Adenocaulon bicolor

pathfinder

Asteraceae

The Basics

Plant Guide

Jepson eFlora

Adenocaulon bicolor, commonly known as trail plant or Pathfinder, is a fibrous rooted perennial herb with a single, slender stem up to 1 meter tall. Leaves are primarily basal and long-petioled with large, thin, triangular leaf blades. The leaf surfaces are green and glabrous above and white-wooly beneath.

It is called Pathfinder because the underside of its leaves - which can be overturned when people walk past - are highly noticeable and suggest recent human traffic.

Ranges from southern British Columbia to California and east to northern Idaho and northwestern Montana. Disjunct populations occur in the Black Hills of South Dakota and Wyoming and in the northern Great Lakes area. Wyoming populations are restricted to Crook County. It is found primarily on shady, north-facing lower slopes and bottoms on moist organic soils.

Identification

Perennial herb 3-10 dm, generally erect, openly branched, proximally tomentose, distally stalked-glandular. Leaf: petiole winged; blade 3-25 cm, triangular to ovate, entire to shallowly lobed, abaxially white-tomentose, adaxially glabrous, base truncate to cordate or hastate.

Inflorescence: phyllaries 1-2.5 mm, ovate. Pistillate flower: 3-7; corolla 0.5-1 mm. Disk flower: 2-10; corolla 1.5-2 mm. Fruit: 5-9 mm, club-shaped. 2n=46. Generally in shade, woodland, forest; < 2000 m. (Jepson eFlora)

Threats

Adenocaulon bicolor's unique leaves allow it to obtain the limited sun abaliable to it. While this plant is adapted to limited amounts of sun when it obtains too much it has detrimental consequences. If the sun stays on the leaves for a longer period then the 1-hour time at noon, the photosynthetic rate decreases. Thus, making the way their leaves are specifically designed useless.

Reproduction

The flowering and fruiting period for Adencaoulon bicolor occurs between June and July. The head of the flower opens and pollen is dropped into the flower. Flower heads are small and contain 6-14 whitish disk flowers. Once the seeds has formed the flowers drip away and seeds are dispersed.

Species Distribution

Citation

The Importance of Sunflecks for Forest Understory Plants
Chazdon, R. L., & Pearcy, R. W. (1991). The importance of sunflecks for forest understory plants. BioScience, 41(11), 760-766.

Flowers of Adenocaulon bicolor
Ayres, J. A. (1915). Flower of Adenocaulon bicolor. Botanical Gazette, 59(2), 154-157.

The Functional Morphology of Light Capture and Carbon gain in the Redwood Forest Understorey plant Adenocaulon bicolor Hook
Pearcy, R. W., & Yang, W. (1998). The functional morphology of light capture and carbon gain in the Redwood forest understorey plant Adenocaulon bicolor Hook. Functional Ecology, 12(4), 543-552.

USDA Plants Database
USDA, NRCS. 2016. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.

Flora of North America Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.

Burke Museum of Natural History and Culture
Burke Museum. 2016. Adenocaulon bicolor [Online]. University of Washington.

The Jepson Herbarium
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA.