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Western Wetland Flora

Field Office Guide to Plant Species

Sticky-leaf Arnica
Arnica diversifolia Greene

JPG -- Species Photo JPG -- Distribution Map

Family: Composite (Compositae)
Flowering: July-September
Field Marks: This Arnica has 3 or 4 pairs of irregularly toothed leaves on the stem, flower heads with 8-15 pale yellow rays 3/4-1 inch long, and tawny-colored soft bristles on the achenes.
Habitat: Wet, often rocky, areas.
Habit: Perennial herb with branching rhizomes.
Stems: Upright, unbranched, up to 15 inches tall, smooth or glandular-hairy.
Leaves: Leaves on the stem 3-4 pairs, opposite, elliptic to ovate, up to 2 1/2 inches long, up to 2 1/2 inches wide, rounded or pointed at the tip, rounded at the base, irregularly toothed, rough-hairy, sessile or on short stalks; basal leaves,
Flowers: Crowded into heads, with few to several heads at the tip of the stem; heads up to 2 inches across, bearing both ray flowers and disk flowers; heads subtended by pointed, narrow, green bracts that have some long hairs, some of which may
Sepals: 0.
Petals: Some united to form 8-15 pale yellow rays 3/4-1 inch long; others united into tubes that comprise the central yellow disk.
Stamens: 5.
Pistils: Ovary inferior, hairy.
Fruits: Achenes short-hairy, with tawny soft bristles at the tip.
Notes: This is a rather variable species, similar to A. mollis but differing mostly by having the stem leaves larger than the basal leaves.

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Page Last Modified: Saturday, 02-Feb-2013 06:26:55 EST
Menlo Park, CA [caww55]