AMBROSIACEAE | 1301 
racemes, the staminate with saucer-shaped 
or turbinate lobed involueres. Pistillate in- 
voluere of several fused bracts, nut-like, be- 
coming a several. or many-spined - 2- 
lipped or 2-beaked at the tip.—About 25 
species, American.—RAGWEEDS 
F. confertiflora (DC.) Rydb.  Peren- 
nial, 2 m. tall or less, more or less strigose: 
acute, the terminal o longate: stami- 
nate inv e 2 mm. h nearl 0, 
hirsutulous: fruit ovoid or globose in outline, 
2-3 i, eak and 
usually 6-18 spines.—Plains and moist pounds various provinces, Tenn. to 
Tex., N. M., and Colo.—(Mez.)—Sum.-f 
4. ACANTHOXANTHIUM Fourr.1 . Coarse monoecious annuit herbs. 
Leaves alternate, with 3-pronged or simple stipular spines: blades pinnately 
lobed or entire. Staminate heads mostly in 
terminal capitate clusters: involuere of dis- 
tinct bracts: corolla tubular-funnelfo 
lobed: filaments ee Pistillate 
involucres axillary, closed, or 2-beaked 
or sometimes beakless, the "" y cylindric- 
ellipsoid, 1- or 2-flowered, armed with nu- 
merous spines which are first bent eid 
bur.—Four species, South American. | 
. A. spinosum (L.) Fourr. Stem 3-10 dm. 
tall, in age stramineous, branched: deg blades lanceolate, entire rs 3—5-lobed, 
p ia above, white- Vu beneath, 5-10 em. a spines 3-pronged, up 
to ong: bur with m ellipsoid Pa 10- 13 mm. long, pubescent, the 
Lies about 2 mm. long; the beaks up to 3 mm. lon P [ Xanthium a 
L. ]—(CLoTBUR. E io fields, and roadsides, 20 us provi Fla. 
to Tex., Calif., B. C., and Me. Nat. of S. Am.—(W. I., Mes., C. A. 0 W.) 
— Sum l 
9. XANTHIUM I.1 Coarse monoecious annual herbs. Leaves alter- 
nate: blades usually ovate to reniform in outline, more or less digitately 3-5- 
Icbed, often cordate at the base. Staminate heads in terminal spikes or racemes: 
involucre of distinct bracts in 1-3 series: corolla 1 ee 5-lobed 
laments monadelphous. Pistillate involucre closed, or 3-beaked, the WES 
P fusiform, ellipsoid, or ovoid, 2- or 3-flowered, ped oi M which 
re hooked at the apex, the beaks nearly equal, m r less curved, 2-lobed, 
a: outer lobe the longer and incurved: corolla onde stigmas 2. Achene 
3 Contributed by the late Per Axel Rydberg. 
