Gen'i-s So.] 



THISTLE FAMILY. 



453 



80. DYSODIA Cav. Ann. Cient. Nat. 6: 334. 1S01-2. 



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

 with f^pposite or alternate, mostly finely dissected leaves, and small peduncled heads of both 

 tub> -ar and radiate yellow flowers. Involucre cylindric, campanulatc or nearly hemispheric, 

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

 ceptacle flat, pubescent, or covered with short bristles. Ray-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, 3-5angled, striate. Pappus of about 10 scales, parted 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. 



I. Dysodia papposa (Vent.) A. S. Hitchcock. Fetid Marigold. False 

 Dog-fennel. (Fig. 3979.) 



Tageles papposa Veut. Hort. Cels, pi. j6. 1800. 

 Boebera clirysanlhemoides Willd. Sp. PI. 3: 2125. 1S04. 

 Dysodia chrysanlhemoides Lag Gen. et Sp. Nov. 29. 1816. 

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



.\nnual, very leafy, glabrous or finely pubescent, 

 gland-dotted, much branched, 6'-i.S' high, the branches 

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

 oled, y^'-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 S-io 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, Me.xico 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. 18 16. 

 [Hy.mi:n.\theru.m Cass. Bull. Soc. Philom. 1817: 12. iSry.] 



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- 

 em parts of the United States. 



I. Thymophylla aurea (A. Gray) 

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



Lozvellia aurea A. Grav, Mem. Am. Acad. (11)4:91. 



1849. 

 Hymenatherum aureum A. Graj-, 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, (^"-\o" broad, terminating 

 the branches; involucre about 3" high, its bracts 

 acute; rays about 12, 2^"-3" long; pappus of 6-8 

 erose truncate scales, somewhat longer than the 

 thickness of the acbene. 



Kansas and Colorado to Texas. June-Sept. 



