots and up to the time of pollination are erect (like Abies) but then become pendulous. Pollen grains with two wings.
(8) Tsuga (hemlocks) (~10 species): Leaves with a knee-like bent petiole arising from a pulvinus and are constricted at the base (the petiole) and are notched and usually rounded at the ends. Cones small, ripening in the first year but remaining on the tree and not disintegrating (similar to Picea.) Pollen grains without wings.******
(9) Nothotsuga (Bristlecone hemlock) (1 species): Split off from the genus Tsuga in1989. Erect cones with exserted bracts. Male cones in clusters originating from a single lateral bud. Radially arranged leaves with stomatal lines on both surfaces. (These features resemble those of Keteleeria). Nothotsuga longbracteata, from S.E. China
(10) Pseudotsuga (Douglas firs) (~8 species): Leaves like Abies. Cones like Picea and Tsuga, but with exserted bracts (little, forked tabs at the ends of the cone scales). Also have sharp pointed cylindrical buds. Pollen grains without wings. 13 pairs of chromosomes.
(11) Pinus (pines) (~ 120 species): Needles in fascicles, of 1 to 8 needles, which can be fit together to form a cylinder. The female cones are fertilized in the second year and are variably persistent thereafter. Cone seed scales usually with a scale shield (apophysis). Male cones are many and clustered at the base of the current year’s long shoots. Pollen grains with two wings.