. Carnegie Institution of Washington publication. 100 THE ECOLOGICAL RELATIONS OF ROOTS. VIII. THE FOREST COMMUNITY. A forest community finally occupies the half-gravel-slide. It is represented by Pinus ponderosa or Pseudotsuga mucronata, both of which are frequently preceded by a chaparral stage. Along the streams and moister slopes, Douglas fir meets the Engelmann spruce, Picea engelmanni, with which it often forms a mictium. A rather large number of herbs and undershrubs characteristic of the more mesophytic type of forest were examained (plate 27, a, b). Pirola chlorantha.—^This evergreen
. Carnegie Institution of Washington publication. 100 THE ECOLOGICAL RELATIONS OF ROOTS. VIII. THE FOREST COMMUNITY. A forest community finally occupies the half-gravel-slide. It is represented by Pinus ponderosa or Pseudotsuga mucronata, both of which are frequently preceded by a chaparral stage. Along the streams and moister slopes, Douglas fir meets the Engelmann spruce, Picea engelmanni, with which it often forms a mictium. A rather large number of herbs and undershrubs characteristic of the more mesophytic type of forest were examained (plate 27, a, b). Pirola chlorantha.—^This evergreen herb is very abundant and foiins extensive clans on the floor of the spruce forest. The clusters of leaves arise at intervals from a few inches to more than a foot from the glistening white underground stems. These vary from 1 to 3 mm. in diameter, branch freely, and form a connecting system for the individual plants. They lie at a depth varying from inch to about 5 inches. Just before the rootstock approaches the surface to send up a cluster of leaves, it invariably branches, the branch continuing to the next plant, etc. The root system is very meager and con- sists of brownish roots arising at irregular intervals, usually about 1 inch apart on the horizontal rootstock, although it is not unusual to find several inches of the rootstock practically free from rootlets. These roots penetrate the moist duif and rich humus soil to a depth of only 6 to 10 inches; while many of them are only 1 to inches long, others form brush-like clusters 3 to 5 inches in length (fig. 42).. Fig. 42.—Pirola chlorantha. Thalictrum fendleri.—This polydemic ranges in habitat from the half- gravel-slide, into which it has worked its way from the bordering woodland, to dense spruce forest. In the Douglas fir forest it forms extensive societies. The plants here described were examined in a spruce forest. The slender tops of these plants arise from a meager system of rhizomes almost black in
Size: 1660px × 1504px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1910, bookyear1919
