pinopsida

Pinaceae Leaves

Field botanists often have clever ways to identify species that are difficult to distinguish from each other without a microscope or reference. Usually the scientific basis or mechanism of such a “test” is unknown, but the test is reliable enough to be widely used. The amount and pattern of cell wall lignification (blue-white fluorescence) in the internal tissues of these two superficially similar looking pine needles has been determined to be the causal basis for the “leaf bending test,” often used to discriminate these two species in the field. Careful biophysical and anatomical analyses revealed that Pinus nigra (top) appears flexible when bent due to a relative lack of internal lignification. Its structural integration causes the leaf structure to fail in compression via a succession of crimping on the flat adaxial face of the leaf. In contrast, Pinus resinosa (bottom) “snaps” at the rounded vertex of the leaf when bent as a result of resistance to tensile forces transmitted through the highly integrated internal leaf tissue, which is provided by the relative abundance of lignification in the walls of the mesophyll cells and the thick lignified periclinal walls of the endodermal cells (Meicenheimer et al., 2008).

Image courtesy of Eric M. Chapman.

Caucasian Fir - Abies nordmanniana bornmuelleriana

Also referred to as Kazazdagi Fir, and Nordmann Fir, Abies nordmanniana (Pinales - Pinaceae) is an evergreen conifer making a large tree to 30m or more, with narrow conical or columnar crown, with dense, glossy dark green foliage on down-swept branches. The young cones are green or reddish, becoming brown with age.

The species forms extensive forests which are largely intact and has a widespread distribution throughout the Black Sea Region of northwestern Turkey, eastwards to the western Caucasus. The subspecies pictured, Abies nordmanniana bornmuelleriana, is endemic to Turkey.

References: [1] - [2]

Photo credit: ©Hasan Yasayacak | Locality: Ilgaz, Kastamonu, Black Sea, Turkey (2012)

Name: Walchia angustifolia

Location: Texas, USA, Admiral Formation

Age:268-293 million years ago, Permian Period

The only remains scientists found at a site were fossils of the tree Walchia, dragonfly wings, ancient animal tracks, and cracks in prehistoric mud. When analyzed with the alternating layers of sand and mud left behind by water almost 300 million years ago, the evidence was enough to reconstruct an ancient environment.

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Norway spruce - Picea abies

The Norway spruce, Picea abies (Pinaceae), is a large pyramidal evergreen conifer that is native, widespread and dominant in Boreal conifer forests of North and Northeast Europe. 

Cones are very large, cylindrical, 4 to 6 inches long, with stiff, thin scales that are irregularly toothed, chestnut brown, maturing in fall.

References: [1] - [2] - [3]

Photo credit: ©Rieko S. | Locality: New York, US (2012) 

Black Spruce - Picea mariana

These are female cones of Black Spruce, Picea mariana (Pinales - Pinaceae), a wide-ranging, abundant conifer of the northern parts of North America. Its wood is yellow-white in color, relatively light in weight, and strong. Black spruce is the most important pulpwood species of Canada and is also commercially important in the Lake States, especially Minnesota.

Reference: [1]

Photo credit: ©Bruno Bergeron | Locality: not indicated (2014)

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