Kelley et al 2014 (Jepson Manual Online), Heil et al 2013

Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Annual herbs, 10-80 cm tall; stems branching above the middle; herbage puberulent or shortly hirsute. Leaves: Alternate; upper leaves sessile and lower leaves on petioles 1-2 cm long; blades linear to oblong, 1- 6 cm long; basal leaves often deciduous. Flowers: Inconspicuous and tiny, on 1-2 mm pedicels and arranged in racemes, each flower subtended by a leaf-like bract; calyx deeply 5-lobed, enlarging to 3 mm long in fruit, the lobes lanceolate and erect in fruit; corolla white to light blue, 2 mm diameter, 5-lobed. Fruits: Nutlets 4 per fruit, each 2-3 mm long, with a single marginal row of prickles, these often swollen and confluent toward the base, forming a cupulate border to the nutlet. Ecology: Found in sunny, usually disturbed sites, roadsides, overgrazed areas, below 8,500 ft (2590 m); flowers March-September. Distribution: Widely distributed throughout much of N. Amer., in every state west of the Mississippi, north to AK and south to n MEX; also in S. America. Notes: A small annual herb, fuzzy all over, with narrow leaves and tiny white to light blue flowers; the fruits are distinctive, being 4 nutlets with marginal, hooked prickles which attach to the socks of passers by. Two varieties are found in Arizona: var. cupulata is a multi-stemmed plant with the nutlet prickles confluent into a swollen, cup-shaped base; var. occidentalis is a single or few-stemmed plant with nutlet prickles slightly confluent at the base but not swollen. Distinguish from L. squarrosa by the nutlets which in that species have at least 2 rows of slender, distinct marginal prickles. L. occidentalis has been considered synonymous with L. redowskii but Heil et al.-s recent San Juan Flora claims that L. redowskii is an Old World species that does not exist in North America. Ethnobotany: Navajo use it to make poultice for insect bites and other skin irritations. Etymology: Lappula is the Latin diminutive for lappa, a bur; occidentalis means of the west. Synonyms: Echinospermum redowskii var. occidentale, Echinospermum occidentale, Lappula echinata var. occidentalis, Lappula redowskii subsp. occidentalis, Lappula redowskii var. occidentalis Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2016