"For beauty, give me trees with the fur on." -- Henry David Thoreau
What are the Close Relatives of Pines ?
(Members of the Pinaceae Family)
Newly planted cypress trees - Angelina Unit
the standing people, the trees,
only the cedar, the pine, the spruce, the laurel and the holly
had remained true to the Creator's instructions..."
Printed on the fans of the 47th Cherokee National Holiday Festival
There are eleven genera in the family Pinaceae, all sharing certain morphological features such as (a) "female" cones (macrosporangiate strobili) which are usually just called "cones", (b) "male" cones (microsporangiate strobili) which are sometimes called "catkins" or "pollen cones" and (c) needlelike 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 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 larch) [1 species, in China]: Same as Larix, but their cones are deciduous, i.e. breakup and release seed at maturity within one year. 11 pairs of chromosomes (most of the pine family has 12 pairs).
(5) Cathaya [1 species, in China]: 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 non-deciduous.
(6) Keteleeria [10 species, in China, Laos, Taiwan and Vietnam]: Resembles Abies, but the upright cones do not break up at maturity with in 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 therefor relatively stiff and are set on a stem projection (the pulvinus) and therefor 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 (a hemlock from SE China, often still included in the Tsuga genus) [1 species].
(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) [about 120 species]: Needles in fascicles (of 1 to 8) 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.
** A possible 12th future new genus may be necessary for
Mountain Hemlock (Tsuga mertensiana), now classified in the genus
Tsuga (hemlocks). There are obstacles in classifying Mountain
Hemlock in the genus Tsuga which include gross and microscopic
morphological features. These are (a) larger cones (approx.
3" for mertensiana vs. approx. 1" for other species),
(b) needles carried radially and thicker and longer than in other
Tsuga species, (c) stomata on dorsal and ventral surfaces vs.
only on ventral surfaces for other Tsuga species and (d) pollen
grains with a pair of lobes ("wings") attached (same as
pines, firs and spruces) whereas other Tsuga species have bowl
shaped pollen grains (like larches and Douglas firs). Once Tsuga
mertensiana was named Hesperopeuce mertensiana, however,
most taxonomists don't think these differences are sufficient for
the creation of this new genus and so, for now, the mountain
hemlock occupies its own section of Hesperopeuce (all other
hemlocks are in the Micropeuce section) of the genus Tsuga.
Ronald Lanner (see reference "Trees of the Great Basin") suggests that Mountain Hemlock may be ancient hybrid between Western Hemlock and Sitka Spruce, which would explain some of its spruce-like morphological features.
This tree was described by John Muir as "the most singularly beautiful of all the California conifers" and it will be interesting to see if taxonomists eventually reassign it to a new genus of its own.
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