Monographs Details: Hackelia diffusa var. cottonii (Piper) R.L.Carr
Authority: Gentry, Johnnie L. & Carr, Robert L. 1976. A revision of the genus Hackelia (Boraginaceae) in North America north of Mexico. Mem. New York Bot. Gard. 26: 121-227.
Description:Variety Description - Perennial, 2-6 dm tall; herbage green, stems few to several, erect or ascending, antrorsely strigose in the inflorescence, retrorsely strigose below, or if spreading then the hairs generally turned downward. Radical leaves often very many, petiolate for 1/3-1/2 their length, (10-)14-22(-31) cm long, (4-)ll-18(-31) mm wide, elliptic, pubescence fine, strigose or often rather strongly spreading; lowermost cauline leaves 9-16 cm long, 5-11 mm wide, linear or narrowly elliptic, petiolate, early deciduous, becoming lanceolate at midstem, 5-10 cm long and 6-12 mm wide, reducing upwards to minute bracts in the inflorescence. Pedicel 7-9(-12) mm long in fruit. Calyx 2.2-4.0 mm long, linear-lanceolate. Corolla limb cream-colored, less often white, rarely washed with blue, the throat yellowish, 8-11(-13)mm wide. Fomices with appendages rather short-papülate-puberulent, emarginate. Anthers 0.8-1.l(-1.4)mm long. Nutlets 3.4-4.0 mm long, ovate; dorsal surface often strongly verrucose-hispidulous, the intramarginal prickles distinct, 16-23; prominent marginal prickles 2-3 mm long, alternating with much shorter glochidia. Chromosome number, 2n = 48.

Discussion:Lappula cottonii Piper, Bull. Torrey Club 29: 549. 1902 (as “Cottoni”). Hackelia cottonii (Piper) Brand, Pflanzenr. IV. 252(Heft 97): 132. 1931 (as “Cottoni”). Lappula hendersonii Piper, Bull. Torrey Club 29: 539. 1902 (as “Hendersoni”). Hackelia hendersonii (Piper) Brand, Pflanzenr. IV. 252(Heft 97): 132. 1931. Type: WASHINGTON. Yakima County: Clemens Mountain, June 14, 1892, L. F. Henderson s.n. (holotype, US!). Type. WASHINGTON. North slope of Rattlesnake Hills, May 11, 1901, J. S. Cotton 360 (holotype, WS!; isotypes, GH!, US!, WTU!, PH!). Hackelia diffusa var cottonii can be separated from var diffusa by its much shorter, often strigose pubescence. It rarely has any blue coloration in its typically smaller corolla; the nutlets are often stouter, and the intramarginal prickles, although greater in number, are shorter than those of var diffusa. One can find forms intermediate between these two varieties in that portion of the Columbia River Gorge from about Hood River to The Dalles. This represents a rather short distance geographically but is an area of significant change in environmental conditions. The area to the west of Hood River is strongly influenced by the coastal weather and therefore has a higher annual precipitation and a moderate, less variable temperature regime than that found east of The Dalles. The environmental conditions found east of The Dalles are strongly influenced by the interior land mass and are therefore quite dry and subject to rather drastic winter and summer extremes of temperature. Hackelia diffusa var cottonii is separated from var arida also on the basis of pubescence. The herbage of var arida has a much more dense covering of hairs, which are quite often of two distinct sizes. The appendages in var arida tend to be papillate-hairy as opposed to the shorter papillate-puberulent condition of var cottonii. Where the two varieties meet in the Yakima region, intermediates occur, and it is fairly common to find plants with appendages like those described for var arida, but having leaves and pubescence similar to that of var cottonii. The opposite combination of characteristics is also common, as well as, various intermediates to the above conditions. The following short descriptions characterize the three elements of Hackelia diffusa. Emphasis is put on tendencies in the variation patterns of each variety, so the characteristics used are not necessarily widespread or stable in a particular taxon. Hackelia diffusa var diffusa: Plants moderately tall, mostly 4-5 dm; herbage dark-green; pubescence long, spreading, uniform, moderately dense; basal leaves rather broadly elliptic, thin; corolla blue, appendages short papillate-puberulent; intramarginal prickles few to many and long; marginal prickles distinct to their bases. Hackelia diffusa var cottonii: Plants variable in stature but often short, 2-5 dm tall; herbage green; pubescence short, appressed or spreading, uniform, sparse; basal leaves rather narrowly elliptic; corolla cream-colored, appendages short papillate-puberulent; intramarginal prickles many and long or short; marginal prickles distinct to their bases. Hackelia diffusa var arida: Plants tall, mostly 5-6 dm; herbage bluish-green; pubescence often of two size ranges, spreading and/or appressed, very dense; basal leaves linear; corolla white, appendages papillate-hairy; intramarginal prickles few and short; marginal prickles often connate for one-third (one-half) their length.
Distribution:United States of America North America|