Solidago altissima

Solidago altissima, the tall goldenrod or late goldenrod, is a North American species of goldenrod in the family Asteraceae which is widespread across much of Canada, the United States, and northern Mexico. It is common in much of its range and fairly tolerant of landscapes which have been disturbed by humans. It has become naturalized in many parts of the world.

Solidago altissima is one to two meters (40 to 80 inches) in height with fine hairs on the stem. The leaves are located along the stem, not in a rosette near the ground. One plant can produce as many as 1500 small yellow flower heads in a large conical array. The involucres of the main subspecies (S. a. subsp. altissima) are usually 3–4 millimeters, whereas those of S. a. subsp. gilvocanescens are usually 2–3 mm.

Solidago altissima has a base number of nine chromosomes (x = 9). Diploid, tetraploid, and hexaploid plants with respective chromosome counts of 18, 36, and 54 have been reported among the two subspecies.

Solidago altissima has diploid, tetraploid, and hexaploid populations as well as morphological variations which have generally led to classifying it into two subspecies. Roughly speaking, these subspecies can be identified as being from the eastern and western parts of the North American continent. At least in the Midwest, it is common to have plants of different ploidy interspersed, with little apparent tendency for one type to dominate even a fairly local geographical area.

Within Solidago, S. altissima is part of the Solidago canadensis species complex, which is classified in the subsection Triplinervae. S. altissima sometimes has been classified as an infraspecies of S. canadensis.

S. altissima is widespread across much of Canada, the United States, and northern Mexico. It is common in much of its range and fairly tolerant of landscapes which have been disturbed by humans.

S. a. subsp. altissima is in eastern Canada except Newfoundland and Labrador, and it is in the provinces of Saskatchewan and Manitoba. In the United States, it is east of the Mississippi River except Wisconsin, Illinois, and North Carolina; all U.S. states directly on the west of the Mississippi River; and, Nebraska, Kansas, Oklahoma, Texas, Utah, Arizona, and California. In Mexico, it is in the north except on the Baja California Peninsula, Sonora, and Sinaloa. It is in all other states as far south as Oaxaca and Veracruz except Mexico, Morelos, Puebla, Tlaxcala, and Mexico City. It is native in all of the above states and provinces where it resides. It is an introduced species in East China, South Central China, Taiwan, New South Wales, Korea, and Transcaucasus.

S. a. subsp. gilvocanescens (Rydb.) Semple is in western Canada and Ontario. In the United States, it is only east of the Mississippi River in Illinois and is then distributed west through the Great Plains states. In Mexico, it overlaps S. a. subsp. altissima except in the west.