Plant of the Week
Woolly fleabane (Erigeron lanatus)
By Charmaine Delmatier, 2016
Woolly fleabane (Erigeron lanatus) is a member of the sunflower family, Asteraceae, the largest plant family in the world with 23,000 species. In North America, Eurasia, and Africa, there are approximately 200 species, with 62 occurring in North America. The genus Erigeron, commonly known as a fleabane, is a daisy-like flowering herbaceous forb in the sunflower family, Asteraceae, and has approximately 390 species worldwide with most occurring in temperate regions and 173 species in North America. The Greek derivative "eri" literally translates to early and "geron" means old man. It is an appropriate name since the flowers bloom in early spring and the plant has a hairy down that resembles the beard of an old man. According to distant folklore, gathering Erigerons in the wild and placing them inside a home prevents an unwanted infestation of fleas.
Because woolly fleabane is adapted to colder temperatures in the subalpine and alpine environment, it has a short window to flower, form fruit, and disperse seed, usually between July and August. Found on open exposed calcareous talus, rocky slopes, and fine gravels, it easily tolerates elevations between 6,880 to 13,354 feet. Hence, most all populations follow the backbone of the Rocky Mountains from Colorado to Alberta. With most populations occurring in Canada, there are a few disjunct populations in the lower forty-eight states, specifically in Colorado, Wyoming, and Montana. In all three states, it is considered rare. You will find woolly fleabane hidden in between shales and gravels for protection from harsh alpine winds and penetrating sunlight often associated with high-altitude mountain environment. Because it is threatened by an almost unavoidable death of desiccation, an ample covering of long villous hairs is one defense that lives up to its namesake as the beard of an old man. Its short height is also protection from locally harsh climates.
Adding to the above adaptations, it is well secured in the ground with fibrous roots and a slender-branched caudex. The flowering stems are only two inches tall with no leaves along the stem (scapose). The basal leaves are short, 1 to 3 centimeters long, apetiolate, and are usually entire with the tips sometimes one to three lobed. The hemispheric white to lilac flowering heads are large for such a diminutive plant, ranging from 8 to 12 millimeters tall. The darker phyllaries surrounding the involucre are in a 2 to 3 series, and the entire plant has shaggy wooly-villous, purple-tipped, minutely glandular hairs. The showy part of the plant by far is the ray florets numbering 30 to 80. They are straight, not recurved, and entire, with the ligules (flat part of the ray) 7 to 8 millimeters long. The inner yellow disk corollas are 4 to 5 millimeters long.
Erigerons can be easily confused with another closely related genus, Aster. A simple field characteristic to distinguish the two is to look at the appearance of the bracts (phyllaries) on the under-side of the flowering heads. Asters can have several rows of imbricate bracts, overlapping like roof shingles, but Erigerons have neatly uniform rows. With woolly fleabane, the neatly assembled series of two-three rows of phyllaries easily separate it out as an Erigeron.
The latest treatment in Flora of North America by Nesom and Noyes divides the Erigerons into sections by variations in ray arrangement (straight, reflexing, or coiling), arrangement and orientation of flowering heads (erect, nodding, or arching-pendent), type of root (taproot, rhizomes, or fibrous), and other morphological features. A favorite feature, if you can access a dissecting scope, is the purple cross-walls perpendicular to the long villous hairs. For such a small fleabane, it is a beauty.