Genus 13.] 



THISTLE FAMILY. 



321 



About 25 species, natives of western North America, Peru and Chili. Besides the following, 

 some 9 others occur in the western and southwestern parts of North America. Known as Gum- 

 plant or Tar- weed. 



Leaves spatulate or oblong-, obtuse or obtusish; achenes truncate. i. G. squarrosa. 



Leaves linear or linear-oblong, acute; achenes 2-toothed. 2. G. lanceolala. 



i. Grindelia squarrosa (Pursh) Dunal 



(Fig. 3649. ) 



Donia squarrosa Pursh, Fl. Am. Sept. 555. 



1S14. 

 Grindelia squarrosa Dunal in DC. Prodr. 5: 



315. 1836. 



Glabrous, erect or ascending, branched, 

 lo / -2 high. Leaves oblong or oblong- 

 spatulate, obtuse, more or less clasping at 

 the base, sharply spinulose-dentate, some- 

 times laciniate,% / -i>^ / long, 3 // -6 // wide; 

 heads io // -i5 // broad, very glutinous; 

 bracts of the involucre linear-lanceo- 

 late, subulate- tipped, strongly squarrose; 

 achenes truncate, those of the outer flow- 

 ers usually thicker than those of the in- 

 ner; pappus of 2 or 3 awns. 



In dry soil, Illinois and Minnesota to Mani- 

 toba, south to Missouri, Texas, Nevada and 

 Mexico. Adventive in southern New Jersey. 

 June-Sept. 

 Grindelia squarrosa nuda (Wood) A. Gray, 



Syn. Fl. 1: Part 2, 118. 1884. 

 Grindelia tiuda Wood. Bot. Gaz. 3: 50. 1878. 



Rays wanting. Missouri and westward 

 with the type. 



Broad-leaved Gum-plant. 



2. Grindelia lanceolata Nutt. 



Narrow-leaved Gum-plant. 



(Fig. 3650.) 



Grindelia lanceolata Nutt. Journ. Acad. 

 Phil. 7: 73. 1834. 



Slender, erect, glabrous, branched, about 

 2 high. Leaves lanceolate or linear, 

 acute at the apex, sessile or clasping at 

 the base, spinulose-dentate, laciniate, or 

 the upper entire, i / -2 / long, 2 // -5 // wide; 

 heads nearly as large as those of the pre- 

 ceding species; bracts of the involucre 

 linear-subulate, the inner erect, the outer 

 spreading; achenes 2-toothed; pappus of 

 1 or 2 awns. 



In dry soil, Tennessee to Kansas, Louisiana 

 and Texas. July-Sept. 



13. HETEROTHECA Cass. Bull. Soc. Philom. 1817: 137. 1817. 



Erect, hirsute or pubescent, branching herbs, with alternate, mostly dentate leaves, and 

 rather large heads of both discoid and radiate yellow flowers, generally solitary at the ends 

 of the branches. Involucre hemispheric or broadly campanulate, its bracts imbricated in 

 several series, the outer shorter. Receptacle flat, alveolate. Ray-flowers pistillate. Disk- 

 flowers perfect, or some of them only staminate. Style-branches flat, their appendages 

 lanceolate or triangular. Achenes pubescent, obtuse, those of the ray-flowers thick, those 

 of the disk-flowers flattened. Pappus of the ray- flowers obsolete or of a few caducous bristles, 

 that of the disk-flowers of an inner row of numerous capillary rough bristles, and an outer 

 row of shorter stouter bristles or scales. [Greek, different-case, from the dissimilar achenes. ~\ 



Five or 6 species natives of the southern United States and Mexico. 



21 



