Asteraceae Erigeron Ochroleucus Nuttall

Erigeron ochroleucus Nuttall Asteraceae Synonyms: Erigeron ochroleucus var. scribneri Global Distribution: Western North American cordillera and disjunct more than 2,800 km in American Beringia.103 Alaska Distribution: Arctic Tundra, Intermontane Boreal. Ecoregions Occupied: Beaufort Coastal Plain, Yukon-Old Crow Basin. Conservation Status: S1S2 G5; BLM Watch. Description102, 103, 106 Upper leaf surfaces Ray florets white or less pubescent with short, commonly somewhat blue, 8 stiff, appressed hairs to 12 mm long Hairs on involucral bracts often have red-purple cross walls Lower leaf surfaces glabrous at least near tip, pubescent 1 cm with short, stiff, appressed hairs near the base Leaves narrow, 1 to 2 mm wide Illustration by Elizabeth Stephen, courtesy of Province of British Columbia 135 Erigeron ochroleucus General: Perennial herb from a taproot and a thick, woody, usually simple caudex; stems 2 to 15 cm tall, ascending to erect, pubescent with short, stiff, appressed hairs; stem height, leaf length and width, and color of cross walls on hairs of the involucral bracts of Alaskan plants differ from plants of more southern cordillera.103 Leaves: Basal leaves linear to linear-oblanceolate, 2 to 7 cm long, 1 to 2 mm wide; stem leaves reduced near the top, margins entire; lower surfaces glabrous at least near the tip, pubescent with short, stiff, appressed hairs near the base; upper surfaces pubescent with short, stiff, appressed hairs. Flowers: Flower heads usually solitary at the ends of stems; involucres 6 to 8 mm tall, 12 to 16 mm wide; involucral bracts arranged in three to four series, densely pubescent with stiff, long hairs that often have red-purple cross walls; ray florets 30 to 50, white or less commonly somewhat blue, 8 to 12 mm long; disc florets 3.5 to 4.5 mm long. Fruits: Achenes 2 to 2.5 mm long, sparsely villous; pappi in two series. © Matthew Lavin 2012 Ecology Elevation: Found from near sea level to 370 m in Alaska; up to 3,300 m elsewhere in North America.102 136 Erigeron ochroleucus Landform: Pingos and river banks in Arctic Tundra; river bluffs and river terraces in Intermontane Boreal. Soil Type: Gravel, sand. Moisture regime: Dry. Slope: Gentle to steep. Aspect: South to southeast to east on river bluffs. Vegetation type: Graminoid steppe, sparsely vegetated. Associated species: Artemisia frigida, Bupleurum americanum, Calamagrostis purpurascens, Carex rupestris, Dryas integrifolia, Erigeron caespitosus, Phlox hoodii, Potentilla uniflora, Pseudoroegneria spicata. Longevity: Perennial, moderately long-lived as evidenced by thick caudex on some specimens. Phenology: In the arctic, in flower July, possibly sooner, through early August; flowering June through August in more southern cordillera.102 Population estimate: There are nine known occurrences in Alaska; locally common along the Porcupine River.103 Reproductive biology: Likely pollinated by various insects including solitary bees, flies, and butterflies; Erigeron glabellus in interior Alaska is known to be pollinated by one fritillary butterfly species and three halictid bee species.105 Similar Species102, 103, 106 The table below shows morphological features that distinguish Erigeron ochroleucus from similar Erigeron species that occur in arctic Alaska and have narrow basal leaves less than 5 mm wide (at least sometimes), solitary flower heads (at least sometimes), and ray florets longer than 8 mm. Ray Species Leaf Hairs Involucral Hairs Florets Upper surfaces pubescent Pubescent with stiff, 8 to Erigeron with short, stiff, appressed long hairs that often 12 mm ochroleucus hairs; lower surfaces glabrous have red-purple cross long near tip walls Sparsely pubescent with Erigeron Both surfaces sparsely 5 to 9 mm long, soft hairs or purpuratus pubescent or glabrous long glabrous Pubescent with coarse, 7 to Erigeron Both surfaces pubescent with stiff hairs with purple- 15 mm hyperboreus stiff, coarse hairs black cross walls long 8 to Erigeron Both surfaces densely lanate; Densely lanate; hairs 13 mm muirii hairs tangled and wooly often somewhat yellow long 5 to Erigeron Both surfaces pubescent with Pubescent with coarse, 15 mm caespitosus short, stiff hairs stiff, white hairs long 137 Erigeron ochroleucus © Matthew Lavin 2012 © Bruce Bennett 2008 138 .

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