Petradoria pumila (Nutt.) Greene
Family: Asteraceae
Grassy Rock-Goldenrod,  more...
Petradoria pumila image

Stems 1-20+. Leaf blades 20-120 × 1-12 mm; cauline well developed, coriaceous, bases cuneate to attenuate, expanded laterally and abaxially, clasping, less so distally, apices acute to attenuate . Peduncles 1-5+ mm, glabrous or scabrous, resinous. Phyllaries mostly tan, 1-7 × 0.5-1+ mm, margins mostly entire, apices acute to attenuate (outer), obtuse to truncate, often mucronate (inner), a darker, thickened subapical gland often present. Ray florets 1-3, pistillate; corollas 4-8 mm, tubes 2-3.5 mm, laminae ± elliptic, 2.5-4.5 × 0.7-2.5 mm, lobes 0.5-1 mm; style branches 1-2 mm, linear-lanceolate, stigmatic lines extending around entire margin, appendages 0. Disc corollas 3.5-5.5 mm; style branches essentially lacking, stigmatic lines 0, appendages ± 1 mm, covered with collecting hairs. Cypselae of ray 4-5 mm; pappi 3.5-7 mm.

General: Perennial, 0.8-25 cm tall; stems 1-20, erect, slender, glabrous or minutely scabrous, often resinous; caudex woody, branched; tap-rooted.

Leaves: Basal and cauline, alternate, oblanceolate to linear-oblanceolate, 2-12 cm long, 1-12 mm wide, gradually reduced upwards, leathery, faintly to conspicuously gland-dotted, resinous, margins minutely scabrous; basal and lower cauline blades petiolate, upper cauline blades sessile.

Flowers: Heads solitary or few, arranged in corymb-like arrays; involucre campanulate, 3.5-5 mm long, and about as wide; phyllaries 12-16 in mostly 2 series; disk flowers only, 30-40, yellow to pale yellow; flowers June-October.

Fruits: Achene, 4-5 mm long, glabrous, 6-9 veined; pappus of 30- 60 tan, minutely barbed bristles.

Ecology: Dry, rocky, open habitats, slopes, canyons; 900-3000 m (3000-10000 ft); Apache, Coconino, Mohave, Navajo, and Yavapai counties; western and southwestern U.S.

Notes: Two varieties occur in our region and are differentiated as follows: var. graminea has narrower (1-2 mm wide), 1- veined or sometimes 3-veined leaves, involucres are narrow (1.3-2 mm wide) with 1 ray flower, and 2-3 disk flowers; var. pumila has broader (2-12 mm wide), 3-5 veined leaves, involucres are somewhat wider (1.9-3 mm wide), with 2-3 ray flowers and 2-4 disk flowers. The Hopi use rock goldenrod as a remedy for breast pain and to dry up the flow of milk. The Navajo use it for ant bites and injuries and as a ceremonial emetic.

Editor: Springer et al. 2008