1 1 I COMPOSITAEJ. 



Btipitate glands and tipped with a truncate gland. Heads solitary or com- 

 monly glomerate at the ends of the branches. Bracts of the convex receptacle 

 each Bubtending a flower, the outer and those of the involucre abundantly 

 covered with slender or clavate colorless gland-tipped processes. Ray-flowers 

 many, willi short yellow Ligules; aehenes 4-ridged on back, the ventral angle 

 ending in a beak. Disk-flowers with sterile aehenes. Pappus none. (Greek 

 holos. whole, and kaiphos, chaff, the whole receptacle HialVy. ) 



1. H. macradenia (DC.) Greene. Branching from above the base, about 1 

 ft. high; herbage unpleasantly odorous; lower leaves linear-oblong, herniate; 



heads \- 2 in. broad. 



Low dry fields about San Francisco Bay. At one time abundant in the 

 fields of South Berkeley. Aug. -Sept. Connects Hemizonia with Centromadia 

 too intimately. 



49. CENTROMADIA Greene. Spikeweed. 



Rigidly branching annuals with alternate spinescent leaves and involucral 

 bracts, the lower pinnatifid, the upper entire. Herbage more or less glandular 

 and scented. Flowers yellow, with 25 to 40 small bifid rays. Receptacle with 

 chaffy bracts throughout, none of the outer united or connate. Disk-achenes 

 chiefly sterile, with or without narrowly linear or bristle-like paleae. Ray- 

 achenes more or less triangular, smooth or roughish on the back, the inner 

 terminated by an erect beak-like apiculation. (Greek kentron, a prickle, and 

 Madia, an allied genus.) 



Herbage yellowish green, sparsely hirsute, sweet- or honey-scented; floral leaves little or 

 not all surpassing the heads 1. C. pungcns. 



Herbage dark, rather densely villous-hirsute, ill-scented; floral leaves often conspicuously 

 surpassing the heads. 2. C. iitchii. 



1. C. pungens (H. & A.) Greene. Common Spikeweed. . Herbage sparsely 

 hirsute or hispid with spreading hairs, hardly viscid or glandular; stems rigidly 

 and freely branching, commonly from near the base, sometimes only above, 1 

 to 2 or 3 feet high; leaves (especially of the flowering branches) linear- 

 subulate, spinose, entire, the lower and lowest pinnately parted into oblong 

 lobes, or pinnatifid, the lobes or teeth spinosely or pungently tipped; bracts 

 of the receptacle cuspidate; pappus of disk none; ray-achenes roughish, some- 

 what laterally 2-nerved on back. — (Hemizonia pungens T. & G.) 



Abundant on the plains of the lower San Joaquin, southward to Southern 

 California and westward to Walnut Creek and Alameda. On the alkaline plains 

 of the upper San Joaquin this species covers tens of thousands of acres and 

 often forms thickets 4 or 5 ft. high. It is a valued bee plant. Var. parrvi 

 Jepson. Minutely glandular; bracts of receptacle thin, not pungent; disk- 

 achenes with 3 to 5 slender almost bristle-like paleae as long as the corolla; 

 ray-achenes semi-obcordate in outline. — Calistoga; Vacaville (=C. rudis Greene, 

 the aehenes either smooth or rough warty) ; Southern California. It is abun- 

 < I .- 1 nt in low more or less alkaline lands on the plains of Solano Co. and forms 

 extensive colonics in summer fields; extermination is often accomplished by 

 means of bands of sheep which leave the fields perfectly clean and destitute of 

 1 his Spikeweed pest. 



2. C. fitchii (Gray) Greene. Fitch's Spikeweed. Diffusely branched from 

 above or at the base, 9 to 16 in. high, the herbage hirsute or villous with 

 spreading hairs; leaves of the radical tuft pinnately parted into remote nar- 

 rowly lineal- pungent lol.es; cnuline leaves linear and entire, tapering into ;i 



subulate or pungenl tip. those ahoul the bead spreading and star-like, mostly all 

 bearing Btipitate glands; bracts of the involucre subulate, those of the recep- 





