344 DESCRIPTIONS OF NEW SPECIES 



long and slender. Scales or sepals yellowish-white, rigid and cartilaginous, strongly ciliate, those 

 which embrace the achenium subcarinate, and splitting at length in the centre down to the base ; 

 points of the scales abruptly terminating in narrow, bracteolate, leafy, hirsute, spreading points. 

 Rays eight, about twice the length of the disk, mostly entire, the tube short and narrow. Stigmas 

 of the ray long, ligulate, smooth, bifid. Achenium blackish, convex and strongly carinated on the 

 back, oboval, scabrous and hairy towards the summit, without any vestige of winged margin, 

 crowned by a minute cup, terminated on either side by two very small and hairy awns. Ache- 

 nium falling off with the scale to which it is attached, and to each of which adheres two recepta- 

 cular palea, with the stalk like rudiments of the male flowers. 



Division V. — Ambrosie^. (Decand.) 

 Ambrosia hidentata. 



Hab. Arkansa plains. The uppermost leaves frequently four-toothed on either side, near the 

 base; male involucrum entire, six to eight flowered, with a projecting caudate segment. 



Ambrosia trijida. 



Hab. Arkansa; in inundated places. 



Ambrosia * longistylis; scabrous, stem (apparently) simple ; leaves pinnatifid, 

 segments oblong-linear, bractes entire; female flowers axillary, conglomerate, 

 with exceedingly long styles, (about an inch.;) fruit cornute, spiny at the sum- 

 mit; male flowers about thirty, in a slightly toothed involucrum; the recepta- 

 cle filiformly paleaceous; cusps of the anthers filiform. 



Hab. Rocky Mountains. ©. Allied to Franseria. 



FRANSERIA. (Cavan.) 



Franseria ^bipinnatijida; %, herbaceous, decumbent and diffusely branched, 

 canescent and sericeous; leaves bipinnatifid, ultimate segments linear, short, 

 obtuse and confluent; male calyx ten to twelve-cleft, many-flowered. — F. Cha-- 

 missonis, (3. bipinnatisecta? Lessing, Decand., Vol. V., p. 524.. 



Hab. Sea-coast of Upper California, (St. Barbara, St. Diego, &c.,) common. Stem diffuse, 

 spreading in a circle of two or three feet, solid, but not woody, brownish. Male florets about 

 thirty; fruit in clusters or racemes, very spiny and pungent, the involucrum pyramidal-ovate; 

 spines flat, often brown, or yellowish. Stigmas filiform, rather long and acute. Anthers, (in the 

 manner of the genus,) with filiformly acute tips. 



Franseria ^pumila; %, sericeously canescent, root creeping; stem erect; very 

 low and short; leaves tripinnatifid, ultimate segments short, linear-oblong, con- 

 fluent; male calyx about five-cleft; spines of the fruit not exserted. 



