CARDUACEAE 1163 
lanceolate, 1-2.5 em. long, coarsely toothed, sessile and partly clasping: involucres 2.5-3 
mm. broad; bracts slightly broadened upward, acute: disk pink or rose-purple: pappus 
more or less concreted. 
On low prairies, southern Texas and adjacent Mexico. 
7. AGERATUM L. 
Perennial caulescent herbs, or shrubby plants. Leaves opposite, or alternate above: 
blades simple, usually toothed. Heads small, discoid, usually in corymbs, white, purple 
or blue. Involucres campanulate : bracts nearly equal, in 2-3 series. Receptacle flat or 
nearly so, naked, or with few caducous scales. Corollas regular, barely distinguishable into 
tube and limb. Stigmas elongated, obtuse. Achenes 5-angled. Pappus simple, of 5 or 
10-20, distinct or partially united scales. The plants bloom from spring to fall. 
Foliage pubescent: pappus of distinct scales. 1. A. conyzoides. 
Foliage glabrous: pappus cup-like or crown-like. 2. A. littorale. 
1. Ageratum conyzoides L. Foliage hirsute. Stems 3-9 dm. tall, often branched : 
leaf-blades ovate to deltoid, 2-5 cm. long, serrate to crenate-serrate, truncate or subcordate 
or rarely broadly cuneate at the base ; petioles shorter than the blades: involucres minutel 
pubescent, or glabrate in age; bracts linear-lanceolate, 2.5-3 mm. long, firm, :ibbed, 
acuminate, serrulate: corollas blue or white: achenes columnar, 1.5 mm. long, each sur- 
mounted by 5-7 rigid distinct pappus-scales. 
In waste places, North Carolina to Florida. 
2. Ageratum littoràle A. Gray. Foliage glabrous. Stems 3-7 dm. long, decumbent 
or assurgent, often diffusely branched : leaf-blades ovate, 1-5 cm. long, crenate-serrate, 
rather fleshy, broadly cuneate at the base; petioles as long as the blades or longer: invo- 
lucres glabrous; bracts linear-lanceolate, 2-2.5 mm. long, acuminate, ribbed: corollas 
blue: achenes about 2 mm. long, each surmounted by a narrow cup-like, rarely toothed 
pappus. 
In sand, Florida Keys. 
8. STEVIA Cav. 
Herbs or shrubby plants, with rigidly or rarely diffusely branched stems. Leaves 
opposite, or the upper alternate: blades usually serrate, and 3-nerved, rarely entire or 3- 
cleft. Heads 5-flowered, loosely or densely clustered. Involucres cylindric: bracts 5-6, 
narrow, rigid, nearly equal. Receptacle naked. Corollas all alike, regular. Anthers ap- 
pendaged, obtuse at the base. Stigmas slender, rather obtuse. Achenes slender some- 
times flattened. Pappus of scales or awns, sometimes both forms together. 
1. Stevia folidsa Small. A branching shrub several dm. tall, with glabrous foliage. 
Leaves numerous, small ones clustered in the axils of the larger; blades narrowly linear 
to almost linear-filiform, 3-10 cm. long, acute, remotely serrate or nearly entire: heads 
few in each cyme : involucres narrowly cylindric, 7-8 mm. high, short-peduncled ; bracts 
linear, acute, ribbed, appressed. ? 
On plains or prairies, southern Texas and Mexico. Spring to fall. 
9. ÓSMIA Sch. Bip. 
Perennial caulescent herbs, or shrubby plants. Leaves opposite : blades broadest 
below the middle, petioled. Heads in corymbose cymules. Involucres ovoid to cylindric : 
bracts numerous, leathery or parchment-like, in several series, with more or less spreading 
colored somewhat foliaceous tips, or herbaceous, conspicuously ribbed, obtuse. Recep- 
tacle flat or slightly convex, naked. Corolla regular. Achenes 5-angled, narrow. Pappus 
of numerous hair-like bristles. 
Tips of the involucral bracts not appressed, decidedly colored, much thinner than the bodies. 
1. O. ivaefolia. 
Tips of the involucral bracts appressed, more or less colored, the inner ones pale, 
each with a very minute colored tip. ; 
Bracts of the involucre 5-7-ribbed : receptacle convex. 2. O. heteroclina, 
Bracts of the involucre 3-ribbed : receptacle flat. 3. O. conyzoides. 
1. Osmia ivaefdlia (L.) Small. Finely pubescent or somewhat hirsute. Stems 
erect, 5-15 dm. tall, finally much branched : leaf-blades lanceolate to oblong-lanceolate or 
linear, acute, usually serrate above the base: involucres oblong-campanulate, 3-5 mm. 
high, 10-2u-flowered ; bracts oblong to linear-oblong, rounded or nearly truncate, some- 
