CQMPOSITAB (composite, FAMILY) 541 



tendiag the fertile' flowers, or. these wanting in istaminate heads. Receptacular 

 bracts few, narrow. , Pistillate flowers :1 or 2, destitute of corolla; staminate 

 flowers 6-12, the filaments almost free from -the corolla: and monadelphous 

 up to the lightly connected anthers. Achenes surpassing the. outer involucre, 

 copvex on, the (Jorsal side, flat on the anterior face, conspicuously margined 

 with a scariOus pectinate border. Pappus of several small squamellae. 



1. Bicoria Brandegei Gray,.Proc. Am; Acad. 11: 76. 1875. Strigillose- 

 canescent, diffusely and alternately branched: leaves of the branches oblong- 

 lanqeolate or, partly ;spatulate, obtjjse, mostly entire, 3-3 cm. long, and with 

 slender petiple: heads sparse, racemose-paniculate: fertile flower solitary; the 

 dil3,te4-cuneate hyaline subtending bract, hardly surpassing the outer invo- 

 lucre: achiene na£;ed, and exserted, bordered with pectinate callous teeth 

 connected by an indistinct scarioup margiij. — Sandy bottoms of the San Juan, 

 ColoFsidOv 



: 42. AMBROSIA L. Ragweed 



,,. ■,!■, ,. , ,,, ■ ,1 ■;■ . \ . .. .. .. \- : 



Cparse .herbs, with mostly lobed or dissected opposite and,, alterna,te leaves 

 and dull inconspicuous flpwers.- , i$terile heads racemose or spipate and with ho 

 bracts;, fertile flojsirers, usually glonierate in axils below. Involucre of the 

 staminate, flowers depijessed-hemisphericaj to turbinate, 5-1 2-lobed or trun- 

 cate, herbaceous, Receptacle flat or flattish, usually with some filiform chaff 

 amping the outer flowers. Involucre of the splitary fertile flower nutlike, apicu- 

 late or beaked at the;,fipex, and usually arme/1 with 4-8 tjiiberclep ,or short ' 

 spinea in a single} series, below the beak. ., , , ' i 



Leaves entire or palmately 3-cleft: ' involucre of staminate heads ' 

 , ■ 3-4-ribbed . '. : ... . . . . 1. A. trifida. 



Leares once to thrice pinnatifid; involucres of staminate flowers not < , , , 



.i-,li^i|^ed. .I , ■ . . . ,,,, ,. 



Annual; fruit with acute teeth . .... . . . 2. A. artemisiaefdiia. 



Perennial from rootstocks; fruit unarmed or with blunt teeth . 3.' A. psildstachya. 



I 1. Ambrosia trifida L. gp. PI. 987. 1753. Tall and stout, 1-3 m. high,, 

 ronghish-hispid or, ahnost glabrous :;lea'v,es all.opposite, very deeply 3-lobeior 

 the.lower 5-lobed,; the lobes, acuminate, serrate; sterile racemes long. an4 dense; 

 fertile heads clusteredand as if involubrate by short bracts: fruit very thick, 

 with 5-7 strong ribs or angles terminating above in spinous tubercles around 

 the base of the conical beak. Var. integrifolia T- & G- with entire leaves. 

 Great Ragweed.- — Moi^t banks an,d draws; Colorado and f^r northward and 

 eastward. .■„-,,,■,!,: , , ,,. 1 1,,,, ,, , , , , 



2. Ambrosia artemisiaefolia L. 1. c. Variously pubescent pr. hirsute, panic- 

 ulately branched, 3-6; |dm. high, or taller: leaves thinni^, bipinnatifid, or 

 pinujately parted, with the divisions irregularly pinnatifid or sometimes nearly 

 entire, on the flowering branches oftew undivided: sterile heads pediceled: 

 fruit short-beaked, arinediwith 4-6 short acute teeth or spines,— A weed in 

 waste and cultiva/ted grounds across the continent, knoyvn variously as 

 Roman Wormwood, Ragweed^, and BiTTERWBED. . ,,,,! .hi' 



3. Ambrosia psilostachya DC. Prodr. 5: 526. 1836. Stems simple, erect, 

 commonly 5-10 (2-15) dm^ high framj-,Blender running rootstocks; herbage 

 scabro^s or short-hirsute, spmewhaf; strigose:. leaves once or the lower twice 

 pinnatifid, with acute lobes: 'fruit an obovoid turgid bur, about 3 mm. long, 

 nibstly solitary in the axilsj pubescent, rugose-reticulated, bearing 4 pro- 

 tubeiiailces or Sometimes unaniied. Western Ragweed. — A'common weed 

 along roadsides and in waste places throughout westiern North America. 



,. / „i 43j FRANSERIACay, 



burs are herbaceous, witli chiefly alternate leaves, and the spines of the 

 fruiting and 1-2-flowered involucre comparatively few. Heads of staminate 

 flowersias in Ambrosia, or sometimes intermixed with the pistillate. Fertile 

 invoitiore l-4-flowered.,l-4-celled,ai single pistil to each cell, 1^-rostrate, 



