Genus So.] 



THISTLE FAMILY. 



453 



80. DYSODIA Cav. Ann. Cient. Nat. 6: 334. 1801-2. 

 Erect or diffuse, branching, mostly annual, strong-scented more or less glandular herbs, 

 with opposite or alternate, mostly finely dissected leaves, and small peduncled heads of both 

 tubular and radiate yellow flowers. Involucre cylindric, campanulatc or nearly hemispheric, 

 its bracts in 1 series, united into a cup, usually with a few small additional outer ones. Re- 

 ceptacle flat, pubescent, or covered with short bristles. Pay-flowers pistillate, the rays 

 short. Disk-flowers perfect, their corollas 5-toothed. Anthers entire or minutely 2-toothed 

 at the base. Style-branches of the disk-flowers elongated, hirsute, sometimes apiculate. 

 Achenes narrowly obpyramidal, 3-5-angled, striate. Pappus of about 10 scales, patted to be- 

 yond the middle into numerous capillary, rather stiff, bristle-like segments. [Gretk, ill-smell.] 



About 15 species, natives of the south-central United States and of Mexico. Besides the fol- 

 lowing, 2 others occur in the southwestern United States. 



Fetid Marigold. 



False 



1. Dysodia papposa (Vent.) A. S. Hitchcock 

 Dog-fennel. (Fig. 3979.) 



Tagetes papposa Vent. Hort. Cels, pi. j6. 1800. 

 Boebera chrysantliemoid.es Willd. Sp. PL 3: 2125. 1804. 

 Dysodia chrysanthemoides Lag. Gen. etSp. Nov. 29. 1816. 

 D. papposa Hitchc. Trans. St. Louis Acad. 5: 503. 1891. 



Annual, very leafy, glabrous or finely pubescent, 

 gland-dotted, much branched, S'-iS' high, the branches 

 diffuse or erect. Leaves opposite, sessile, or short-peti- 

 oled, yz'-iYz' long, pinnately parted into linear or 

 slightly spatulate, sharply serrate or incised segments; 

 heads numerous, short-peduncled, 3 // -5 // broad; invo- 

 lucre campanulate, of 8-10 appressed oblong obtuse, 

 green or purplish, glabrous or ciliate bracts, with sev- 

 eral narrow shorter outer ones; rays few, not longer 

 than the width of the disk; receptacle and achenes 

 pubescent. 



Along streams and roadsides, Ohio to Minnesota and 

 Nebraska, south to Louisiana, Mexico and Arizona. Oc- 

 casionally found as a weed in waste places in the Eastern 

 and Middle States, and in Ontario. July-Oct. 



81. THYMOPHYLLA Lag. Gen. et Sp. Nov. 25. 1816. 

 [Hymenatherum Cass. Bull. Soc. Philom. 1817: 12. 1S17.] 

 Annual or perennial herbs, some species low undershrubs, with gland-dotted foliage and 

 involucre, alternate or opposite leaves, and small heads of both tubular and radiate, mostly 

 yellow flowers. Involucre campanulate, its principal bracts united into a cup, sometimes 

 with smaller outer ones. Receptacle naked, or fimbrillate, not chaffy. Ray-flowers pistil- 

 late, fertile. Disk-flowers perfect, fertile. Style-branches truncate or blunt. Achenes stri- 

 ate. Pappus of several or numerous scales or bristles. [Greek, thyme-leaf, not applicable 

 to the following species.] 



About 15 species, natives of America. Besides the following, some 4 others occur in the west- 

 ern parts of the United States. 



i. Thymophylla aurea (A. Gray) 

 Greene. Thyme-leaf. (Fig. 3980.) 



Lowellia aurea A. Gray, Mem. Am. Acad. (11)4:91. 



1849. 

 Hymenatherum aureum A. Gray, Proc. Am. Acad. 19: 



42. 1883. 



Annual, glabrous, 4 / -i2 / high, much branched; 

 the leaves and involucre with large oval oil-glands. 

 Leaves alternate, or the lower opposite, sessile, or 

 nearly so, very deeply parted into 5-9 linear-fili- 

 form, mostly entire, blunt segments; heads nu- 

 merous, corymbose, 6 // -io // broad, terminating 

 the branches; involucre about 3" high, its bracts 

 acute; rays about 12, 2j // -3 // long; pappus of 6-8 

 erose truncate scales, somewhat longer than the 

 thickness of the achene. 



Kansas and Colorado to Texas. June-Sept. 



