Tall woolly head is a small woolly annual with erect and moderately branched stems arising from 1 cm to 15 cm high. The herbage consists of loosely arranged whitish hairs, giving plants a silk white or grayish appearance. The leaves are mostly opposite on the stems with individual leaves linear-oblong in shape, measuring up to 3.5 cm long and up to 6 mm wide. The leaves are generally 4.5-9 times as long as wide.
The flower heads are spherical and found at the tips of the branches. They are noticeably surpassed by their subtending leaves as shown in the photos. The bracts are about 3 mm long. There are from 50-80 female flowers in each head.
Tall woolly heads are similar to dwarf woolly heads Psilocarphus brevissimus , but the latter species is more typically prostrate and branched in form with the leaves tending to be widest near their base.
Tall woolly heads may be found in the drying beds of vernal pools and puddles and in ditches and along roadsides.
Tall woolly heads are found from southern British Columbia south into Oregon and Washington and east to southeastern Washington, northeastern Oregon and central Idaho. It is especially common in the Puget trough.