From fvhsu@hotmail.com Sun Dec 14 14:49:44 1997 Date: Mon, 24 Nov 1997 06:08:30 PST From: Felix Hsu To: vespirus@socrates.berkeley.edu Subject: Web Project: Group 2...Systematics Brian... Finally here it is the final version of the web project. I have two pages of the web project; Francis should have the other three. I have the Introduction and the Systematics pages. I will send them to you separately. Felix This is the SYSTEMATICS ******************************* Systematics of Pinaceae

Pinaceae:More on Systematics

The family Pinaceae was established by Lindley (1836) as a distict group of coniferous trees containing many genera. The family Pinaceae is presently classified in the order Coniferales, the largest group of conifers, with four other families: Araucariaceae, Cupressaceae, Podocarpaceae and Taxodiaceae. Cephalotaxaceae are sometimes included but are probably more closely related to Taxaceae. There are 10 genera accepted as of now. The following 10 genera, listed with the number of accepted species in parentheses, are recognized in Pinaceae: Abies (55), Cathaya (1), Cedrus (4), Keteleeria (4), Larix (15), Nothotsuga (1), Picea (37), Pinus (120), Pseudolarix (1), Pseudotsuga (8), and Tsuga (10).

The inter-generic relationships in the family Pinaceae are difficult to determine. Many people in the past have discussed these inter-relationships. Since then, these discussions have led to several classifications. One classification given by Melchior Werdermann has been accepted by many. The way in which they classified the subfamilies were by certain differences. The subfamily Pinoideae are said to have shoots and foliage that are strongly dimorphic and the strobili are located on long shoots. The subfamily Laricoideae Melchior Werdermann's shoots are dimorphic but the foliage are monomorphic. There strobili are located on short shoots. The subfamily Abietoideae Pilger have shoots that are not dimorphic or are only weakly dimorphic. The foliage are monomorphic and the strobili are located on long shoots. But if other characters of the various genera are considered, many problems may occur with this classification. Among these are characters of the male and female cones, the seeds, the cotyledons, pollen type, wood anatomy and biochemistry, which cannot be ignored in a classificaion that is supposed to represent a theory of phylogeny. This type of classification, based on the theory of phylogeny, must be based on a comparison of many homologous characters and should preferably be monophyletic at the same time.

Based upon the theory of phylogeny, this classification arose:
Family Pinaceae Lindl. (Type: Pinus)
---Subfam. Pinoideae
-----Gen. Pinus
---Subfam. Piceoideae Frankis
-----Gen. Picea
---Subfam. Laricoideae Melchior et Werdermann
-----Gen. Cathaya, Pseudotsuga, Larix (type)
---Subfam. Abietoideae Pilger
-----Gen. Cedrus, Abies (type), Pseudolarix, Keteleeria, Nothotsuga, Tsuga

The species in the genus Pinus is classified under this category because of certain characteristics. For example, when putting certain species under the genus Pinus, that species must have the same characteristics as the following: Pinus's root anatomy consists of two resin canals in vascular cylinder of young taproot. The wood anatomy consists of resin canals (both vertical and horizonatal) Micropylar fluid is found in the female cone and there is a prolonged female cone maturation(2-3 years). Shoot and leaf dimorphism are very pronounced. Seed scales of cones contain umbo and seeds are held in claws to the wing.

Systematics is a very complicated task. As said before, it requires a lot of knowledge of certain characteristics that might not be available. Therefore, the classification of certain genus or of anything is constantly changing.

Source:

Farjon, Aljos. Pinaceae, drawings and descriptions of the Genera Abies, Cedrus, Pseudolarix, Keteleeria, nothotsuga, Tsuga, Cathaya, Pseudotsuga, Larix, Picea. Koenigstein, Federal Republic of Germany. Koelto Scientific Books, 1990.

______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com