Structure and Development of Sumac Clones

Abstract

Studies of thirteen clones of Rhus glabra, the smooth sumac, yielded information on height, age, incomplete development of twig, branching angles, size of clone, average annual growth, direction of growth, numbers of stems of each age class, and location of new growth. One clone was partially excavated, and one clone showing considerable mortality of upper twigs was studied. The major conclusions drawn are: 1) the stems range in height from 0.4 m to 3.0 m and in age from one to fifteen years; 2) the tallest stems tend to be the oldest; 3) of the buds observed, 56% did not undergo complete development to the stage of flowering or fruiting; 4) branch- ing angles differ significantly from clone to clone; 5) one clone has been shown to be a vegetative development of one individual; 6) the area covered by one clone may be as much as 22 by 40 m; 7) average annual spread of a clone is 94 cm per year; 8) the pattern of growth is one- sided; 9) the number of new stems varies from year to year; 10) the percentage of new stems which occupy territory outside the previous clonal boundary tends to decrease in successive years; 11) a stem may arise from a rhizome several years old; 12) one clone was found to be dying in the center. METHODS Ten of the clones considered grew in old-field sites in Stinchfield Woods in the northeastern portion of Dexter Twp., Washtenaw Co., Michigan. These were clones A-I and clone K. One clone, J, grew in the extreme southeastern corner of Erie Co., Ohio. The remaining two clones grew in Cheboygan Co., Michigan; clone L in Sec. 31 of Munro Twp., and clone M in Sec. 28 of Burt Twp. (Clones A-1 are identical with the nine clo,nes whose phenology was reported upon previously; Gilbert, 1961.) In nine clones, A-I, reference stakes were set out, and the outline of the clone was mapped about its reference points. The height of the stems was added to the map as isochores of stem height. The clone was divided into four sectors centered on the tallest portion of the clone by northeast, southeast, southwest, and northwest radii. In addition 5-foot interval contours of altitude above sea level were superimposed o,n the clone outline. A sampile section of the clone was designated by lines representing topography, height of the stem, and exposure within the clone. The number of sample sections varied from 6 to 21 with variation in height'and topography. Within each sample section, a sample area was chosen with a table of random numbers and within the sample area three stems were chosen, again